BEA - Office of Investigations and Analysis for Civil Aviation Safety of the French Republic

01/12/2023 | Press release | Distributed by Public on 01/12/2023 02:54

Incident to the Bombardier CL600 registered F-GRZL operated by Hop! on 23/01/2020 at Lyon

Incident to the Bombardier CL600 registered F-GRZL operated by Hop! on 23/01/2020 at Lyon

Investigation progression Closed
Progress: 100%

On the day of the incident, LVP procedures were in force at Lyon-Saint-Exupéry airport due to the presence of freezing fog down to the ground. In this context, the crew of F-GRZL performed an ILS CAT IIIa approach for runway 35R. It is mandatory for the captain to use the HUD for this type of approach in CRJ700s.

Standard procedures on the CRJ700 require the crew to set the HGS parameters before the descent. It is specified that the AIII mode must be set to standby when carrying out a manual ILS CAT IIIa approach. The investigation showed that a different mode was very probably active during the approach, without it being possible to determine the precise cause for this. The use of a mode other than AIII did not necessarily degrade the quality of the guidance, but deprived the crew of important information for conducting a CAT IIIa approach (in particular the Approach warning in case of deviation and the display of the runway edge lines).

At a height of about 500 ft, as the aeroplane, stabilized on ILS 35R, entered the cloud layer, the captain noted that the HGS flight director was indicating lateral guidance orders to the left. The investigation could not determine why the flight director would have indicated "make a left turn" when the aeroplane was stable on the approach path and the localizer signal received by the aircraft was correct.

The captain entered a left turn, probably without identifying the LOC deviation. The aeroplane then deviated from the runway centreline. The captain started making a nose-up input that lasted about 30 s, resulting in the aeroplane passing above the glide path.

The co-pilot was busy resolving a radio reception problem on his headset. When he resumed his monitoring of the PFD parameters, he noticed deviations and called them out to the captain. The captain told the co-pilot that he was correcting them.

The wings were levelled off but the aeroplane continued to diverge by 20° from the runway centreline. Observing on the PFD that the deviations were increasing, the co-pilot suggested to the captain that he go around.

The slow and progressive manner of flying the missed approach, which did not follow the conventional dynamic of a go-around, contributed to the aeroplane losing height and ending up at a speed 15 kt below the reference speed. The slow and progressive manner of flying the missed approach can be explained by:

  • The crew's hesitation for a time on short final, linked to the captain focusing his attention on the HUD symbols to align the Flight path symbol on the Guidance cue, and to the co-pilot's late resumption of the monitoring of the approach, and
  • The absence of the Approach warning message due to the use of an HGS mode which was not the AIII mode, although the conditions for its activation were met. The crews are used to starting a go-around as soon as this message appears.

The aircraft then flew over the airfield buildings at an unusually low altitude, but high enough to avoid any risk of collision with obstacles.

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Deviations from flight path on short final, missed approach, flight over airport buildings, in LVP conditions

General information
Local date 23/01/2020
Responsible entity France - BEA
Scope of Investigation Full (Annex 13) type investigation
State or area of occurrence Europe and North Atlantic - France - 69 Rhône
Location AD Lyon Saint Exupéry
Human consequences None
Aircraft consequences None
Occurrence class Incident
Occurence category NAV: Navigation error
File number BEA2020-0035
Flight Information
Aircraft category Fixed Wing - Aeroplane - Large Aeroplane - Large Aeroplane
Operator France - HOP!
Manufacturer / Model BOMBARDIER - CL600 2C10
Aircraft Registration F-GRZL
State of registry France
Last departure point France - LFQQ (LIL): Lille Lesquin
Planned destination France - LFLL (LYS): Lyon Saint Exupéry
Flight phase Approach
Serial number 10245
Operator Type AG Other
Operation Type Commercial Air Transport - Passenger - Airline

BEA is the French air safety investigation authority for civil aviation. The sole objective of the investigation is to improve air safety. It is intended neither to apportion blame nor to assess responsiblity.