Enhanced Flight Vision System

- James Albright (a former G450 driver)

Update: 2018-06-01

Prior to December 13, 2016, the regulations for EFVS operations to 100 feet above the touchdown zone elevation (TDZE) were located in § 91.175(l) and (m). The EFVS final rule published on December 13, 2016 revised these regulations and moved them to § 91.176(b). The transition period for operators to comply with the new requirements of § 91.176(b) ended on March 13, 2018. Operators who conduct EFVS operations to 100 feet above the TDZE must comply with § 91.176(b) and the requirements of § 61.66. Do you need OpSpec or LOA approval? It depends. Are you operating commercially and using EVS from touchdown to rollout? Then yes. Are you operating internationally down to 100 feet above the TDZE? Then maybe. It is complicated . . .

Our experience with the G450 EVS has been a mixed bag. There have been a few times where we magically spotted the runway with EFVS hundreds of feet earlier and all was good. More times than not, however, the system was no better than the pilot's natural vision. A few times, the system just wouldn't come up. After three years of this we came to the conclusion it is nice to have, especially for keeping clear of en route weather, but you cannot count on it. It has been nine years now and we haven't changed our opinion on this. For information about the HUD itself, refer to G450 Heads Up Display.

Much of this is pretty tedious government-speak but there are things you need to know. I've tried to highlight the important bits.

Everything here is from the references shown below, with a few comments in an alternate color.

Figure: Phases of an EFVS Approach, from Eddie's notes.

Basic Concept

[AC 90-106A ¶2.2] Definition of an EFVS. Imaging-sensor technologies can offer significant advantages in both safety and capability for low-visibility flight operations. Section 1.1 defines an EFVS as “…an installed aircraft system which uses an electronic means to provide a display of the forward external scene topography (the natural or manmade features of a place or region especially in a way to show their relative positions and elevation) through the use of imaging sensors, including but not limited to forward-looking infrared, millimeter wave radiometry, millimeter wave radar, or low-light level image intensification. An EFVS includes the display element, sensors, computers and power supplies, indications, and controls.”

[AC 90-106A, ¶2.3.1] An EFVS uses a transparent HUD or equivalent display to combine flight information, flight symbology, navigation guidance, and a real-time image of the external scene to the pilot on one display. Imaging sensors, which may be based on FLIR, millimeter wave radiometry, millimeter wave radar, low-level light intensification, or other real-time imaging technologies, produce a real-time image of the outside scene. Depending on atmospheric conditions and the strength of energy emitted and/or reflected from the outside scene, an EFVS can enable a pilot to see the approach lights, visual references associated with the runway environment, and other objects or features that might not be visible using natural vision alone.

[AC 90-106A, ¶2.3.2] The overall purpose of an EFVS is to enable a pilot to use enhanced vision imagery in lieu of natural vision to descend below DA/DH or MDA. Use of an EFVS may improve safety by enhancing situation and position awareness, providing visual cues to maintain a stabilized approach, and minimizing missed approaches. Even in situations where the flight visibility under § 91.175(c)(2) is sufficient for a pilot to use natural vision to descend below DA/DH or MDA, an EFVS may provide useful visual cues for enhanced situation awareness.

EFVS vs EVS?

[AC 90-106A, ¶1.4.4] An EVS is an electronic means to provide the flightcrew with a sensor-derived or enhanced image of the external scene using millimeter wave radar, Forward Looking Infrared (FLIR), or other sensor technologies to provide a real-time image of the external scene. An EVS may present a sensor image on a head-down display (HDD), but it may not be able to present the sensor image and flight symbology in the same scale and alignment as the outside view. It is important to note that an EVS can also use a Head-Up Display (HUD) as its display element, yet still not meet the regulatory requirements for an EFVS. While an EVS that uses an HDD or HUD may provide situation awareness to the pilot, it does not meet the operating requirements for EFVS under § 91.176; § 91.1039; part 121, § 121.651; part 125, § 125.381; or part 135, § 135.225. Consequently, a pilot cannot use an EVS in lieu of natural vision to descend below DA/DH or MDA.

What's in a name? Why does it matter? Gulfstream was leading the pack on this and decided to call the Forward Looking Infrared (FLIR) to Heads Up Display (HUD) interface an Enhanced Vision System (EVS). The FAA, years later, decided an EVS was the heads down portion and decided to call the heads up portion Enhanced Flight Vision System (EFVS). The Gulfstream system is certified to take advantage of 14 CFR 91.175, so where the regulation says EFVS, in the Gulfstream fleet that means EVS.

Two Types of EFVS Operations:

[AC 90-106A, ¶2.5.1.1] EFVS Operations to Touchdown and Rollout. An EFVS operation to touchdown and rollout is an operation in which the pilot uses the enhanced vision imagery provided by an EFVS in lieu of natural vision to descend below DA or DH to touchdown and rollout.

[AC 90-106A, ¶2.5.1.2] EFVS Operations to 100 feet Above the TDZE.

An EFVS operation to 100 feet above the TDZE is an operation in which the pilot uses the enhanced vision imagery provided by an EFVS in lieu of natural vision to descend below DA/DH or MDA down to 100 feet above the TDZE.
Natural vision must be used to descend below 100 feet above the TDZE. These operations may be conducted on IAPs that have a DA/DH or MDA. You can find the regulations for EFVS operations to 100 feet above the TDZE in § 91.176(b).

The advisory circular places "touchdown and rollout" before "to 100 feet above the TDZE" throughout. I found this confusing (you have to do the latter to get to the former) so I've reordered them. In general, remember the requirements to use EFVS are stricter going from touchdown to rollout, as are the requirements to obtain approval.

Regulatory

The U.S. regulation (14 CFR 91.176) can be confusing until you realize it is talking about two separate things. The first part covers using EFVS from touchdown and rollout, which requires an LOA, OpSpec, or MSpec authorization. The second part covers using EFVS to 100 feet above TDZE, which does not require an authorization if you are operating under Part 91 (other than subpart K). When operating internationally, however, things can change and an LOA may be required.

U.S., ICAO, and EASA rules specify similar requirements for the approach, visibility requirements, and other rules.

If you arrive at the MDA or DA/DH and have the necessary "enhanced flight visibility" (you can see the required visual references using EFVS), you can continue down to 100 feet above TDZE. At that point, you must have the necessary "flight visibility" (you can see the required visual references without the EFVS).

United States

[14 CFR 91.176] Straight-in landing operations below DA/DH or MDA using an enhanced flight vision system (EFVS) under IFR.

To touchdown and rollout:

(a) EFVS operations to touchdown and rollout. Unless otherwise authorized by the Administrator to use an MDA as a DA/DH with vertical navigation on an instrument approach procedure, or unless paragraph (d) of this section applies, no person may conduct an EFVS operation in an aircraft, except a military aircraft of the United States, at any airport below the authorized DA/DH to touchdown and rollout unless the minimums used for the particular approach procedure being flown include a DA or DH, and the following requirements are met:

(1) Equipment.

(i) The aircraft must be equipped with an operable EFVS that meets the applicable airworthiness requirements. The EFVS must:

(A) Have an electronic means to provide a display of the forward external scene topography (the applicable natural or manmade features of a place or region especially in a way to show their relative positions and elevation) through the use of imaging sensors, including but not limited to forward-looking infrared, millimeter wave radiometry, millimeter wave radar, or low-light level image intensification.

(B) Present EFVS sensor imagery, aircraft flight information, and flight symbology on a head up display, or an equivalent display, so that the imagery, information and symbology are clearly visible to the pilot flying in his or her normal position with the line of vision looking forward along the flight path. Aircraft flight information and flight symbology must consist of at least airspeed, vertical speed, aircraft attitude, heading, altitude, height above ground level such as that provided by a radio altimeter or other device capable of providing equivalent performance, command guidance as appropriate for the approach to be flown, path deviation indications, flight path vector, and flight path angle reference cue. Additionally, for aircraft other than rotorcraft, the EFVS must display flare prompt or flare guidance.

(C) Present the displayed EFVS sensor imagery, attitude symbology, flight path vector, and flight path angle reference cue, and other cues, which are referenced to the EFVS sensor imagery and external scene topography, so that they are aligned with, and scaled to, the external view.

(D) Display the flight path angle reference cue with a pitch scale. The flight path angle reference cue must be selectable by the pilot to the desired descent angle for the approach and be sufficient to monitor the vertical flight path of the aircraft.

(E) Display the EFVS sensor imagery, aircraft flight information, and flight symbology such that they do not adversely obscure the pilot's outside view or field of view through the cockpit window.

(F) Have display characteristics, dynamics, and cues that are suitable for manual control of the aircraft to touchdown in the touchdown zone of the runway of intended landing and during rollout.

(ii) When a minimum flightcrew of more than one pilot is required, the aircraft must be equipped with a display that provides the pilot monitoring with EFVS sensor imagery. Any symbology displayed may not adversely obscure the sensor imagery of the runway environment.

(2) Operations.

(i) The pilot conducting the EFVS operation may not use circling minimums.

(ii) Each required pilot flightcrew member must have adequate knowledge of, and familiarity with, the aircraft, the EFVS, and the procedures to be used.

(iii) The aircraft must be equipped with, and the pilot flying must use, an operable EFVS that meets the equipment requirements of paragraph (a)(1) of this section.

(iv) When a minimum flightcrew of more than one pilot is required, the pilot monitoring must use the display specified in paragraph (a)(1)(ii) to monitor and assess the safe conduct of the approach, landing, and rollout.

(v) The aircraft must continuously be in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers.

(vi) The descent rate must allow touchdown to occur within the touchdown zone of the runway of intended landing.

(vii) Each required pilot flightcrew member must meet the following requirements—

(A) A person exercising the privileges of a pilot certificate issued under this chapter, any person serving as a required pilot flightcrew member of a U.S.-registered aircraft, or any person serving as a required pilot flightcrew member for a part 121, 125, or 135 operator, must be qualified in accordance with part 61 and, as applicable, the training, testing, and qualification provisions of subpart K of this part, part 121, 125, or 135 of this chapter that apply to the operation; or

(B) Each person acting as a required pilot flightcrew member for a foreign air carrier subject to part 129, or any person serving as a required pilot flightcrew member of a foreign registered aircraft, must be qualified in accordance with the training requirements of the civil aviation authority of the State of the operator for the EFVS operation to be conducted.

(viii) A person conducting operations under this part must conduct the operation in accordance with a letter of authorization for the use of EFVS unless the operation is conducted in an aircraft that has been issued an experimental certificate under §21.191 of this chapter for the purpose of research and development or showing compliance with regulations, or the operation is being conducted by a person otherwise authorized to conduct EFVS operations under paragraphs (a)(2)(ix) through (xii) of this section. A person applying to the FAA for a letter of authorization must submit an application in a form and manner prescribed by the Administrator.

(ix) A person conducting operations under subpart K of this part must conduct the operation in accordance with management specifications authorizing the use of EFVS.

(x) A person conducting operations under part 121, 129, or 135 of this chapter must conduct the operation in accordance with operations specifications authorizing the use of EFVS.

(xi) A person conducting operations under part 125 of this chapter must conduct the operation in accordance with operations specifications authorizing the use of EFVS or, for a holder of a part 125 letter of deviation authority, a letter of authorization for the use of EFVS.

(xii) A person conducting an EFVS operation during an authorized Category II or Category III operation must conduct the operation in accordance with operations specifications, management specifications, or a letter of authorization authorizing EFVS operations during authorized Category II or Category III operations.

In other words, if you want to use your EVFS to operate from touchdown to rollout, you are going to need an OpSpec or an LOA.

(3) Visibility and visual reference requirements. No pilot operating under this section or §§121.651, 125.381, or 135.225 of this chapter may continue an approach below the authorized DA/DH and land unless:

(i) The pilot determines that the enhanced flight visibility observed by use of an EFVS is not less than the visibility prescribed in the instrument approach procedure being used.

(ii) From the authorized DA/DH to 100 feet above the touchdown zone elevation of the runway of intended landing, any approach light system or both the runway threshold and the touchdown zone are distinctly visible and identifiable to the pilot using an EFVS.

(A) The pilot must identify the runway threshold using at least one of the following visual references—

(1) The beginning of the runway landing surface;

(2) The threshold lights; or

(3) The runway end identifier lights.

(B) The pilot must identify the touchdown zone using at least one of the following visual references—

(1) The runway touchdown zone landing surface;

(2) The touchdown zone lights;

(3) The touchdown zone markings; or

(4) The runway lights.

(iii) At 100 feet above the touchdown zone elevation of the runway of intended landing and below that altitude, the enhanced flight visibility using EFVS must be sufficient for one of the following visual references to be distinctly visible and identifiable to the pilot—

(A) The runway threshold;

(B) The lights or markings of the threshold;

(D) The lights or markings of the touchdown zone.

(4) Additional requirements. The Administrator may prescribe additional equipment, operational, and visibility and visual reference requirements to account for specific equipment characteristics, operational procedures, or approach characteristics. These requirements will be specified in an operator's operations specifications, management specifications, or letter of authorization authorizing the use of EFVS.

These requirements are similar to those for operating to 100 feet above the TDZE, which follow.

To 100 feet above TDZE:

(b) EFVS operations to 100 feet above the touchdown zone elevation. Except as specified in paragraph (d) of this section, no person may conduct an EFVS operation in an aircraft, except a military aircraft of the United States, at any airport below the authorized DA/DH or MDA to 100 feet above the touchdown zone elevation unless the following requirements are met:

(1) Equipment. (i) The aircraft must be equipped with an operable EFVS that meets the applicable airworthiness requirements.

(ii) The EFVS must meet the requirements of paragraph (a)(1)(i)(A) through (F) of this section, but need not present flare prompt, flare guidance, or height above ground level.

(2) Operations. (i) The pilot conducting the EFVS operation may not use circling minimums.

(ii) Each required pilot flightcrew member must have adequate knowledge of, and familiarity with, the aircraft, the EFVS, and the procedures to be used.

(iii) The aircraft must be equipped with, and the pilot flying must use, an operable EFVS that meets the equipment requirements of paragraph (b)(1) of this section.

(iv) The aircraft must continuously be in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers.

(v) For operations conducted under part 121 or part 135 of this chapter, the descent rate must allow touchdown to occur within the touchdown zone of the runway of intended landing.

(vi) Each required pilot flightcrew member must meet the following requirements—

(vii) A person conducting operations under subpart K of this part must conduct the operation in accordance with management specifications authorizing the use of EFVS.

(viii) A person conducting operations under part 121, 129, or 135 of this chapter must conduct the operation in accordance with operations specifications authorizing the use of EFVS.

(ix) A person conducting operations under part 125 of this chapter must conduct the operation in accordance with operations specifications authorizing the use of EFVS or, for a holder of a part 125 letter of deviation authority, a letter of authorization for the use of EFVS.

(x) A person conducting an EFVS operation during an authorized Category II or Category III operation must conduct the operation in accordance with operations specifications, management specifications, or a letter of authorization authorizing EFVS operations during authorized Category II or Category III operations.

(3) Visibility and Visual Reference Requirements. No pilot operating under this section or §121.651, §125.381, or §135.225 of this chapter may continue an approach below the authorized MDA or continue an approach below the authorized DA/DH and land unless:

(i) The pilot determines that the enhanced flight visibility observed by use of an EFVS is not less than the visibility prescribed in the instrument approach procedure being used.

(ii) From the authorized MDA or DA/DH to 100 feet above the touchdown zone elevation of the runway of intended landing, any approach light system or both the runway threshold and the touchdown zone are distinctly visible and identifiable to the pilot using an EFVS.

(A) The pilot must identify the runway threshold using at least one of the following visual references-

(1) The beginning of the runway landing surface;

(2) The threshold lights; or

(3) The runway end identifier lights.

(B) The pilot must identify the touchdown zone using at least one of the following visual references—

(1) The runway touchdown zone landing surface;

(2) The touchdown zone lights;

(3) The touchdown zone markings; or

(4) The runway lights.

(iii) At 100 feet above the touchdown zone elevation of the runway of intended landing and below that altitude, the flight visibility must be sufficient for one of the following visual references to be distinctly visible and identifiable to the pilot without reliance on the EFVS—

(A) The runway threshold;

(B) The lights or markings of the threshold;

(D) The lights or markings of the touchdown zone.

(4) Compliance Date. Beginning on March 13, 2018, a person conducting an EFVS operation to 100 feet above the touchdown zone elevation must comply with the requirements of paragraph (b) of this section.

(c) Public aircraft certification and training requirements. A public aircraft operator, other than the U.S. military, may conduct an EFVS operation under paragraph (a) or (b) of this section only if:

(1) The aircraft meets all of the civil certification and airworthiness requirements of paragraph (a)(1) or (b)(1) of this section, as applicable to the EFVS operation to be conducted; and

(2) The pilot flightcrew member, or any other person who manipulates the controls of an aircraft during an EFVS operation, meets the training, recent flight experience and refresher training requirements of §61.66 of this chapter applicable to EFVS operations.

(d) Exception for Experimental Aircraft. The requirement to use an EFVS that meets the applicable airworthiness requirements specified in paragraphs (a)(1)(i), (a)(2)(iii), (b)(1)(i), and (b)(2)(iii) of this section does not apply to operations conducted in an aircraft issued an experimental certificate under §21.191 of this chapter for the purpose of research and development or showing compliance with regulations, provided the Administrator has determined that the operations can be conducted safely in accordance with operating limitations issued for that purpose.

ICAO

[AC 90-106A, ¶4.3.8]

Currently, most foreign CAAs require a specific approval to conduct EFVS operations. As a result, a foreign CAA may require a U.S. operator who wishes to conduct EFVS operations in their country to obtain an FAA-issued authorization. Part 91 operators (other than part 91K operators) are not required to obtain an LOA to conduct EFVS operations to 100 feet above the TDZE within the United States. A part 91 operator conducting EFVS operations to 100 feet above the TDZE outside of the United States may request an LOA from the FAA. The FAA strongly recommends that operators contact the CAA of each country in which they plan to conduct EFVS operations to determine the equipment requirements, operational approval requirements, and requirements for conducting EFVS operations, since those requirements may be different from those of the United States. Operators of U.S.-registered civil aircraft that are conducting operations outside of the United States must comply with § 91.703 and other applicable regulations pertaining to operations that are conducted outside the United States.
This is a change in the FAA's position. They had been reluctant to issue the LOA but that is now changed. Your FSDO may drag their feet on this, but it is something they must do if you request it.
ICAO Annex 6, Parts I, II, and III contain information about international operations using EFVS (referred to as EVS in Annex 6). The ICAO Manual of All-Weather Operations (ICAO Doc 9365) contains additional guidance. The AIP issued by a particular State may also contain information about EFVS operations in that country.
Annex 6 is pretty much the basis for the U.S. regulations and follows below. Doc 9365 goes beyond FAA guidance by providing RVR reductions, shown below.
The cited 14 CFR 91.703 simply says you have to play by the applicable rules of whomever owns the airspace.

[14 CFR 91.703] Operations of civil aircraft of U.S. registry outside of the United States.

Each person operating a civil aircraft of U.S. registry outside of the United States shall—
1. When over the high seas, comply with Annex 2 (Rules of the Air) to the Convention on International Civil Aviation and with §§91.117(c), 91.127, 91.129, and 91.131;
2. When within a foreign country, comply with the regulations relating to the flight and maneuver of aircraft there in force;
3. Except for §§91.117(a), 91.307(b), 91.309, 91.323, and 91.711, comply with this part so far as it is not inconsistent with applicable regulations of the foreign country where the aircraft is operated or Annex 2 of the Convention on International Civil Aviation; and
4. When operating within airspace designated as Reduced Vertical Separation Minimum (RVSM) airspace, comply with §91.706.
5. For aircraft subject to ICAO Annex 16, carry on board the aircraft documents that summarize the noise operating characteristics and certifications of the aircraft that demonstrate compliance with this part and part 36 of this chapter.
Annex 2 to the Convention on International Civil Aviation, Rules of the Air, Tenth Edition—July 2005, with Amendments through Amendment 45, applicable November 10, 2016, is incorporated by reference into this section with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51.

[ICAO Annex 6 Part I, ¶6.24] and [ICAO Annex 6 Part II, ¶2.4.15] and [ICAO Annex 6 Part III, ¶4.16]

6.24.1 Where aeroplanes are equipped with automatic landing systems, a HUD or equivalent displays, EVS, SVS or CVS, or any combination of those systems into a hybrid system, the use of such systems for the safe operation of an aeroplane shall be approved by the State of the Operator.

Note.— Information regarding a HUD or equivalent displays, including references to RTCA and EUROCAE documents, is contained in the Manual of All-Weather Operations (Doc 9365).

6.24.2 In approving the operational use of automatic landing systems, a HUD or equivalent displays, EVS, SVS or CVS, the State of the Operator shall ensure that:

a) the equipment meets the appropriate airworthiness certification requirements;

b) the operator has carried out a safety risk assessment of the operations supported by the automatic landing systems, a HUD or equivalent displays, EVS, SVS or CVS;

c) the operator has established and documented the procedures for the use of, and training requirements for, automatic landing systems, a HUD or equivalent displays, EVS, SVS or CVS.

[ICAO Doc 9365, Appendix G]

A pilot using an appropriately certificated enhanced vision system (EVS) in accordance with the procedures and limitations of the approved flight manual may:
1. continue an approach below DH or MDH to 100 ft above the threshold elevation of the runway provided that at least one of the following visual references is displayed and identifiable on the EVS:
  - elements of the approach lighting; or
  - the runway threshold, identified by at least one of the following: the beginning of the runway landing surface, the threshold lights, the threshold identification lights; and the touchdown zone, identified by at least one of the following: the runway touchdown zone landing surface, the touchdown zone lights, the touchdown zone markings or the runway lights.
2. reduce the calculated RVR for the approach from the value in column 1 of Table G-1 to the value in column 2.
Paragraph 1 may, for example be used for ILS, MLS, PAR, GLS and RNAV with approved vertical guidance approach procedures with a DH no lower than 200 ft or an approach flown using approved vertical flight path guidance to an MDH or DH no lower than 250 ft.
A pilot may not continue an approach below 100 ft above runway threshold elevation for the intended runway unless at least one of the visual references specified below is distinctly visible and identifiable to the pilot without reliance on the EVS:
- the lights or markings of the threshold; or
- the lights or markings of the touchdown zone.

Photo: EVS RVR Reduction, ICAO Doc 9365, Table G-1
Click photo for a larger image

European Union

[EASA Air Ops, AMC1 CAT.OP.MPA.305(e), ¶(e)] Approach operations utilising EVS - CAT I operations

(1) At DH, the following visual references should be displayed and identifiable to the pilot on the EVS image:

(i) elements of the approach light; or

(ii) the runway threshold, identified by at least one of the following:

(A) the beginning of the runway landing surface,

(B) the threshold lights, the threshold identification lights; or

(C) the touchdown zone, identified by at least one of the following: the runway touchdown zone landing surface, the touchdown zone lights, the touchdown zone markings or the runway lights.

(2) At 100 ft above runway threshold elevation, at least one of the visual references specified below should be distinctly visible and identifiable to the pilot without reliance on the EVS:

(i) the lights or markings of the threshold; or

(ii) the lights or markings of the touchdown zone.

[EASA Air Ops, AMC1 CAT.OP.MPA.305(e), ¶(e)] Approach operations utilising EVS — APV and NPA operations flown with the CDFA technique

(1) At DH/MDH, visual references should be displayed and identifiable to the pilot on the EVS image as specified under (a).

At 200 ft above runway threshold elevation, at least one of the visual references specified under (a) should be distinctly visible and identifiable to the pilot without reliance on the EVS.

EASA Air Ops, AMC6 SPA.LVO.100 specifies EVS RVR reductions identical to the previously listed ICAO Doc 9365 criteria.

Qualification

You have to be trained, that training has to be document, and you have to have had recent experience.

[14 CFR 61.66] Enhanced Flight Vision System Pilot Requirements.

Ground Training

(a) Ground training. (1) Except as provided under paragraphs (f) and (h) of this section, no person may manipulate the controls of an aircraft or act as pilot in command of an aircraft during an EFVS operation conducted under §91.176(a) or (b) of this chapter, or serve as a required pilot flightcrew member during an EFVS operation conducted under §91.176(a) of this chapter, unless that person—

(i) Receives and logs ground training under a training program approved by the Administrator; and

(ii) Obtains a logbook or training record endorsement from an authorized training provider certifying the person satisfactorily completed the ground training appropriate to the category of aircraft for which the person is seeking the EFVS privilege.

(2) The ground training must include the following subjects:

(i) Those portions of this chapter that relate to EFVS flight operations and limitations, including the Airplane Flight Manual or Rotorcraft Flight Manual limitations;

(ii) EFVS sensor imagery, required aircraft flight information, and flight symbology;

(iii) EFVS display, controls, modes, features, symbology, annunciations, and associated systems and components;

(iv) EFVS sensor performance, sensor limitations, scene interpretation, visual anomalies, and other visual effects;

(v) Preflight planning and operational considerations associated with using EFVS during taxi, takeoff, climb, cruise, descent and landing phases of flight, including the use of EFVS for instrument approaches, operating below DA/DH or MDA, executing missed approaches, landing, rollout, and balked landings;

(vi) Weather associated with low visibility conditions and its effect on EFVS performance;

(vii) Normal, abnormal, emergency, and crew coordination procedures when using EFVS; and

(viii) Interpretation of approach and runway lighting systems and their display characteristics when using an EFVS.

Flight Training

(b) Flight training. (1) Except as provided under paragraph (h) of this section, no person may manipulate the controls of an aircraft or act as pilot in command of an aircraft during an EFVS operation under §91.176(a) or (b) of this chapter unless that person—

(i) Receives and logs flight training for the EFVS operation under a training program approved by the Administrator; and

(ii) Obtains a logbook or training record endorsement from an authorized training provider certifying the person is proficient in the use of EFVS in the category of aircraft in which the training was provided for the EFVS operation to be conducted.

(2) Flight training must include the following tasks:

(i) Preflight and inflight preparation of EFVS equipment for EFVS operations, including EFVS setup and use of display, controls, modes and associated systems, and adjustments for brightness and contrast under day and night conditions;

(ii) Proper piloting techniques associated with using EFVS during taxi, takeoff, climb, cruise, descent, landing, and rollout, including missed approaches and balked landings;

(iii) Proper piloting techniques for the use of EFVS during instrument approaches, to include operations below DA/DH or MDA as applicable to the EFVS operations to be conducted, under both day and night conditions;

(iv) Determining enhanced flight visibility;

(v) Identifying required visual references appropriate to EFVS operations;

(vi) Transitioning from EFVS sensor imagery to natural vision acquisition of required visual references and the runway environment;

(vii) Using EFVS sensor imagery, required aircraft flight information, and flight symbology to touchdown and rollout, if the person receiving training will conduct EFVS operations under §91.176(a) of this chapter; and

(viii) Normal, abnormal, emergency, and crew coordination procedures when using an EFVS.

(c) Supplementary EFVS training. A person qualified to conduct an EFVS operation under §91.176(a) or (b) of this chapter who seeks to conduct an additional EFVS operation for which that person has not received training must—

(1) Receive and log the ground and flight training required by paragraphs (a) and (b) of this section, under a training program approved by the Administrator, appropriate to the additional EFVS operation to be conducted; and

(2) Obtain a logbook or training record endorsement from the authorized training provider certifying the person is proficient in the use of EFVS in the category of aircraft in which the training was provided for the EFVS operation to be conducted.

Currency

(d) Recent flight experience: EFVS. Except as provided in paragraphs (f) and (h) of this section, no person may manipulate the controls of an aircraft during an EFVS operation or act as pilot in command of an aircraft during an EFVS operation unless, within 6 calendar months preceding the month of the flight, that person performs and logs six instrument approaches as the sole manipulator of the controls using an EFVS under any weather conditions in the category of aircraft for which the person seeks the EFVS privilege. The instrument approaches may be performed in day or night conditions; and

(1) One approach must terminate in a full stop landing; and

(2) For persons authorized to exercise the privileges of §91.176(a), the full stop landing must be conducted using the EFVS.

(e) EFVS refresher training. (1) Except as provided in paragraph (h) of this section, a person who has failed to meet the recent flight experience requirements of paragraph (d) of this section for more than six calendar months may reestablish EFVS currency only by satisfactorily completing an approved EFVS refresher course in the category of aircraft for which the person seeks the EFVS privilege. The EFVS refresher course must consist of the subjects and tasks listed in paragraphs (a)(2) and (b)(2) of this section applicable to the EFVS operations to be conducted.

(2) The EFVS refresher course must be conducted by an authorized training provider whose instructor meets the training requirements of this section and, if conducting EFVS operations in an aircraft, the recent flight experience requirements of this section.

(f) Military pilots and former military pilots in the U.S. Armed Forces. (1) The training requirements of paragraphs (a) and (b) of this section applicable to EFVS operations conducted under §91.176(a) of this chapter do not apply to a military pilot or former military pilot in the U.S. Armed Forces if that person documents satisfactory completion of ground and flight training in EFVS operations to touchdown and rollout by the U.S. Armed Forces.

(2) The training requirements in paragraphs (a) and (b) of this section applicable to EFVS operations conducted under §91.176(b) of this chapter do not apply to a military pilot or former military pilot in the U.S. Armed Forces if that person documents satisfactory completion of ground and flight training in EFVS operations to 100 feet above the touchdown zone elevation by the U.S. Armed Forces.

(3) A military pilot or former military pilot in the U.S. Armed Forces may satisfy the recent flight experience requirements of paragraph (d) of this section if he or she documents satisfactory completion of an EFVS proficiency check in the U.S. Armed Forces within 6 calendar months preceding the month of the flight, the check was conducted by a person authorized by the U.S. Armed Forces to administer the check, and the person receiving the check was a member of the U.S. Armed Forces at the time the check was administered.

(g) Use of full flight simulators. A level C or higher full flight simulator (FFS) equipped with an EFVS may be used to meet the flight training, recent flight experience, and refresher training requirements of this section. The FFS must be evaluated and qualified for EFVS operations by the Administrator, and must be:

(1) Qualified and maintained in accordance with part 60 of this chapter, or a previously qualified device, as permitted in accordance with §60.17 of this chapter;

(2) Approved by the Administrator for the tasks and maneuvers to be conducted; and

(3) Equipped with a daylight visual display if being used to meet the flight training requirements of this section.

(h) Exceptions. (1) A person may manipulate the controls of an aircraft during an EFVS operation without meeting the requirements of this section in the following circumstances:

(i) When receiving flight training to meet the requirements of this section under an approved training program, provided the instructor meets the requirements in this section to perform the EFVS operation in the category of aircraft for which the training is being conducted.

(ii) During an EFVS operation performed in the course of satisfying the recent flight experience requirements of paragraph (d) of this section, provided another individual is serving as pilot in command of the aircraft during the EFVS operation and that individual meets the requirements in this section to perform the EFVS operation in the category of aircraft in which the flight is being conducted.

(iii) During an EFVS operation performed in the course of completing EFVS refresher training in accordance with paragraph (e) of this section, provided the instructor providing the refresher training meets the requirements in this section to perform the EFVS operation in the category of aircraft for which the training is being conducted.

(2) The requirements of paragraphs (a) and (b) of this section do not apply if a person is conducting a flight or series of flights in an aircraft issued an experimental airworthiness certificate under §21.191 of this chapter for the purpose of research and development or showing compliance with regulations, provided the person has knowledge of the subjects specified in paragraph (a)(2) of this section and has experience with the tasks specified in paragraph (b)(2) of this section applicable to the EFVS operations to be conducted.

(3) The requirements specified in paragraphs (d) and (e) of this section do not apply to a pilot who:

(i) Is employed by a part 119 certificate holder authorized to conduct operations under part 121, 125, or 135 when the pilot is conducting an EFVS operation for that certificate holder under part 91, 121, 125, or 135, as applicable, provided the pilot conducts the operation in accordance with the certificate holder's operations specifications for EFVS operations;

(ii) Is employed by a person who holds a letter of deviation authority issued under §125.3 of this chapter when the pilot is conducting an EFVS operation for that person under part 125, provided the pilot is conducting the operation in accordance with that person's letter of authorization for EFVS operations; or

(iii) Is employed by a fractional ownership program manager to conduct operations under part 91 subpart K when the pilot is conducting an EFVS operation for that program manager under part 91, provided the pilot is conducting the operation in accordance with the program manager's management specifications for EFVS operations.

(4) The requirements of paragraphs (a) and (b) of this section do not apply if a person is conducting EFVS operations under §91.176(b) of this chapter and that person documents that prior to March 13, 2018, that person satisfactorily completed ground and flight training on EFVS operations to 100 feet above the touchdown zone elevation.

[G450 Aircraft Operating Manual §01-34-80]

Pilot’s Manuals: The HUD section of the G450 Operating Manual (Chapter 2B: PlaneView System, Basic Issue or later approved revision) must be immediately available to the flight crew whenever use of the EVS system is contemplated.
Presence of Visual Cues: At 100 feet HAT, visual cues must be seen without the aid of EVS to continue descent to landing.
Qualifications For Use: EVS may be used only by qualified pilots who have been trained in accordance with requirements listed in the FAA GIV-X/GV/GV-SP FSB report.
Vertical Guidance Requirements For IMC EVS Approaches: Flight Director or autopilot with vertical guidance, either ILS glideslope or FMS vertical path, is required for all IMC EVS approaches.
Requirements: EVS as installed meets the requirements of EFVS (Enhanced Flight Vision System) as defined in FAR 91.175.

Flight Planning

If you have an OpSpec, MSpec, or LOA that gives you EFVS operational minimums, your dispatch rules can change to allow you to "rely" on the EFVS to those minimums. Without the authorizations your rules remain the same. If, for example, your company allows you to begin and continue the approach below published minimums and land if you see the runway, you can continue to do so. (Provided you see the necessary visual references.) My company rules, as another example, do not permit this and we would not begin or continue the approach if the weather falls below published minimums.

Flight Planning for Parts 91 and 91K Operators.

[AC 90-106A, ¶3.1] Flight planning for the purpose of conducting an EFVS operation is the same as flight planning for any other approach and must consider the forecast weather at the destination. The fuel requirements for flight in IFR conditions specified in § 91.167 apply to EFVS operations.

Flight Planning for Parts 121, 125, and 135 Operators.

[AC 90-106A, ¶3.2] To minimize the potential of not being able to visually acquire the runway and complete an approach during poor visibility conditions, part 121, 125, and 135 operators are prohibited from beginning or continuing an approach procedure when the reported visibility is less than that prescribed for the instrument approach (refer to §§ 121.651, 125.325, 125.381, and 135.225). To minimize the risk of diverting, these operators also can only dispatch a flight, release a flight or takeoff under IFR when the forecast weather is at or above the authorized minimums at the estimated time of arrival at the airport or airports to which the operator has been dispatched or released (refer to §§ 121.613, 125.361, and 135.219). This same operating principle applies to EFVS operations. A part 121, 125, or 135 operator may dispatch a flight, release a flight, or take off under IFR for the purpose of conducting an EFVS operation when the forecast weather is at or above the authorized EFVS operational minimums at the estimated time of arrival at the airport or airports to which the operator has been dispatched or released. Therefore, they can be reasonably assured that the pilot will be able to see the required visual references using the EFVS at the destination. The demonstrated performance of the EFVS defines the EFVS operational minimums specified in the operator’s OpSpec or LOA for EFVS operations. The OpSpec for part 121, 125, or 135 operators and the LOA for part 125 Letter of Deviation Authority (LODA) holders authorizes a visibility for dispatching or releasing a flight and for beginning or continuing an approach.

Approved Approaches

Provided you have the necessary authorizations: You can fly any straight in approach using EFVS down to 100 feet above the TDZE, and you can fly any straight in precision or APV approach to touchdown and rollout.

Approaches Approved for EFVS Operations to 100 Feet Above the TDZE.

[AC 90-106A ¶4.2.2]

A pilot may conduct an EFVS operation to 100 feet above the TDZE on any SIAP or special IAP, except for a circling approach. The EFVS may not be used to satisfy the § 91.175(e)(2) requirement that an identifiable part of the airport be distinctly visible to the pilot during a circling maneuver at or above MDA or while descending below MDA from a circling maneuver, or for conducting a visual approach. The pilot must accomplish this using natural vision. A pilot may use an EFVS to supplement natural vision and improve situation awareness at any time.
Instrument approach criteria, procedures, and appropriate visual references have not yet been developed for straight-in landing operations below DA/DH or MDA under IFR to heliports or platforms. EFVS cannot be used in lieu of natural vision to descend below published minimums on copter approaches to a PinS followed by a “proceed VFR” visual segment, or on approaches designed to a specific landing site using a “proceed visually” visual segment. Currently, EFVS operations in rotorcraft can be conducted only on IAPs that are flown to a runway.
Operators who have been issued OpSpec C073, MSpec MC073, or LOA C073 may conduct EFVS operations to 100 feet above the TDZE on certain NPAs that use an MDA as a DA/DH in accordance with C073.
C073 is "Vertical Navigation (VNAV) Instrument Approach Procedures (IAP) Using Minimum Descent Altitude (MDA) as a Decision Altitude (DA) / Decision Height (DH)."

Approaches Approved for EFVS Operations to Touchdown and Rollout.

[AC 90-106A ¶4.1.2]

A pilot may conduct an EFVS operation to touchdown and rollout on any Standard Instrument Approach Procedure (SIAP) or special IAP provided the minimums used for the particular approach to be flown include a DA or DH (e.g., precision or APV approach).
A pilot is not permitted to conduct EFVS operations on an instrument approach that has a circle-to-land maneuver. The EFVS may not be used to satisfy the § 91.175(e)(2) requirement that an identifiable part of the airport be distinctly visible to the pilot during a circling maneuver at or above MDA or while descending below MDA from a circling maneuver, or for conducting a visual approach. The pilot must accomplish this using natural vision. A pilot may use an EFVS to supplement natural vision and improve situation awareness at any time.
Instrument approach criteria, procedures, and appropriate visual references have not yet been developed for straight-in landing operations below DA/DH under IFR to heliports or platforms. EFVS cannot be used in lieu of natural vision to descend below published minimums on copter approaches to a point in space (PinS) followed by a “proceed visual flight rules (VFR)” visual segment, or on approaches designed to a specific landing site using a “proceed visually” visual segment. Currently, EFVS operations in rotorcraft can be conducted only on IAPs that are flown to a runway.
Under § 91.176(a), operators who have been issued OpSpec C073, MSpec MC073, or LOA C073, Vertical Navigation (VNAV) Instrument Approach Procedures (IAP) Using Minimum Descent Altitude (MDA) as a Decision Altitude (DA)/Decision Height (DH), may conduct EFVS operations to touchdown and rollout on certain non-precision Approaches (NPA) that use an MDA as a DA/DH in accordance with C073.
Sections 91.176 and 91.189 permit an authorized EFVS operation to be conducted during an authorized CAT II or CAT III operation.

Visibility Requirements

If you can see the necessary visual references using EFVS, you have "enhanced flight visibility" and can descend to 100 feet above TDZE. If you can see the necessary visual references without the EFVS, you have "natural vision" visibility and can continue.

Enhanced Flight Visibility Requirements for EFVS Operations to 100 Feet Above the TDZE.

[AC 90-106A ¶4.2.3]

For EFVS operations to 100 feet above the TDZE conducted under §§ 91.176, 121.651, 125.381, and 135.225, no person may conduct an EFVS operation in an aircraft, except a military aircraft of the United States, at any airport below the authorized DA/DH or MDA to 100 feet above the TDZE unless the pilot determines that the enhanced flight visibility observed by use of an EFVS is not less than the visibility prescribed in the IAP the pilot is using. The EFVS requirements for enhanced flight visibility under § 91.176(b) were constructed to be analogous to the flight visibility requirements for natural vision under § 91.175(c). To descend below DA/DH or MDA using natural vision under § 91.175(c), a pilot must make a determination that the flight visibility observed from the flight deck is not less than what is prescribed in the IAP being flown. To descend below DA/DH or MDA using an EFVS under § 91.176(b), a pilot must make a determination that the enhanced flight visibility observed by using an EFVS is not less than what is prescribed by the IAP being flown. The difference between determining flight visibility and enhanced flight visibility is in what the pilot uses to make the determination. In one case, the pilot is using natural vision. In the other case, the pilot is using an EFVS.
It is important to understand that, for a prescribed visibility value, the “sight picture” of the relevant visual references that the pilot can see looking forward along the flightpath from the flight deck should be similar whether the pilot is using natural vision or an EFVS. An EFVS often produces the required enhanced flight visibility when the reported visibility or the visibility observed using natural vision is much less. The point of this discussion is that even though the reported visibility or the visibility observed using natural vision may be less, as long as the EFVS provides the required enhanced flight visibility and a pilot meets all of the other requirements, the pilot can continue descending below DA/DH or MDA using the EFVS. Pilots should receive training on how to assess enhanced flight visibility and the “sight picture” for relevant visual references. How much of the forward scene, consisting of the ALS or other elements, a pilot sees at DA/DH or MDA under prescribed visibility conditions depends on individual IAP construction (geometry, TCH, slant range distance from the flight deck to relevant visual references, etc.), cockpit cutoff angle, and other relevant factors. As visibility conditions decrease, the ability of an EFVS to “see through” those conditions may also decrease depending on what type of EFVS sensor technology is used. It is important to note that there are differences in the appearance and configuration of ALSs and these should be discussed during training as well as during approach briefs. It is the pilot’s responsibility to ensure the enhanced flight visibility is adequate to safely perform the EFVS operation being conducted.
At and below 100 feet above the TDZE, a pilot must transition to natural vision to identify the required visual references in order to continue descending. In this portion of the visual segment, the flight visibility using natural vision has to be sufficient for one of the required visual references specified in § 91.176(b)(3)(iii) to be distinctly visible and identifiable. The enhanced flight visibility requirement, based on the visibility for the IAP, also applies below 100 feet even though the EFVS cannot be used to identify required visual references below 100 feet.

Enhanced Flight Visibility Requirements for EFVS Operations to Touchdown and Rollout.

[AC 90-106A ¶4.1.3]

For EFVS operations to touchdown and rollout conducted under §§ 91.176, 121.651, 125.381, and 135.225, no person may conduct an EFVS operation in an aircraft, except a military aircraft of the United States, at any airport below the authorized DA/DH to touchdown and rollout, unless the pilot determines that the enhanced flight visibility observed by use of an EFVS is not less than the visibility prescribed in the IAP the pilot is using. The EFVS requirements for enhanced flight visibility under § 91.176(a) were constructed to be analogous to the flight visibility requirements for natural vision under § 91.175(c). To descend below DA/DH or MDA using natural vision under § 91.175(c), a pilot must make a determination that the flight visibility observed from the flight deck is not less than what is prescribed in the IAP being flown. To descend below DA/DH using an EFVS under § 91.176(a), a pilot must make a determination that the enhanced flight visibility observed by using an EFVS is not less than what is prescribed by the IAP being flown. In terms of determining flight visibility or enhanced flight visibility, the difference is in what the pilot uses to make the determination. In one case, the pilot is using natural vision. In the other case, the pilot is using an EFVS.
Understanding the regulatory basis for determining flight visibility and enhanced flight visibility is important. On January 8, 1981, the FAA published 46 FR 2291, Takeoff and Landing Minimums, in which it clarified the conditions under which a pilot may approach and land at an airport when the weather conditions do not allow the pilot to see the runway until shortly before landing (46 FR 2291, at 2287-88). The determination of flight visibility is a separate action from that of identifying required visual references, and is different from ground-reported visibility. Suitable flight visibility is necessary to ensure the aircraft is in a position to continue the approach and land, and to see and avoid any obstructions in the visual segment. On January 9, 2004, the FAA published 69 FR 1620, in which it set forth the requirement for a pilot to determine enhanced flight visibility before descending below DA/DH or MDA. The rationale for determining enhanced flight visibility in the 2004 final rule is similar to the rationale for determining flight visibility in the 1981 final rule. Additionally, the regulatory requirements and pilot tasks associated with both types of operations are similar.
It is important to understand that, for a prescribed visibility value, the “sight picture” of the relevant visual references that the pilot can see looking forward along the flightpath from the flight deck should be similar whether the pilot is using natural vision or an EFVS. Even though the reported visibility or the visibility observed using natural vision may be less, as long as the EFVS provides the required enhanced flight visibility and a pilot meets all of the other requirements, the pilot can continue descending below DA/DH using the EFVS. Pilots should receive training on how to assess enhanced flight visibility and what the “sight picture” of relevant visual references should be. How much of the forward scene, consisting of the Approach Light System (ALS) or other elements, a pilot sees at DA/DH under prescribed visibility conditions depends on individual IAP construction (geometry, threshold crossing height (TCH), slant range distance from the flight deck to relevant visual references, etc.), cockpit cutoff angle, and other relevant factors. As visibility conditions decrease, the ability of an EFVS to “see through” those conditions may also decrease depending on what type of EFVS sensor technology is used. It is important to note that there are differences in the appearance and configuration of ALSs and these should be discussed during training as well as during approach briefs. It is the pilot’s responsibility to ensure the enhanced flight visibility is adequate to safely perform the EFVS operation being conducted.
The enhanced flight visibility requirement for EFVS operations to touchdown and rollout under § 91.176(a) is also applicable to that portion of the visual segment at and below 100 feet above the TDZE. That is, the enhanced flight visibility cannot be less than what is specified in the IAP being flown from DA/DH through touchdown and rollout.

Pilot Monitoring

In a two-pilot cockpit, one pilot uses the HUD and the other must monitor with a provided display.

[AC 90-106A, ¶4.2.6.1] If the aircraft is equipped with a display of sensor imagery for the PM, an operator should develop procedures for using the display, and the PM should receive training on those procedures.

The FAR goes even further as to say the PM must use the display. See: Regulatory: 14 CFR 91.176 (a)(2)(iv).

Stable Approach Requirements

The Continuous Descent Final Approach (CDFA) is the way to go, most easily accomplished with VNAV or other path automation. More about this: CDFA. If the approach doesn't line up perfectly with the runway, you should consider the lateral limits of your HUD and the associated EFVS before proceeding.

[AC 90-106A, ¶4.3.3] NPA design may require pilots to comply with more than one minimum altitude during the Final Approach Segment (FAS). Descending to each minimum altitude, and leveling off at that altitude requires multiple thrust, pitch, and altitude adjustments inside the final approach fix (FAF), thereby increasing pilot workload and the potential for error during a critical phase of flight. This practice, commonly referred to as “dive and drive,” can result in extended level flight as low as 250 feet above the obstacle environment in instrument meteorological conditions (IMC). The concept of a stabilized approach has been widely promoted as a means to help eliminate controlled flight into terrain (CFIT). The goal is to have the aircraft in the proper landing configuration, at the proper approach speed, and on the proper flightpath before descending below the minimum stabilized approach height. AC 91-79, Mitigating the Risks of a Runway Overrun Upon Landing, considers minimum stabilized approach height to be 1000 feet above the airport elevation or TDZE during IMC.

[AC 90-106A, ¶4.3.4.1] Criteria contained in the U.S. Standard for Terminal Instrument Procedures (TERPS) permit IAPs to be offset from the runway centerline (RCL). A non-Area Navigation (RNAV) NPA, for example, can be offset up to 30 degrees from the RCL and cross the final approach course up to 5200 feet from the runway threshold. A Global Positioning System (GPS) or RNAV (GPS) approach with lateral navigation (LNAV) or LNAV/vertical navigation (VNAV) minimums can be offset as much as 15 degrees from the RCL, and an instrument landing system (ILS) or localizer performance with vertical guidance (LPV) approach can be offset as much as 3 degrees. A pilot who conducts an NPA should verify lateral alignment with the RCL before descending from the MDA because actual lateral course alignment can vary depending upon facility type, distance from the facility, or signal variations that can cause an offset from the intended course centerline.

Visual Reference Requirements

The visual reference requirements to continue to 100 feet above TDZE are similar to what you need to continue an ILS down to 100 feet, with the exception of the VGSI. For more about these requirements, see: Minimums: 91.175.

Visual Reference Requirements for EFVS Operations to 100 Feet Above the TDZE.

[AC 90-106A ¶4.2.4]

To descend below DA/DH or MDA, the following visual references specified in § 91.176(b)(3)(ii) for the runway of intended landing must be distinctly visible and identifiable to the pilot using the EFVS:
- The ALS (if installed); or
- The following visual references in both items 1 and 2 below:
  1. The runway threshold, identified by at least one of the following:
    - The beginning of the runway landing surface;
    - The threshold lights; or
    - The REILs.
  2. The TDZ, identified by at least one of the following:
    - The runway TDZ landing surface;
    - The TDZ lights;
    - The TDZ markings; or
    - The runway lights.
The main differences for an EFVS operation compared to an operation using natural vision are that the VGSI lights cannot be used as a visual reference, and the pilot must be able to see both the threshold and TDZ if the approach lights are not visible.
At 100 feet above the TDZE of the runway of intended landing and below that altitude, the pilot must be able to distinctly see and identify one of the following visual references specified in § 91.176(b)(3)(iii) without reliance on the EFVS:
1. The runway threshold;
2. The lights or markings of the threshold;
3. The runway TDZ landing surface; or
4. The lights or markings of the TDZ.
As stated above, a pilot cannot continue to descend below 100 feet above the TDZE by relying solely on the EFVS sensor image to identify the required visual references. The pilot may continue to use the EFVS as long as the pilot can see the required visual references that he or she would normally see through the windscreen with natural vision. This enables the pilot to continue to benefit from the HUD guidance and the additional situation and position awareness provided by the sensor image on the EFVS display. However, the pilot must base the decision to continue descending below 100 feet above the TDZE solely on seeing the required visual references through the EFVS display by means of natural vision.

Visual Reference Requirements for EFVS Operations to Touchdown and Rollout.

[AC 90-106A ¶4.1.4]

To descend below DA/DH, the following visual references specified in § 91.176(a)(3)(ii) for the runway of intended landing must be distinctly visible and identifiable to the pilot using the EFVS:
- The ALS (if installed); or
- The following visual references in both items 1 and 2 below:
  1. The runway threshold, identified by at least one of the following:
    - The beginning of the runway landing surface;
    - The threshold lights; or
    - The REILs.
  2. The TDZ, identified by at least one of the following:
    - The runway TDZ landing surface;
    - The TDZ lights;
    - The TDZ markings; or
    - The runway lights.
The main differences for an EFVS operation compared to an operation using natural vision are that the Visual Glide Slope Indicator (VGSI) lights cannot be used as a visual reference, and the pilot must be able to see both the threshold and TDZ if the approach lights are not visible.
At 100 feet above the TDZE of the runway of intended landing and below that altitude, the pilot using EFVS must be able to distinctly see and identify one of the following visual references specified in § 91.176(a)(3)(iii):
1. The runway threshold;
2. The lights or markings of the threshold;
3. The runway TDZ landing surface; or
4. The lights or markings of the TDZ.
A pilot who conducts an EFVS operation to touchdown and rollout can continue to descend below 100 feet relying solely on the EFVS sensor image to identify the required visual references provided the other operating requirements of § 91.176(a) are met. If the EFVS fails during any portion of the approach, the pilot may not continue unless the requirements for an approach without EFVS are satisfied. For EFVS operations to touchdown and rollout that are authorized to visibilities as low as 1000 RVR, the required visibility ensures that the pilot will have adequate natural vision to continue the approach and land once descending below 100 feet above the TDZE.

[AC 90-106A ¶4.3.7] LEDs provide maintenance and efficiency advantages compared to incandescent lights. They are used in obstruction lights and airport lighting, and are being considered for use in ALSs. Infrared (IR)-based EFVSs are not able to sense LEDs, since most of them do not emit IR radiation. An EFVS also images the runway environment and runway markings, however, all of which are visual references permitted to be used to descend below DA/DH or MDA. Pilots should be familiar with the lighting at their destination, and any corresponding limitations of their EFVS.

Go Around

If you lose sight of the required visual references, you have to go around. But this is gets complicated because the missed approach is based on starting everything at the missed approach point, which might be behind you.

During an EFVS operation to 100 feet above the TDZE.

[AC 90-106A, ¶4.2.5.1] During an EFVS operation to 100 feet above the TDZE, a pilot must initiate a go-around at or below DA/DH or MDA whenever:

The enhanced flight visibility is less than the visibility minimums prescribed for the IAP the pilot is flying;
The required visual references for the runway of intended landing are no longer distinctly visible and identifiable to the pilot using the EFVS imagery (or natural vision in the event of EFVS failure);
The required visual references for the runway of intended landing are no longer distinctly visible and identifiable to the pilot using natural vision when descending below 100 feet above the TDZE;
The aircraft is not in a position from which a descent to a landing can be made on the intended runway, at a normal rate of descent, using normal maneuvers; or
The descent rate of the aircraft would not allow touchdown to occur within the TDZ of the runway of intended landing for operations conducted under part 121 or 135.

During an EFVS operation to touchdown and rollout.

[AC 90-106A, ¶4.1.5] During an EFVS operation to touchdown and rollout, a pilot must initiate a go-around at or below DA/DH whenever:

The enhanced flight visibility is less than the visibility minimums prescribed for the IAP the pilot is flying;
The required visual references for the runway of intended landing are no longer distinctly visible and identifiable to the pilot using the EFVS imagery (or natural vision in the event of EFVS failure);
The aircraft is not in a position from which a descent to a landing can be made on the intended runway, at a normal rate of descent, using normal maneuvers; or
The descent rate of the aircraft would not allow touchdown to occur within the TDZ of the runway of intended landing.

Obstacle Clearance

If the runway in use has a VASI, PAPI, RNAV(GPS), or ILS glide path, it has been surveyed to assure obstacle clearance so long as you stay at or above the indicated glide path. Obstacles will rarely have an IR signature, they are often invisible to EFVS.

[AC 90-106A, ¶4.3.1] Additionally, pilots using an EFVS should be careful not to conclude that the flightpath is free of obstacles because no obstacles are distinctly visible in the image.

[AC 90-106A, ¶4.3.1] Visual Segment Obstacle Clearance]

To assure a safe obstacle clearance margin, certain non-precision instrument approaches may require a pilot to visually identify known obstacles near the normal approach path when maneuvering in the visual segment for landing. Because imaging sensor performance can be variable in some weather conditions, pilots using an EFVS should be careful not to conclude that the flightpath is free of obstacles because no obstacles are distinctly visible in the image. This is no different than visual performance using natural vision, which can also be variable in certain weather conditions. Additionally, a pilot must ensure that the appropriate enhanced flight visibility using an EFVS exists throughout the EFVS approach operation and that he or she can see in all directions within the EFVS field of view, not just along one sightline. It is the pilot’s responsibility to see and avoid obstacles. This section provides additional information about obstacle protection.
Precision approaches (e.g., ILS/LPV) or approaches with computed vertical paths (e.g., LNAV/VNAV) provide the highest level of safety for both obstacle clearance and controlled rate of descent. If there is no published vertical guidance to a runway, the use of the FPV and FPARC on the EFVS display may assist the pilot in flying a vertical path to the runway, but that path may not be clear of all obstacles. Since the aircraft is in the visual segment of the approach, it is incumbent on the pilot to select an appropriate vertical path. The presence of a charted vertical descent angle (VDA) does not guarantee obstacle protection in the visual segment and does not change any of the requirements for flying an NPA. The published VDA is for information only, and is strictly advisory in nature.
Additional information for the visual segment below the MDA is provided if a visual descent point (VDP) is published and descent below the MDA is started at or after the VDP. VDPs provide pilots with a reference for the optimal location to begin descent from the MDA, based on the designed VDA for the approach procedure, assuming the required visual references are visible.
The use of a VGSI can help the pilot determine if the aircraft is in a position to make a descent from the MDA or DA. However, a VGSI is predicated on seeing color, and EFVS imaging sensors do not currently image color. While color can be seen through the HUD using natural vision, an EFVS image can sometimes make it difficult to interpret the VGSI. Pilots may turn the sensor image on the HUD on or off for the display of information that provides the best situation awareness for the approach being conducted.

Figure: Eagle County RNAV (GPS)-D, from FAA AL-6403.

If the runway in use does not have a VASI, PAPI, RNAV(GPS), or ILS glide path, it may be okay (it just hasn't been surveyed) but it may be that there is an obstacle issue to consider. Take the obvious example of the RNAV(GPS)-D to Eagle County Regional. Unless the mountains to the east are radiating residual heat from the day, they will be invisible to EFVS. Flying a 3° glide path will put you 2,000 feet below the 9,860 minimum altitude 3 nm from NEPRY.

Missed Approach Obstacle Clearance

My experience tells me to be skeptical about the second two points of this advisory circular extract:

First, I wonder if having EFVS is going to lower the rate of go arounds. You will have a greater tendency to take the airplane lower than the MDA, DA/DH with the theoretical odds that the PM will see the required visual references. But in the few times this has happened to me, the PM didn't see anything and we went missed any way, but we initiated the missed at a much lower altitude.
Second, EFVS will not spot terrain or obstacles unless they are radiating heat. A cold mountain will be invisible to your FLIR.

If the missed approach procedure requires an immediate climb to avoid obstacles, I would think twice about taking the airplane below the published MDA, DA/DH.

Figure: Missed approach below published DA, from Eddie's notes.

[AC 90-106A ¶4.3.6]

The published missed approach procedure provides obstacle clearance only when the missed approach is initiated from or above the DA/DH, or at the MAP. It assumes a climb rate of 200 feet/nautical mile (NM), unless a higher climb gradient is identified on the procedure. If the pilot initiates a go-around at a point below DA/DH or after the MAP, obstacle clearance is not necessarily provided by following the published missed approach procedure.
In low-visibility conditions, the operating requirements ensure a very low go-around rate below DA/DH or after the MAP. For EFVS operations, the FPARC and FPV reduce the likelihood of a go-around caused by not being in a position to continue the approach and land. Another important component is the required flight visibility, specified as part of an EFVS touchdown and rollout approval or in the conditions to initiate the approach for part 121, 125, and 135 operators.
When initiating a go-around below DA/DH or after the MAP, the use of EFVS can significantly improve safety by enabling the pilot to see terrain or obstacles that might not be visible using natural vision alone.

Operational Approval

If you are a Part 91 (but not 91K) operator using EFVS only domestically, you don't need an LOA. Internationally, you probably need an LOA. Everyone else needs an OpSpec, MSpec, or LOA.

[AC 90-106A ¶10.2]

Authorizations for EFVS Operations to 100 Feet Above the TDZE.
The FAA requires an OpSpec/MSpec/LOA for persons conducting EFVS operations to 100 feet above the TDZE under part 91K, 121, 125, 129, or 135 (refer to § 91.176(b)(2)(vii) through (ix)). Part 91 operators (other than part 91K operators) are not required to obtain an LOA to conduct EFVS operations to 100 feet above the TDZE in the United States. Part 91 operators (other than part 91K operators) who conduct EFVS operations to 100 feet above the TDZE outside the United States may request an LOA to facilitate foreign CAA approval.
Authorizations for EFVS Operations to Touchdown and Rollout.
The FAA requires an OpSpec/MSpec/LOA for persons conducting EFVS operations to touchdown and rollout under part 91, 91K, 121, 125, or 135 (refer to § 91.176(a)(2)(viii) through (xi)). Under § 91.176(a)(2)(x), an authorization is also required for foreign air carriers subject to part 129 who wish to conduct EFVS operations to touchdown and rollout in the United States.
Additional EFVS OpSpec/LOA Provisions for Part 121, 125, and 135 Operators.
The OpSpec/LOA for part 121, 125, or 135 operators may authorize a visibility for dispatching or releasing a flight under §§ 121.613 and 121.615, releasing a flight under §§ 125.361 and 125.363, or taking off under IFR under § 135.219. The operator’s OpSpec/LOA for EFVS operations may also contain provisions for beginning or continuing an approach when the visibility is reported to be less than the visibility minimums prescribed for the IAP to be flown. To qualify for these provisions, operators who plan to conduct these operations under either § 91.176(a) or (b) should present their procedures and training for pilots, dispatchers, flight release personnel, and other personnel authorized to exercise operational control. An operator’s procedures and training should consider the limitations of the EFVS the operator will use and the weather conditions that may exceed the sensor’s ability to provide the enhanced flight visibility required to complete the approach and landing. An operator must be able to demonstrate that it has the ability to determine when it is appropriate to dispatch a flight, release a flight, or take off under IFR for the purpose of conducting an EFVS operation and that its dispatch and flight release procedures appropriately support EFVS operations.
EFVS Sensor Performance and OpSpec/LOA Provisions for Parts 121, 125, and 135 Operators.
An operator conducting EFVS operations under part 121, 125, or 135 should present EFVS sensor performance information with their proposal to conduct EFVS operations under either § 91.176(a) or (b). The sensor performance information should characterize the enhanced flight visibility or the visual advantage produced by the EFVS over a range of representative visibility and weather conditions. The operator’s authorization to dispatch, release a flight, or take off under IFR or to begin or continue an approach will be based on this sensor performance information. EFVS sensor performance information may be information that was demonstrated for the aircraft and documented in the AFM(S) or RFM(S), additional data the Original Equipment Manufacturer (OEM) or operator may have collected through an operational evaluation with respect to the EFVS sensor’s ability to perform in low visibility conditions, or other data or information the FAA might find acceptable. AC 20-167 contains additional information about EFVS performance demonstrations. The purpose of requiring EFVS sensor performance information is to increase the likelihood of a successful EFVS operation at the destination airport.

[AC 90-106A ¶10.3.2] Application Requirements for Part 91 Operators Seeking an LOA for EFVS Operations to 100 Feet Above the TDZE Outside the United States. Part 91 operators (other than part 91K operators) conducting EFVS operations to 100 feet above the TDZE outside of the United States may request an LOA from the FAA. The operator should present the FSDO or CHDO with documentation showing that the aircraft is equipped with an EFVS that meets the applicable equipment requirements of § 91.176(b)(1).

Eddie's In Box

I probably fly down to minimums just a handful of times a year and I very rarely see the runway lights through the EFVS before the other pilot does using natural vision. We have a Gulfstream HUD I with a EFVS II and the results have been mixed. I do get a fair amount of email that confirms this. Here's an example.

Dear Eddie,

I was hoping you might be able to point me in the right direction on that question I mentioned to you about the HUD/EVS issue I have had a couple of times.

The question is regarding EVS issues on low visibility approaches in fog. A few years ago I did an approach into Santiago, Chile at night with ground fog present. We entered the cloud at about 700 feet above ground level. As soon as we were in cloud, I saw what looked like cotton balls rolling across the HUD display. We descended to minimums and I didn’t acquire any lights or visual references. We executed a missed approach. The pilot in the right seat mentioned that he had seen the runway lights out the windscreen and thought that we ought to be able to get in. We went around for another approach with the HUD retracted and had no difficulty acquiring the runway environment and continued to an uneventful landing.

Last month I had an identical occurrence on approach into White Plains. We had low ground fog with RVR between 1800’ and 2000’. It was a night approach and I again in cloud, saw what looked like cotton balls rolling across the HUD/EVS display. I retracted the HUD at about 200 feet above minimums and acquired the runway environment right at minimums and continued for a landing.

In both cases, it was nighttime and the RVR was around 1800’ in fog.

In previous aircraft without HUD/EVS in similar weather conditions I have had success (at night) in turning off the landing lights to make it easier make visual contact with the approach and runway lights. In thinking back on the two previously mentioned approaches, the thought occurred to me that perhaps the EVS could be affected by light reflecting off the water molecules and reducing the effectivity of the EVS Camera. I’ve been on the airplane for eight years now and have never heard anyone mention anything like this in initial or recurrent training.

Would you be able to connect me with someone in the Gulfstream flight department that might be able to shed some light on my question?

Signed: Still Blinded by FLIR

Dear Blinded,

My experience is like yours. I did ask an engineer at Gulfstream and this is the answer I got.

The “cotton balls” are probably water drops running down the EVS window if they are transitioning from the top to bottom. This happens in fog with a lot of large drops. As far as not seeing the lights with EVS this can happen for a few reasons.

In very low visibility conditions it can be helpful to select High Gain for the EVS setting, vice the normal Auto Gain. This can help with the fog penetration.
In some rare conditions, the droplet size and moisture content of the fog will allow the wavelength of natural vision (.4 to .7 microns) to better penetrate the fog than the FLIR wavelengths (about 1 to 4.5 microns). While this is rare, it can happen.
If the brightness and contrast are not set up in a reasonable manner, the lights may be hard to see in the green background of the EVS display.
When looking through the EVS HUD, the maximum depression angle the EVS can see is about 11-13 degrees. This is where the approach lights and runway threshold lights will be. At 200 feet, this is in excess of 1,000 feet of fog to see through. If looking steeper at 200 feet, the strobes or other lights may be seen with natural vision because you may be looking through much less fog. (If you were able to look at a 30 degree angle at 200 feet, you would only be seeing through 400 feet of fog instead of the 1,000 to 1,200 feet the EVS would have to penetrate.)
If the visibility is about half the 2,400 feet vis normally required for a Cat I approach, (1,200 feet) or greater, you should be able to see the lights with the EVS and continue to at least 100 feet above touchdown. If the visibility is less than 1,200 feet the chances of EVS detecting the required items are much less, so an approach in 600 RVR is not likely to be successful.

References

14 CFR 91, Title 14: Aeronautics and Space, General Operating and Flight Rules, Federal Aviation Administration, Department of Transportation

Advisory Circular 90-106A, Enhanced Flight Vision Systems, 3/2/17, U.S. Department of Transportation

EASA Air Ops Annex 1 to VIII, European Aviation Safety Agency, 09 May 2017

Flight Standardization Board (FSB) Report, Gulfstream GIV-X, GV, GV-AP, Revision 8, 08/01/2012

Gulfstream G450 Aircraft Operating Manual, Revision 35, April 30, 2013.

ICAO Annex 6 - Operation of Aircraft - Part 1 Commercial Aircraft, International Standards and Recommended Practices, Annex 6 to the Convention on International Civil Aviation, Part I, 10th Edition, July 2016

ICAO Annex 6 - Operation of Aircraft - Part 2 General Aviation, International Standards and Recommended Practices, Annex 6 to the Convention on International Civil Aviation, Part II, 9th edition, July 2016

ICAO Annex 6 - Operation of Aircraft - Part 3 Helicopters, International Standards and Recommended Practices, Annex 6 to the Convention on International Civil Aviation, Part III, 8th edition, July 2016

ICAO Doc 9365, Manual of All Weather Operations, Third Edition - 2013, International Civil Aviation Organization