Created Thursday, Aug 25th 2022 17:55Z, last updated Thursday, Aug 25th 2022 17:55Z
A Hop! Canadair CRJ-700 on behalf of Air France, registration F-GRZL performing flight
AF-1551 from Lille to Lyon (France), was on approach to Lyon, low visibility procedures were in effect, and was cleared for an ILS Cat III approach to runway 35R. During the final approach at about 07:50L (06:50Z) the aircraft however veered to the left, the aircraft initiated a go around and overflew the threshold of runway 35L (instead of assigned runway 35R). The aircraft positioned for another approach and landed without further incident.
The French BEA rated the occurrence a serious incident and opened an investigation.
On Aug 25th 2022 the BEA released their final report in French only (Editorial note: the English version is to be expected in due time, analysis will be included then) concluding the probable causes of the incident were:
These factors may have contributed to the approach being performed in a mode other than AIII:
- Inadequate use of the control panel by the crew, which may have resulted in:
+ either an erroneous selection of the piloting mode from the control panel at the beginning of the descent or an erroneous selection of the piloting mode from the control panel at the beginning of the descent,
+ or a deselection of the AIII mode linked to the execution of the RA test after having prearmed mode AIII,
- the fact that the conditions for arming the AIII mode were not met, which would have meant that this mode, even if correctly selected, did not arm;
- an inadequate verification of the parameters of the approach on the PFD and the HUD, approach parameters on the PFDs and the HUD, in particular during the calls foreseen by the standard procedures, which did not allow the crew to detect that the AIII mode was not the active mode.
The following may have contributed to the trajectory deviations and the destabilization of the approach:
- repeated corrections of increasing amplitude when following the indicated trajectory by the CDB, in a context of execution of its first ILS CAT IIIa approach at HGS. ILS CAT IIIa approach on the HUD without visibility in flight;
- the CDB's attention on the HUD symbols for the alignment of the "Flight path symbol" with the "Guidance path symbol with the guidance cue to the detriment of following the LOC LOC deviation indication;
- partial monitoring of the trajectory on short final by the co-pilot, whose attention was diverted to correct a radio problem on his headset.
Although in-service malfunctions of this type are very rare, it was not possible to exclude the possibility of an erratic behavior of the HGS flight director during the approach.
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