EFVS certification aspects for operational credit

1. EFVS certification aspectsfor operational credit C.J.A.A Amsterdam November 3rd, 2006 Marc JULIÉ

2. 1 2 3 4 5 6 7 8 Presentation plan • Operations below minimums • EFVS+FD vs CAT 2 system • EFVS CAT1 FD • EFVS FMS LNAV-VNAV • CS 25-1309 aspects • Human factors aspects • Obstacle clearance • Items to be discussed Marc JULIÉ

3. 1 2 3 4 5 6 7 8 assumptions The presentation will focus on aspects specific to: • Operations below CAT1 minimums (down to 100 ft) on CAT1 ILS • Operations below minimums (down to 250 ft) on CDFPA approaches executed with FMS LNAV and VNAV guidance target certification is for a HUD CAT1 flight director system aided by (and superimposed to) a HUD conformal EVS image Marc JULIÉ

4. ops belowminimums EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV CS 25-1309 HF aspects Obstacle clearance t.b. discussed • IFR procedures are based on NAVAIDS-defined or RNAV defined trajectories • EVS image can not be considered as a mean to follow an IFR trajectory, as opposed to a HUD+FD CAT2 system • EVS image provides: • A mean to monitor and check A/C position relative to the runway extended centerline and the glide path. Again, no one can fly the IFR approach trajectory with that • An infrared vision of the outside scenery, thereby it enhances flight visibility • Basically EVS image is a support tool, not a guidance tool • It is an intuitive and low cost (for mental resources) tool to monitor the execution of an approach procedure. Marc JULIÉ

5. EFVS+FD vs CAT 2 Ops below minimums EFVSLNAV-VNAV CS 25-1309 HF aspects Obstacle clearance T.b discussed EFVS CAT1 • In the AFCS CAT2, the pilot actively monitors the flight director / auto-pilot which keeps the airplane on the localizer and the glide slope down to a 100 ft height above touchdown zone, height at which it is required to be capable of visually identifying the runway, by the means of either the runway lighting system or the runway markings or the runway surface itself. • prior to 100 ft, say at 200 ft, horizontal visibility on a CAT2 approach might be only 300m / 1000 ft. On a 5% glide slope, there is no chance that the pilot may see the runway, in the most favourable case may he see the ALS, well below the aeroplane and anyway not in his natural line of sight direction, typically 3 degrees below the horizon. • HUD flight director augmented with EVS will enable the pilot to have EVS visual contact on the runway as soon as 200 ft (otherwise the approach must be discontinued). Between 200 ft and 100 ft, the EVS visual, when still available (otherwise the approach must be discontinued), will allow much safer monitoring of the deviations by comparison with the EVS image: • key point from a safety analysis standpoint, the EVS sensor is totally independent from ILS raw data whereas in the case of CAT2 approaches (AFCS or HUD) the excessive deviations are still based on the ILS raw data, like the flight director Marc JULIÉ

6. EFVS+FD vs CAT 2 Ops below minimums EFVSLNAV-VNAV CS 25-1309 HF aspects Obstacle clearance T.b discussed EFVS CAT1 • the following mitigating factors makes the HUD + EVS a technical solution suitable for operations below 200 ft: • existence of two totally independent means to conduct and monitor the approach • HUD+EVS enables the pilot to be in a situation where at 200 ft, he has a visual (enhanced) contact on the runway, (including the touchdown zone for enhanced RVR 750m) which is not the case in CAT2 operations • The only guidance cue remains the flight director Marc JULIÉ

7. EFVS CAT1 Ops below minimums EFVSLNAV-VNAV CS 25-1309 HF aspects Obstacle clearance T.b discussed EFVS+FD vs CAT2 • flight director performance between 200 ft and 100 ft • flight director control laws between 200ft and 100 ft are the same and the performance as well. • Integrity between 200 ft and 100 ft • below 200 ft, the EVS image will provide integrity monitoring. • This monitoring is double: • First, by supplying an independent image of the outside world, the EVS will make it obvious to the pilot whether the aeroplane is on the runway extended centreline and glide path or not. From this perspective, the intended use of EVS image is a monitoring of flight director guidance. • Second, the monitoring of the EVS image itself is carried out by the pilot watching it, as we will see in CS 25-1309 slide. Marc JULIÉ

8. EFVSLNAV-VNAV EFVS+FD vs CAT2 EFVS CAT1 CS 25-1309 HF aspects Obstacle clearance T.b discussed Ops below minimums • Two main differences with CAT1- EVS: • the precision of the FMS VNAV flight director guidance which triggers the need for some specific features (e.g. cold temperature compensation) • flight time between procedure decision altitude/height and 250 ft might be more important than flight time between procedure decision altitude / height and 100 ft on CAT1-EVS approaches Marc JULIÉ

9. CS 25-1309 EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV HF aspects Obstacle clearance T.b discussed Ops below minimums • Need to adress “display of misleading EVS image” • Misleading EVS image and misleading flight director guidance are very different things • The set reference symbol / flight director guidance cue (e.g. flight path vector / flight path director guidance) is a rather “poor” symbology. The only thing the pilot has to do is to steer the airplane so as to put the reference symbol into the flight director guidance cue. And in case the guidance cue is misleading, the defences of the pilot are limited to the existence of the raw data & deviations and the excessive deviations symbols if any (CAT2 and CAT3 systems only). Also the basic scanning of primary elements (attitude, airspeed, altitude, and heading) is required to determine the misleading FD condition. • EVS image is a much more rich and intuitive symbology Marc JULIÉ

10. CS 25-1309 EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV HF aspects Obstacle clearance T.b discussed Ops below minimums • EVS image is a much more rich and intuitive symbology • even if the aeroplane is on the perfect trajectory, the image will carry on moving and the motion will be all the more perceptible as the aeroplane is close to the touchdown zone, i.e. at a low height. As opposed to this, the flight director does not move any more when perfectly aligned with the reference symbol. Therefore, it is much more difficult for the pilot to detect a frozen flight director than to detect a frozen EVS image, particularly at low altitude. • Secondly, the only point which will be fix in the EVS image in normal conditions (like in any depiction of the outside world) is the main point of interest for the pilot: the flight path termination point, which is precisely the point that must be superimposed with the touchdown point (at least prior to initiating the flare). • In the case of CAT2 approach systems, it is required to demonstrate the safety impact of an AFCS slowover at low height. The slow over detection mean in this case is pilot recognition time of the failure. • It is not considered adequate to make comparison with AFCS CAT2 certification since EVS approaches will not make use of the auto-pilot. Also, in the case of a CAT1+EVS system, trying to demonstrate a similar case would result in considering a simultaneous misleading CAT1 flight director combined with a misleading EVS image which probability is extremely remote. Marc JULIÉ

11. HF aspects EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV CS 25-1309 Obstacle clearance T.b discussed Ops below minimums • EVS impact on pilot's ability to assess the glide path • Mainly due to the absence of natural lateral reference for the horizon whereas the horizon is clearly visible in the HUD FOV due to the EVS • brain’s capacity to “erase” one of the components of the image (between EVS image and HUD conventional symbology) Marc JULIÉ

12. Obstacle clearance EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV CS 25-1309 HF aspects T.b discussed Ops below minimums • Go around, missed approach and OCH (see comments from EASA). • EVS for detecting obstacles such as power lines/wires and pylons, antennas • At G/A pitch attitude is such that there is limited chance that the EVS terrain will be visible in the HUD so can not be considered as a mean on which to rely. Marc JULIÉ

13. T.b discussed EFVS+FD vs CAT2 EFVS CAT1 EFVSLNAV-VNAV CS 25-1309 HF aspects Obstacle clearance Ops below minimums • Cold soak operations • Thermal crossover • Use of barometric or radio altitude references Marc JULIÉ