CS AWO.A.EFVS.101 General

ED Decision 2022/007/R

(a) An enhanced flight vision system (EFVS) uses an electronic means to provide a real-time display of the forward external scene topography through the use of imaging sensors.

(b) The EFVS shall provide a demonstrated vision performance in low-visibility conditions and a level of safety suitable for the proposed operational procedure that will allow the required visual references to become visible in the image before they are visible naturally out‑the‑window.

(c) The EFVS shall provide an enhanced vision image that can be used during an instrument approach to enhance the pilot’s ability to detect and identify the required visual references for landing in order to gain an operational credit and descend below the decision altitude (DA) / decision height (DH) or minimum descent altitude (MDA).

(d) The EFVS sensor imagery and required aircraft flight information and flight symbology shall be displayed on a HUD (or equivalent display) so that the imagery and symbology are clearly visible to the pilot flying in their normal position with the line of vision looking forward along the flight path. The HUD or equivalent display that is used to display the EFVS sensor imagery, aircraft flight information and flight symbology shall comply with the requirements of Subpart A Section 2.

(e) The EFVS shall include the display element, sensors, computers and power supplies, indications, and controls. It may receive inputs from an airborne navigation system or flight guidance system. The EFVS display characteristics and dynamics shall be suitable for the manual control of the aircraft.

(f) A database may be used to support the provision of a synthetic runway (or equivalent). For these databases, a consistent set of data quality requirements (DQRs) shall be established to support the intended function of the equipment. Any requirements for the databases must be described to enable operators to conduct checks before using the database. The means of processing and maintaining the database shall be defined.

[Issue 2: CS-AWO/2]

AMC AWO.A.EFVS.101 General

ED Decision 2022/007/R

The functions the enhanced flight vision system (EFVS) is intended to perform should be defined. This definition should include what features will be displayed and the criticality of pilot decision-making when using the display features. The additional intended functions (for example, terrain alerting) should be defined according to AMC 25-11 as well as CS 23.2500 and CS 25.1301.

This should include the use of the EFVS to visually acquire the visual references required to operate below the DA/H or the MDA and the criticality of pilot decision-making based on what is visible when using the EFVS display. The purpose of the EFVS is to provide a visual advantage over the pilot’s out‑the-window view using natural vision. In low-visibility conditions, the ‘enhanced flight visibility’ should exceed the ‘flight visibility’, and the required visual references should become visible to the pilot at a longer distance with an EFVS than they would be out-the-window using natural vision. The visual advantage of using an EFVS should be demonstrated before descending below the DA/H or the MDA because this is the point in an instrument approach procedure where the operating rules permit an EFVS to be used in lieu of natural vision for operational benefits.

Note 1: The EFVS is not intended to replace the technologies or procedures already used to safely fly the aircraft down to the MDA/H or the DA/H.

Note 2: While the goal of the EFVS is to exceed the natural flight visibility in the majority of cases / weather conditions, there may be meteorological conditions where the EFVS does not provide a significant advantage.

Note 3: The HUD (or equivalent display) is separately certified and should remain subject to all applicable rules and guidance for a given category of aircraft and operation.

Databases that are used to support the provision of a synthetic runway (or equivalent) that are provided by a Type 2 DAT provider certified in accordance with Regulation (EU) 2017/373³ Commission Implementing Regulation (EU) 2017/373 of 1 March 2017 laying down common requirements for providers of air traffic management/air navigation services and other air traffic management network functions and their oversight, repealing Regulation (EC) No 482/2008, Implementing Regulations (EU) No 1034/2011, (EU) No 1035/2011 and (EU) 2016/1377 and amending Regulation (EU) No 677/2011 (OJ L 62, 8.3.2017, p. 1). or equivalent, and that are compliant with the data quality requirements (DQRs) are considered to be an acceptable means of compliance to CS AWO.A.EFVS.101(f).

Note: For databases, the applicant should identify the DQRs during the airworthiness approval and demonstrate that they are consistent with the intended function of the equipment.

[Issue 2: CS-AWO/2]

CS AWO.A.EFVS.102 Enhanced flight vision system designation

ED Decision 2022/007/R

(a) An enhanced flight vision system — approach (EFVS-Approach (EFVS-A)) is a system that has been demonstrated to meet the criteria to be used for approach operations from a DA/H or an MDA to 30 m (100 ft) touchdown zone elevation (TDZE) whilst all system components function as intended, but may have failure modes that could result in the loss of the EFVS capability. It shall be assumed for an EFVS-A that:

(1) the pilot will conduct a go-around above 30 m (100 ft) TDZE, in the event of an EFVS failure; and

(2) descent below 30 m (100 ft) above the TDZE through to touchdown and roll-out shall be conducted using natural vision in order that any failure of the EFVS shall not prevent the pilot from completing the approach and landing.

(b) An enhanced flight vision system — landing (EFVS-Landing (EFVS-L)) is a system that has been demonstrated to meet the criteria to be used for approach and landing operations that rely on sufficient visibility conditions to enable unaided roll-out and to mitigate for the loss of the EFVS function.

Note: When a HUD (or equivalent display) is used for an EFVS-L, it does not necessarily have to comply with the HUDLS requirements.

(c) An EFVS that meets the certification criteria for an EFVS-L shall be considered to have met the certification criteria for an EFVS-A.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.103 Enhanced flight vision system depiction

ED Decision 2022/007/R

(a) The enhanced flight vision system (EFVS) sensor imagery and the following flight symbology shall be presented so that they are aligned with and scaled to enable a one-to-one (conformal) overlay with the actual external scene:

(1) aircraft attitude;

(2) command guidance as appropriate for the approach to be flown;

(3) flight path vector (FPV);

(4) flight path angle reference cue (FPARC), and other cues, which are referenced to this imagery and external scene topography; and

(5) the means required by CS AWO.A.EFVS.105(b).

(b) The FPARC shall be suitable for monitoring the vertical flight path of the aircraft on approaches without vertical guidance and shall be displayed referenced to the pitch scale. It shall be possible for the pilot to be able to set the FPARC to the desired descent angle for the approach. The descent angle may also be automatically set to a value found in an on-board database.

(c) The displayed EFVS imagery and aircraft flight symbology shall not adversely obscure the pilot’s outside view or field of view (FOV) through the cockpit window and shall be free of interference, distortion, and glare that would adversely affect the pilot’s normal performance and workload.

(d) The EFVS-L shall provide a means of providing a flare cue and shall use a radio altimeter (or other device capable of providing equivalent performance and integrity level) to determine height above terrain.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.103 EFVS depiction

ED Decision 2022/007/R

The EFVS image is in the centre of the pilot’s regulated ‘pilot compartment view’. It should be free of interference, distortion, and glare that would adversely affect the pilot’s normal performance and workload. A video image can be more difficult for the pilot to see through than symbols that are also displayed on the HUD. Unlike symbology, the video image illuminates, to some degree, most of the total display area of the HUD with much greater potential interference with the pilot compartment view. It is sufficient for the pilot to see around the video image, but the outside scene must be visible through and around it.

Unlike the pilot’s external view, the EFVS image is a monochrome, two-dimensional display. Some, but not all, of the depth cues found in the natural view are also found in the imagery. The quality of the EFVS image and the level of the EFVS sensor performance could depend significantly on the atmospheric and external light source conditions. Gain settings of the sensor, and brightness or contrast settings of the HUD (or equivalent display), can significantly affect image quality. Certain system characteristics could create distracting and confusing display artefacts. Finally, this is a sensor-based system that is intended to provide a conformal perspective.

The sensor image, combined with the required aeroplane state and position reference symbology, is presented to the flight crew on a HUD (or an equivalent display), so that they are clearly visible to the pilot flying in their normal position and line of vision looking forward along the flight path.

The integration of the major components should include the installed sensor, its interconnections with the sensor display processor, the display device, pilot interface, and aircraft mechanical interface, which can include the radome for the sensor.

Flare cue

An EFVS-L should have a flare cue because it is intended to enable landing in low visibility. As regards flare cue, whether a flare prompt or flare guidance, its compliance with AMC AWO.A.HUD.107 should be demonstrated.

Flare guidance provides explicit command guidance for the pilot to flare the aircraft.

A flare prompt advises the pilot when it is time to begin making the control inputs for the flare manoeuvre and transition to landing. A flare prompt does not provide command guidance for manoeuvring the aeroplane with regard to the rate or magnitude of manual inputs, alignment to runway heading nor touching down at a specific point on the runway.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.104 Enhanced flight vision system display

ED Decision 2022/007/R

(a) The display of the enhanced flight vision system (EFVS) image on the HUD (or equivalent display) shall not hinder or compromise the pilot’s ability to see and use the required primary flight display information.

(b) The field of regard (FOR) of the HUD (or other equivalent display) shall be sufficient for the EFVS information to be displayed conformally over the range of anticipated aircraft attitudes, aircraft configurations, and environmental (including wind) conditions for each mode of operation.

(c) The EFVS FOR shall be appropriate for the intended operation and function, and shall take into consideration:

(1) the HUD (or equivalent display) and the EFVS sensor FOV;

(2) the orientation of the HUD (or equivalent display) with respect to the aircraft frame of reference; and

(3) the orientation of the aircraft.

(d) The EFVS FOR shall be checked during certification flight test for sufficiency in meeting its intended function.

(e) When a minimum flight crew of more than one pilot is required for the conduct of the intended operation, a suitable display EFVS sensor imagery shall be provided to the pilot monitoring in order to monitor and assess the safe conduct of the approach, and for EFVS-L the landing and also the roll-out. The intended use of the monitoring display shall be defined and, if needed, the symbology that need to be displayed shall be derived.

Note: The intended use may include consistency checks and mitigation for failure conditions as per the FHA. The purpose of the consistency check is to ensure that the aircraft position and attitude and speed are correct and that the pilot monitoring can verify and anticipate the safe continuation of the approach leading to a landing in the touchdown zone using normal manoeuvres.

(f) The EFVS image shall be compatible with the field of view (FOV) and head motion box of the HUD.

(g) A previously certified HUD (or equivalent display) that is used to display EFVS shall continue to meet the conditions of the original approval and shall be adequate for the intended function, in all phases of flight in which the EFVS is used.

(h) The EFVS display shall permit the pilot to accurately and easily recognise unusual aircraft attitude (and other abnormal manoeuvres) and initiate a timely recovery.

(i) The latency of the EFVS display shall be minimised and shall not be confusing or misleading to the pilot, and shall not affect control performance or increase pilot workload.

(j) The EFVS shall minimise the potential for misleading or distracting imagery by precluding off-axis information from folding into the primary FOR imagery.

(k) The displayed EFVS image jitter amplitude shall be appropriate and minimised, and shall not exhibit jitter greater than that of the HUD (or equivalent display) that it is displayed on.

(l) The displayed EFVS image flicker shall be appropriate and minimised, and shall not exhibit flicker greater than that of the HUD (or equivalent display) that it is displayed on.

(m) The EFVS shall not exhibit any objectionable noise, local disturbances or an artefact that are hazardously misleading and/or detract from the use of the system.

(n) The accuracy of the integrated EFVS and HUD (or equivalent display) image shall be appropriate for the intended function and operation.

(o) Any passive sensor optical distortion shall be appropriate for the intended function and operation.

(p) The EFVS sensor shall provide a means to minimise blooming and shall prevent blooming that results in the required visual references no longer being distinctly visible and identifiable.

(q) The EFVS image persistence time shall be appropriate for the intended function and operation.

(r) Dead pixels shall be minimised and shall be of a total area appropriate for the intended function and operation.

(s) The effects of parallax caused by lateral, vertical, and longitudinal offset of the sensor from the pilots’ design eye position shall not impede the EFVS from performing its intended function, and shall not result in significant performance differences in unsatisfactory landing or safety-related performance parameters between EFVS operations and visual operations in the same aircraft.

(t) The EFVS-A display that provides imagery to the pilot monitoring shall:

(1) be located so that it is plainly visible to the pilot monitoring from their station with the minimum practicable deviation from their normal position and line of vision when the pilot looks forward along the flight path, and any symbology displayed shall not adversely obscure the sensor imagery of the runway environment;

(2) provide an image of the visual scene over the range of aircraft attitudes and wind conditions for each mode of operation, and enable the pilot monitoring to support effective flight crew tasks for the operation;

(3) not require the pilot monitoring to unduly move their head/body away from their normal scan pattern or their normal seated position; and

(4) ensure satisfactory display of imagery in all lighting and environmental conditions, and that dimming controls of the display are adequate.

(u) The EFVS-L display that provides imagery to the pilot monitoring shall:

(1) be centred as nearly as practicable about the vertical plane of the pilot’s forward vision;

(2) be located so that the pilot monitoring seated at the controls can monitor the aeroplane’s flight path and instruments with minimum head and eye movement;

(3) provide an image of the visual scene over the range of aircraft attitudes and wind conditions for each mode of operation, and enable the pilot monitoring to see and identify visual references and to verify that all visual requirements for the approach and landing are satisfied;

(4) not require the pilot monitoring to unduly move their head/body away from their normal scan pattern or their normal seated position; and

(5) ensure satisfactory display of imagery in all lighting and environmental conditions, and that dimming controls of the display are adequate.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.104 EFVS display

ED Decision 2022/007/R

The EFVS imagery should not degrade the presentation of essential flight information on the HUD. The pilot’s ability to see and use the required primary flight display information, such as primary attitude, airspeed, altitude, and command bars, should not be hindered or compromised by the EFVS image on the HUD.

The EFVS imagery displayed on the HUD or equivalent display must account for the pilot compartment view requirements found in CS 25.773 or CS 23.2600, including validation that the display of imagery does not conflict with the pilot compartment view. The display of the EFVS sensor imagery should be on a system that compensates for the interference caused by the provided imagery. Additionally, the system should provide an undistorted and conformal view of the external scene, a means to deactivate the display, and should not restrict the pilot from performing specific manoeuvres. The following tasks associated with the use of the pilot’s view should not be degraded below the level of safety that existed without the video imagery:

(a) Detection, accurate identification and manoeuvring, as necessary, to avoid traffic, terrain, obstacles, and other hazards of flight.

(b) Accurate identification and utilisation of visual references required for every task relevant to the respective phase of flight.

Note: Although the EFVS image requirements relate primarily to the approach and landing phases of flight, the EFVS image, when viewed head-up during ground operations, should not create unacceptable distraction to the pilots due to sensor proximity to the taxiway surface.

For EFVSs that are implemented on a HUD, the image should be compatible with the FOV and head motion box of a HUD designed against SAE ARP5288 Transport Category Airplane Head Up Display (HUD) Systems. When used in a given phase of flight, the HUD and the EFVS FOR must provide a conformal image with the visual scene over the range of aircraft attitudes and wind conditions.

EFVS display criteria must meet the CS-23 or CS-25 airworthiness specifications (as applicable) (see Appendix 1 to the AMC to Section 3 of Subpart A). Some of these specifications could be specific to EFVSs and could be in addition to all other requirements applicable to the HUD and the basic avionics installation. The amount of new test data can be determined by the individual application, availability, and relevance of data.

The current certification specifications for HUDs apply with respect to EFVSs. These criteria include well-established military as well as civil aviation standards for HUDs as defined in MIL-STD-1787C Aircraft Display Symbology and in AMC 25-11. SAE design standards for HUD symbology, optical elements, and video imagery are also prescribed within SAE AS8055 Minimum Performance Standard for Airborne Head Up Display (HUD), SAE ARP5288 Transport Category Airplane Head Up Display (HUD) Systems, and SAE ARP5287 Optical Measurement Procedures for Airborne Head Up Display (HUD). The specific design standards for image size, resolution and line width, luminance and contrast ratio, chromaticity, and grayscale should be applied.

A HUD modified to display EFVS imagery should continue to meet the conditions of the original approval and be adequate for the intended function in all phases of flight in which the EFVS is used. An accurate, easy, quick-glance interpretation of attitude should be possible for all unusual attitude situations and other ‘non-normal’ manoeuvres to permit the pilot to recognise the unusual attitude and initiate recovery within 1 second. The use of chevrons, pointers, and/or permanent ground-sky horizon on all attitude indications to perform effective manual recovery from unusual attitudes is recommended. Refer to AMC 25-11 for guidance on electronic flight deck displays.

EFVS latency should be no greater than 100 milliseconds (ms). Latency should not be discernible to the pilot and should not affect control performance nor increase pilot workload. EFVS latency causes, at best, undesirable oscillatory image motion in response to pilot control inputs or turbulence. At worst, EFVS latency may cause pilot-induced oscillations if the pilot attempts to use the EFVS for active control during precision tracking tasks or manoeuvres in the absence of other visual cues.

EFVS field of regard (FOR)

The minimum fixed FOR should be 20 degrees horizontally and 15 degrees vertically. In applications where the FOR is centred on the flight path vector (FPV), the minimum vertical FOR should be 5 degrees (± 2.5 degrees) and 20 degrees horizontally.

(a) The minimum EFVS FOR should not only consider the HUD FOV (i.e. the size of the area that is displayed), but also the area over which this area subtends (i.e. what is shown on the conformal display). The FOR portrayed on the HUD is established by three primary aspects:

(1) HUD and EFVS sensor FOV;

(2) orientation of the HUD with respect to the aircraft frame of reference (for example, boresight and proximity to pilot’s eye); and

(3) orientation (for example, attitude) of the aircraft, if FOR is centred on FPV.

(b) SAE ARP5288 Transport Category Airplane Head Up Display (HUD) Systems states: ‘The design of the HUD installation should provide adequate display fields-of-view in order for the HUD to function correctly in all anticipated flight attitudes, aircraft configurations, or environmental conditions such as crosswinds for which it is approved. Limitations should be clearly specified in the AFM if the HUD cannot be used throughout the full aircraft flight envelope.’

A quantitative EFVS FOR should be established as a minimum design criterion to be qualitatively checked during the certification flight test for sufficiency in meeting its intended function. The EFVS FOR should result from consideration of the minimum FOR criteria for various aircraft attitudes and wind conditions using a critical altitude of 200 ft height above TDZE for EFVS visibility.

(c) A variable FOR is permissible assuming a slewable sensor (i.e. variable FOR), centred on the FPV, with a minimum ±2.5 degrees about the FPV to allow for momentary flight path perturbations and to allow for sufficient fore/aft view of the required visual references.

Off-axis rejection

A source in object space that is greater than 1 degree outside the FOV should not result in any perceptible point or edge-like image within the FOV. The EFVS should preclude off-axis information from folding into the primary FOR imagery, creating the potential for misleading or distracting imagery.

Jitter

When viewed from the HUD eye reference point, the displayed EFVS image jitter amplitude should be less than 0.6 mrad. Jitter for this use is defined in SAE ARP5288. This implies that the EFVS and the HUD cannot exhibit jitter greater than that of the HUD itself.

Flicker

Flicker is brightness variations at frequency above 0.25 Hz as per SAE ARP5288. The minimum standard for flicker should meet the criteria of SAE ARP5288. Flicker can cause mild fatigue and reduced crew efficiency. Therefore, the EFVS and the HUD should not exhibit flicker greater than that of the HUD itself.

Image artefacts

The EFVS should not exhibit any objectionable noise, local disturbances, or an artefact that prevents the system from meeting its intended function. The EFVS design should minimise display characteristics or artefacts (for example, internal system noise, ‘burlap’ overlay, or running water droplets) which obscure the desired image of the scene, impair the pilot’s ability to detect and identify visual references, mask flight hazards, distract the pilot, or otherwise degrade task performance or safety.

Image conformality

The accuracy of the integrated EFVS and HUD image should not result in a greater than 5 mrad display error at the centre of the display at a range of 2 000 ft (100 ft altitude on a 3-degree glideslope). In accordance with SAE ARP5288, the total HUD system display accuracy error, as measured from the HUD eye reference point, should be less than 5.0 mrad at the HUD boresight, with increasing error allowable toward the outer edges of the HUD. Errors away from the boresight should be as defined in SAE ARP5288. The primary EFVS error components include the installation misalignment of the EFVS sensor from aircraft/HUD boresight and sensor parallax. A range parameter is used in the EFVS conformability requirement to account for the error component associated with parallax. There is no error allowed for the EFVS sensor, since it is assumed that any error can be electronically compensated during installation. With EFVS operations, the aircraft is flown essentially irrespective of the EFVS/HUD dynamic error, to the MDA or DA. From this point to 100 ft height above TDZE, the EFVS conformality error introduces error in the pilot’s ability to track along the extended centre line / vertical glide path as the pilot flies the FPV and glide path reference line toward the EFVS image of the runway.

Dynamic range

The minimum required dynamic range for passive EFVSs should be 48 dB. For active EFVSs, side lobes should be 23 dB below the main beam, and 40 dB dynamic range plus sensitivity time control.

Sensor image calibration

Visible image calibrations and other built-in tests that cannot be achieved within a total latency of 100 ms should occur only either on pilot command or be coordinated by aircraft data to only occur in non-critical phases of flight. If other than normal imagery is displayed during the non‑uniformity correction (NUC) or other built-in tests, the image should be removed from the pilot’s display. This prohibits excessive times to complete maintenance or calibration functions which would remove or degrade the EFVS imagery during critical phases of flight, unless the pilot commands the action (with full knowledge of the effect based on training and experience). Abnormal imagery should be removed from the display to eliminate the potential for any misleading information.

Passive sensor optical distortion

Optical distortion should be 5 % or less across the minimal FOR and no greater than 8 % outside the minimal FOR.

Sensor sensitivity

In this context, the EFVS sensor sensitivity should be at least a noise-equivalent temperature difference (NETD) of 50° mK tested at an appropriate ambient temperature for passive EFVSs or –20 dB sm/sm (square metre/square metre) surface at R_max from 200 ft height above TDZE with a typical 3° glideslope for active EFVSs. Passive sensors for different visible or short-wave infrared sources can require very sensitive detectors, as specified by low noise-equivalent powers.

Blooming

The sensor should incorporate features to minimise blooming, which can create an unusable or objectionable image. Objectionable blooming is defined as the condition that obscures the required visual cues. Blooming to the extent the required visual references are no longer distinctly visible and identifiable is unacceptable.

Image persistence

The image persistence time constant should be less than 100 ms. However, burn-in or longer image persistence caused by high-energy sources (for example, the sun saturating the infrared sensor elements) should be removed from the image. Image artefacts should be removed by a secondary on-demand process (for example, the non-uniformity correction (NUC) process).

Dead pixels

Dead pixels or sensor elements replaced by a ‘bad pixel’ replacement algorithm should be limited to 1 % average of the total display area, with no cluster greater than 0.02 % within the minimum FOR. A small number of disparate dead pixel elements can be effectively replaced by image processing but eventually the algorithms will degrade the image quality and accuracy due to the sheer number and closely spaced location of the element.

Parallax

The effects of parallax caused by lateral, vertical, and longitudinal offset of the sensor from the pilots’ design eye points should not impede the EFVS from performing its intended function, as evaluated during flight test. Parallax should not cause unsatisfactory landing performance parameters (e.g. flare height, sink rate, touchdown location, ground speed during landing, exit and taxiing) between EFVS operations and visual operations in the same aircraft.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.105 Head-up display enhanced flight vision system (HUD EFVS) symbology

ED Decision 2022/007/R

(a) In addition to sensor imagery, the flight instrument data that is displayed on the HUD (or equivalent display) shall, as a minimum, include:

(1) airspeed,

(2) vertical speed,

(3) aircraft attitude,

(4) heading,

(5) altitude,

(6) command guidance as appropriate for the approach to be flown,

(7) path deviation indications,

(8) FPV, and

(9) FPARC.

(b) A means shall be provided within the HUD (or equivalent display) on the approach to:

(1) enable a consistency check with the EFVS imagery and other flight information;

(2) increase awareness of the runway environment and its emergent location; and

(3) enable the expected location on the HUD (or equivalent display) of the approach and threshold lights to be identified during the particular types of approach for which certification is requested.

Such means must not be misleading, must not cause pilot confusion nor increase pilot workload, and must not occlude the emerging EFVS cues.

(c) EFVS-L that is intended to be used from the DA/H through touchdown and roll-out at not less than 300 m (1 000 ft) RVR shall also display:

(1) height AGL such as that provided by the use of a radio altimeter or other device capable of providing equivalent performance and integrity level; and

(2) a flare prompt or flare guidance for achieving acceptable touchdown performance.

(d) The appearance and dynamic behaviour of the EFVS-L flare prompt shall be distinct from any command guidance and shall appear in a timely and conspicuous manner to the pilot.

(e) An FPV shall be provided on the same display as the EFVS imagery and shall provide a position and motion that corresponds to the aircraft’s earth-referenced FPV, and shall dynamically respond to follow the pilot control inputs.

(f) The dynamic response of the FPV symbol to pilot control inputs shall not exhibit undue lag or overshoot.

(g) An FPARC shall be provided on the same display as the EFVS imagery that is suitable for monitoring the vertical path of the aircraft. A means shall be provided to permit the pilot to select the desired descent angle that is represented by the FPARC. It is also possible for the descent angle to be provided automatically from a database.

(h) The display of attitude symbology, FPV, FPARC, and other visual elements which are earth referenced, shall be aligned with, scaled and conformal to the external view.

(i) The EFVS display of imagery, flight information and flight symbology shall provide suitable visual reference for the pilot during the manual performance of any manoeuvres within the operating limitations of the aircraft, including taxiing, take-off, approach, landing and roll-out, as applicable for the intended function.

[Issue: CS-AWO/2]

AMC1 AWO.A.EFVS.105 HUD EFVS symbology

ED Decision 2022/007/R

Flare prompt

A flare prompt is intended to notify the pilot that it is time to initiate the flare manoeuvre but does not guide the pilot’s manual pitch control inputs. The pilot should use situational information (e.g. altitude, vertical rate, attitude, FPV, perspective view of the runway) from the EFVS to judge the magnitude and rate of manual pitch control inputs. The appearance and dynamic behaviour of the flare prompt should be distinguishable from command guidance. The flare prompt should appear timely and conspicuously to the pilot using the HUD so that the flare manoeuvre will be neither too early nor too late and within the TDZ as described in AMC AWO.A.EFVS.109.

[Issue: CS-AWO/2]

AMC2 AWO.A.EFVS.105(b) HUD EFVS symbology

ED Decision 2022/007/R

The provision of a conformal runway outline or synthetic runway on the HUD on approach is considered an acceptable means of enabling a consistency check of the EFVS imagery to increase awareness of the runway environment and enable the expected location of the approach lighting system to be identified.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.106 Enhanced flight vision system (EFVS) display controls

ED Decision 2022/007/R

(a) A means of controlling the EFVS display contrast/brightness shall be provided that prevents:

(1) distraction of the pilot;

(2) impairment of the pilot’s ability to detect and identify visual references;

(3) masking of flight hazards; and

(4) degradation of task performance or safety.

(b) If an automatic control means for image brightness is not provided, it shall be shown that the manual setting of image brightness meets the above criteria and does not cause excessive pilot workload.

(c) The EFVS display controls shall be visible to, and within reach of, the pilot flying from any normal seated position and shall provide a readily accessible control to permit the pilot flying to immediately deactivate or reactivate the display of the EFVS image on a HUD (or equivalent display) without requiring the pilot to remove their hands from the primary flight controls and thrust control.

(d) The position and movement of the EFVS controls shall be designed to minimise the likelihood of inadvertent operation.

(e) With the exception of controls located on the pilot’s control wheel (or equivalent), EFVS controls shall be adequately illuminated for all normal background lighting conditions, and shall not create any objectionable reflections on the HUD (or equivalent display) or other flight instruments.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.106 EFVS display controls

ED Decision 2022/007/R

There should be a means to allow the pilot using the display to immediately deactivate and reactivate the vision system imagery, on demand, without requiring the pilot to remove their hands from the primary flight and power controls, or their equivalent controls.

The EFVS installation and image should have an effective control of the EFVS display brightness without causing excessive pilot workload nor adverse physiological effects such as fatigue or eye strain.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.107 Enhanced flight vision system (EFVS) safety assessment

ED Decision 2022/007/R

(a) The normal operation of the EFVS shall not adversely affect, or be adversely affected by, other aircraft systems.

(b) A safety assessment of the installed EFVS, considered separately and in conjunction with other relevant installed systems, shall be conducted to meet the requirements of CS 23.2510 or CS 25.1309 as applicable.

(c) The EFVS design shall be assessed in accordance with the specifications of either CS 23.2510 or CS 25.1309 as applicable.

(d) An aircraft- and system-level functional hazard assessment (FHA) and system safety assessment (SSA) shall be prepared to determine the hazard level associated with the system failure conditions and to determine the minimum required software and hardware design assurance levels (DALs).

(e) Any alleviating flight crew actions that are considered in the EFVS safety analysis shall be validated during testing for incorporation in the AFM.

(f) The flight crew workload shall be assessed in accordance with CS 23.2600 or CS 25.1302 as applicable.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.107 EFVS safety assessment

ED Decision 2022/007/R

The safety assessment should show that the applicant’s specific installation meets all the integrity criteria for the aircraft systems and for the EFVS. All aircraft configurations to be certified should be addressed.

The applicant may need to assess by flight test or simulation the effects of combinations of EFVS malfunctions that are not classified as Catastrophic by the functional hazard analysis (FHA) (to support compliance demonstration to CS 23.2500(a), CS 23.2500(b), CS 23.2510, CS 23.2605 or CS 25.1309, as applicable).

The overall level of safety of the aircraft is based on installed equipment. A complete system safety assessment (SSA) should be conducted. The SSA should consider the potential for hazardously misleading information (HMI) being presented to the flight crew. Examples of HMI that should be considered include at least information providing attitude, altitude, and distance cues as outside terrain imagery, frozen and offset imagery.

EFVS fail-safe features

The normal operation of the EFVS may not adversely affect, or be adversely affected by, other normally operating aircraft systems. Detected malfunctions of the EFVS which could cause display of misleading information should be annunciated and the misleading information removed. The criticality of the EFVS’s function to display imagery, including the potential to display HMI, should be assessed according to CS 25.1309 and AMC 25-11. Likewise, the hazard effects of any malfunction of the EFVS that could adversely affect interfaced equipment or associated systems should be determined and assessed according to CS 25.1309 and AMC 25-11. Similar criteria can be found in CS 23.2510. This requirement should be met through an SSA and documented via fault tree analysis (FTA), failure mode and effects analysis (FMEA), and failure mode and effects analysis substantiation (FMEA substantiation), or equivalent safety documentation.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.108 Enhanced flight vision system (EFVS) level of safety

ED Decision 2022/007/R

(a) The safety design goals for airworthiness approval shall be established and shall consider the phase of flight and include the required:

(1) accuracy,

(2) continuity,

(3) availability, and

(4) integrity.

(b) An FHA shall be conducted in accordance with CS 23.2510 or CS 25.1309 as applicable.

(c) The EFVS safety level (failure and performance) shall not be less than the safety level required for non-EFVS-A-based precision and non-precision approaches (NPAs) with DAs/DHs of 60 m (200 ft) or above.

(d) The ability of the pilot(s) to cope with any failures identified in the SSA or to provide intervention to limit the effect of a hazard shall be demonstrated and justified.

(e) In showing compliance, any probabilities used shall not be factored by the fraction of approaches which are made using EFVS.

(f) For EFVS-L, a satisfactory level of safety (failure and performance) appropriate to the operations being addressed shall be demonstrated with the visual segment primarily accomplished by the use of an EFVS-L rather than natural vision.

(g) For EFVS-L, a system evaluation shall be conducted to establish the failure modes and determine whether the pilot can safely land and roll out with available natural vision plus whatever remains of the EFVS-L. The evaluation shall not assume that a safe landing can be achieved with only available natural vision after any failure of the EFVS-L.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.108 EFVS level of safety

ED Decision 2022/007/R

During the development and design of an EFVS, the safety design goals for airworthiness approval should be established. The safety criteria for each phase of flight, including approach and landing systems, should be defined in terms of accuracy, continuity, availability, and integrity. Appropriate design guidance should be used to determine the overall required level of safety for the aircraft, in any mode of flight, and for any combination of failures which can cause an unsafe condition in order for them to be fully assessed and categorised. This should include the ability of the flight crew to cope with these failures. The hazard level for any aircraft system will depend on the ability of the flight crew to cope with failures. For failures where the SSA assumes a particular pilot intervention to limit the hazard effects (for example, from catastrophic or hazardous to major or minor), it should be shown that the pilot can be relied on to perform that intervention. For example, the pilot might be assumed to detect a system error because of other displays or out-the-window view.

It should be demonstrated that flight crew can detect the error in a timely fashion and not be hazardously misled. The demonstration must validate the hazard classification contained in either CS 23.2510 or CS 25.1309, as appropriate.

The applicant should demonstrate a satisfactory safety (failure and performance) level which should not be lower than the safety level required for precision and NPAs with decision altitudes (DAs) of 200 ft or above without the use of an EFVS. In showing compliance, probabilities cannot be factored by the fraction of approaches which are performed using EFVS. Consideration, however, can be given to the EFVS critical flight time, such as from the highest DH that can be expected for an approach to 100 ft above the TDZE using an EFVS-A.

The selected DALs are directly linked to the specific intended use and to the specific EFVS installation as an integrated part of the flight deck flight information system.

In showing compliance with these safety criteria, the probabilities of failure conditions of an EFVS-L should not be factored by the fraction of approaches which require an EFVS-L. The probabilities of failure conditions of an EFVS-L should also not be factored by a statistical distribution of visibility conditions. The exposure time used for failure calculations of an EFVS-L should be the elapsed time from descent below the highest expected DA/H for the approach using an EFVS-L to completion of roll-out to a safe taxi speed.

Any malfunction, fault detection and annunciation schemes should satisfy the required levels of safety and should perform their intended functions.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.109 Enhanced flight vision system (EFVS) performance

ED Decision 2022/007/R

(a) A performance demonstration and evaluation of the enhanced flight vision system (EFVS) shall be performed, and shall include demonstrations of:

(1) approach,

(2) missed approach,

(3) failure conditions, and

(4) crosswind conditions.

(b) The demonstration of performance shall consider the lateral and vertical limits that could exist at the approach minima for the type of intended approach for which certification is sought.

(c) The performance of the EFVS sensor shall be established in terms of the visual advantage of the system when low-visibility conditions exist. This shall be achieved by determining the ability of the EFVS sensor to provide the display of the visual references of the runway environment that are required at operationally relevant distances (see AMC7 SPA.LVO.105(c) point (e)).

(d) The EFVS sensor resolution performance shall adequately resolve, for pilot identification, the runway threshold and the TDZ to enable the intended function.

(e) The maximum allowable final approach course offset shall be established.

(f) The image/symbology of an EFVS shall provide the visual cues for the pilot to control the approach speed (manual or automatic) up to the point of transition to natural vision without requiring exceptional pilot skill, alerting, strength or excessive workload.

(g) An EFVS with superimposed flight symbology shall not mislead nor distract the pilot, nor jeopardise the safety of the landing and roll-out, and the performance of the system shall be demonstrated to be equivalent to or better than that normally achieved in visual operations for the specific aircraft type for all performance parameters measured.

(h) The HUD (or equivalent display) shall meet the performance and integrity requirements applicable to the intended type of operation. Refer to CS-AWO Subpart B Section 2 SA CAT I, Section 3 CAT II or Section 4 CAT III.

[Issue: CS-AWO/2]

AMC1 AWO.A.EFVS.109 EFVS performance

ED Decision 2022/007/R

The performance of EFVS imaging systems does not solely depend upon system design, but also depends upon the target scene characteristics such as the runway, light structures, electromagnetic radiation, and atmospheric conditions.

Since the purpose of the EFVS sensor is to provide a visual advantage over the pilot’s out-the-window view, the design should include a general performance analysis. This analysis should include the calculated performance, which indicates the viability of the system to meet the proposed intended function, specifically including the calculated performance of the sensor operation within the range of the environment proposed.

Likewise, since the purpose of the EFVS sensor is to provide a visual advantage over the pilot’s out‑the‑window view, the general performance analysis should include the calculated transmission of electromagnetic energy in the visible spectrum and other relevant frequencies. The analysis should portray the length of transmission over a path with generalised extinction coefficients at a given wavelength.

EUROCAE ED-291 Test Procedures for Quantified Visual Advantage Issue 1 contains an acceptable methodology for determining and quantifying the visual advantage for an EFVS-A or EFVS-L, and should be used as the basis for the flight test.

Note: Examples of acceptable sensor models are MODTRAN and LOWTRAN, which can be used to estimate the performance of infrared systems. Other models (FASCODE) for radar systems may be used for these types of sensors and provide a basic measure of signal attenuation helpful in assessing performance and viability for the required functions.

Both the installed system and the individual system components should be verified to ensure compliance with the requirements in Book 1 Subpart A Section 3.

Airframe and equipment manufacturer-based tests or analyses, as applicable, should be developed and conducted to validate the detailed system criteria. No specific test procedures are cited because alternative methods can be used. Alternate procedures can be utilised if it can be demonstrated that they provide the totality of the required information. System performance tests are the most important tests as they relate to operational capability. Subsystem tests are used as subsystems are added during system build-up to ensure appropriate subsystem performance as it relates to overall system performance.

An evaluation of the system used during anticipated operational scenarios should be conducted.

The minimum detection EFVS range can be derived by using an assumed minimum distance of the aircraft at the nominal Category I (200 ft) DA before which the EFVS should image the visual cues required by AMC7 SPA.LVO.105(c) point (e).

Sensor resolution

As a minimum, the EFVS resolution performance shall adequately resolve (for pilot identification) the runway threshold and the TDZ to enable the intended function. For example, an EFVS should resolve a 60-ft wide runway from 200 ft height above the TDZE with a typical 3-degree glideslope. The sensor resolution has been established by providing this resolution at a minimum range, allowing the pilot to continue the descent below DA or MDA. (These values do not take into account pilot decision time or actual atmospheric conditions, or the use of NPAs which may require greater distances.) A 60-ft wide runway has been chosen as the ICAO minimum runway width to support instrument approach procedures.

Display resolution

Since the sensor can be active or passive, the EFVS display should adequately resolve a 60-ft wide runway from 200 ft height above the TDZE with a typical 3-degree glideslope. The pilot needs to be able to detect and accurately identify the visual references in the image.

Performance demonstration

The performance demonstration, establishing aircraft system compliance, typically includes bench testing, flight testing, data collection, and data reduction to show that the proposed performance criteria can be met. Minimal performance standards necessitate an evaluation of the system used during anticipated operational scenarios. The performance evaluations should, therefore, include demonstrations of taxi, take-off, missed approaches, failure conditions, crosswind conditions, and approaches into specific aerodromes as appropriate for the system’s intended function. For EFVSs, performance at the lateral and vertical limits for the type of approach (for example, precision, non‑precision, and approach with vertical guidance) for which operational credit is being sought should be demonstrated.

The applicant should demonstrate compliance through flight test using an aircraft that is fully representative for the purpose of the test in terms of flight deck geometry, instrumentation, alerts, indications, and controls (in the air or on the ground).

In addition, the applicant should use any of these three general verification methods to supplement flight testing:

(a) Analysis: demonstrate compliance using an engineering analysis.

(b) Laboratory test: demonstrate compliance using an engineering bench representative of the final EFVS being certified.

(c) Simulation: demonstrate compliance using a flight simulator.

The individual verification methods that are to be used should be specified in the certification plan to be agreed by EASA. For extensions, features, and design decisions not explicitly specified in this certification specification, human factors evaluations should be conducted through analyses, bench, simulation, or flight testing.

Final approach course offsets greater than 3 degrees should be subject to additional flight test evaluation. The maximum allowable final approach course offset is established by flight testing. This testing should include the factors related to the offset, such as HUD/EFVS FOV, crosswinds, and the maximum drift angle for a conformal FPV.

Benchmark data establishing equivalence to normal visual operations with a specific aircraft should not normally be necessary. However, if flight test results show deviations from the standard criteria listed above, then benchmark data might be used to establish the equivalence of operations with EFVS-L to normal visual operations for that specific aircraft.

The image/symbology of EFVS-L should provide the visual cues for the pilot to perform the following actions without requiring exceptional piloting skill, alerting, strength, or excessive workload:

(a) Speed control within +10/–5 kt of the approach speed, whether manually controlled or with auto-throttle, up to the point where the throttles are retarded for landing.

(b) A smooth transition through flare to landing.

(c) Approach, flare, and landing at a normal sink rate for the aircraft.

(d) All touchdowns in the TDZ. Lateral touchdown performance should be demonstrated to be no worse than that achieved in visual operations with natural vision for a specific aircraft. Longitudinal touchdown performance must be demonstrated within the TDZ which is the first one third, or the first 3 000 ft, of the usable runway, whichever is more restrictive, and demonstrated to be equivalent to or better than that achieved in visual operations with natural vision for that specific aircraft.

(e) Prompt and predictable correction of any lateral deviation away from the runway centre line to smoothly intercept the centre line.

(f) Touchdowns with a bank angle that is not hazardous to the aeroplane.

(g) Demonstrated performance of the installed EFVS at representative visibilities for operations conducted with EFVS-A and EFVS-L, as described in this document, will determine any additional limitation (for example, crosswind and offset).

(h) A normal derotation.

(i) Satisfactory and smooth control of the aeroplane from touchdown to a safe taxi speed.

(j) Satisfactory and smooth control of the path of the aeroplane along the runway centre line through roll-out to a safe taxi speed.

(k) A safe go-around at any time, including up to touchdown in all configurations to be certified.

EFVS-L performance demonstration

For EFVS-Ls and, where appropriate, for the performance demonstration, the non-visual conditions can be achieved either by natural obscuration or by use of a visibility-limiting device in front of the pilot. Caution should be used if the use of a visibility-limiting device for system performance demonstrations is selected. Visibility-limiting devices may not adequately simulate low-visibility conditions for all performance demonstrations of EFVS-Ls because of the unrealistically good external visibility outside the HUD FOV and the unrealistic image performance of the EFVS-Ls in good atmospheric conditions.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.110 Enhanced flight vision system — landing (EFVS‑L) — Landing performance

ED Decision 2022/007/R

(a) The lateral and longitudinal touchdown performance of an EFVS-L system shall be demonstrated and shall be equivalent to or better than that normally achieved in visual operations. The use of the EFVS-L system must provide acceptable performance in all conditions for which it is intended to be used.

(b) If EFVS-L flare cue results in an increase to the landing distance, then the appropriate increment shall be established and scheduled in the AFM.

(c) The image/symbology of an EFVS-L system shall provide the visual cues for the pilot to perform the following without requiring exceptional piloting skill, alerting, strength or excessive workload:

(1) control of approach speed (manual or automatic) up to the point of landing;

(2) transition through flare to landing;

(3) approach, flare, and landing at a normal sink rate for the aircraft;

(4) prompt and predictable correction of any lateral deviation away from the runway centre line to smoothly intercept the centre line;

(5) touchdowns with a bank angle that is not hazardous to the aeroplane;

(6) a normal derotation;

(7) control of the path of the aeroplane along the runway centre line through roll-out to a safe taxi speed; and

(8) a safe go-around any time, including up to touchdown in all configurations to be certified.

[Issue: CS-AWO/2]

AMC1 AWO.A.EFVS.110 EFVS-L landing performance

ED Decision 2022/007/R

(a) Due to the fact that a flare cue is required for EFVS-L operations, the landing distance to be applied for EFVS-L operations should be the landing distance established for the flare cue (see AMC AWO.A.HUD.112).

(b) During all EFVS-L tests, the acceptable landing criteria should be achieved and demonstrated in accordance with the criteria of AMC2 AWO.A.EFVS.110.

[Issue: CS-AWO/2]

AMC2 AWO.A.EFVS.110 Acceptable landing performance criteria for EFVS-Ls

ED Decision 2022/007/R

(a) The landing performance of an EFVS-L is acceptable if the EFVS-L image/symbology provides the pilot with visual cues to enable to perform the following without requiring exceptional piloting skill or alertness:

(1) Speed control within +10/–5 kt of the approach speed, whether manually controlled or with auto-throttle, as proposed by the applicant, up to the point where the throttles are retarded for landing.

(2) A smooth transition through flare to landing.

(3) Approach, flare, and landing at a normal sink rate for the aircraft, i.e. the average touchdown rate of descent not exceeding 6 ft per second.

(4) All touchdowns in the TDZ. Longitudinal touchdown performance should be demonstrated within the TDZ which is the first one third, or the first 3 000 ft, of the usable runway, whichever is more restrictive, and demonstrated to be equivalent to or better than that achieved in visual operations for the specific aircraft.

(5) Prompt and predictable correction of any lateral deviation away from the runway centre line to smoothly intercept the centre line.

(6) Touchdowns with a bank angle that is not hazardous to the aeroplane, i.e. no contact of any part of the engine nacelle or the wing with the ground.

(7) A normal derotation.

(8) Satisfactory and smooth control of the aeroplane from touchdown to a safe taxi speed.

(9) Satisfactory and smooth control of the path of the aeroplane along the runway centre line through roll-out to a safe taxi speed.

(10) A safe go-around any time, including up to touchdown in all configurations to be certified.

(b) The demonstrated performance of the installed EFVS-L at representative visibility levels for EFVS landing system operations will determine whether there is a need for any additional limitations (for example, crosswind and offset). Appropriate limitations should be published in the AFM.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.111 Enhanced flight visual system (EFVS) monitoring, annunciation and alerting

ED Decision 2022/007/R

(a) The mode of operation (display status (e.g. displayed/not displayed)) and any mode that could have an impact on the EFVS performance (e.g. level of contrast or resolution of the image) shall be:

(1) annunciated on the flight deck;

(2) visible to the flight crew; and

(3) recorded by the flight data recorder if required to be installed.

(b) Any detected EFVS malfunction that can adversely affect the normal operation of the EFVS shall be annunciated to the flight crew and shall include as a minimum sensor failures and frozen image failure messages.

(c) No single EFVS malfunction shall lead to the display of misleading information leading to a Hazardous or Catastrophic failure condition. Detected malfunctions shall be annunciated and the malfunctioning display elements removed.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.111 EFVS monitoring, annunciation and alerting

ED Decision 2022/007/R

Failure messages

EFVS malfunctions detected by the system, and which can adversely affect the normal operation of the EFVS, should be annunciated. As a minimum, specific in-flight failure message(s) for sensor failure and frozen image should be displayed to the flight crew.

EFVS annunciations

Any modes of EFVS operation should be annunciated on the flight deck and should be visible to the flight crew. The modes of the EFVS operation should be made available to the flight data recorder, as required.

[Issue: CS-AWO/2]

CS AWO.A.EFVS.112 Enhanced flight vision system (EFVS) documentation

ED Decision 2022/007/R

The demonstrated capability and any specific EFVS limitations shall be included within the relevant AFM section.

[Issue: CS-AWO/2]

AMC AWO.A.EFVS.112 EFVS documentation

ED Decision 2022/007/R

The following minimum information should be provided in the AFM:

(a) the approved limits established as a result of consideration of any other factor that the certification has shown to be appropriate;

(b) the normal and abnormal procedures, including airspeeds;

(c) the minimum required equipment;

(d) any additional aeroplane performance limitations;

(e) if appropriate, the type of approaches and the xLS navigation means (facilities external to the aircraft) and associated limitations (if any) which have been used as the basis for certification;

(f) any related limitations and/or assumptions on the runway or aerodrome conditions that are affected by the use of the EFVS; for EFVS-L, this should also consider:

(1) runway elevation,

(2) approach path slope,

(3) touchdown zone slope,

(4) ground profile under the approach path;

(g) the type and mode of operation/configuration of the approach lights (i.e. LED or incandescent) that have been used or assumed during the certification demonstration of the EFVS;

(h) the demonstrated performance in accordance with CS AWO.A.EFVS.109;

(i) wind speed limitations that are affected by the use of the EFVS;

(j) any applicable assumptions that have been made during the certification demonstration of the EFVS.

[Issue: CS-AWO/2]

Appendix 1 to the AMC to Section 3 of Subpart A

ED Decision 2022/007/R

EFVS compliance

The following is a non-exhaustive list of certification specification in CS-25 that could be affected by an EFVS installation.

Applicants for normal-category aeroplanes (CS-23) can use the list below to establish whether the equivalent aspects in CS-23 are affected and address them accordingly.

Note: As of Amendment 5 to CS-23, the referenced CS-23 requirement numbers are reflected in the AMC to CS-23.

[Issue: CS-AWO/2]