What happened
On May 23, 2022, a Beechcraft C90A King Air, registered F-HHAM, was conducting an IFR flight from Ancenis to Paris-Le Bourget. While on approach to Le Bourget, the aircraft deviated from its assigned heading, crossing the localizer centerline on a path toward the north.
Air traffic controllers immediately intervened, ordering the pilot to turn onto a heading of 180° and instructing the crew of an Airbus A3/20 at nearby Paris-Charles de Gaulle (CDG) airport to turn away to avoid a conflict. During the execution of this maneuver, the pilot lost control of the Beechcraft C90A, resulting in a rapid descent of approximately 3,000 feet in just 15 seconds.
This uncontrolled descent brought the aircraft into close proximity with a second Airbus A320 approaching runway 26L at CDG. The separation between the two aircraft was estimated at only 125 feet vertically and 0.6 nautical miles horizontally, triggering both TCAS resolution advisories for the airliner and a conflict alert in the air traffic control system. The pilot eventually regained control and completed the landing at Le Bourget manually.
The investigation
The BEA examined flight recorder data, radar tracks, and radio communications. The investigation also reviewed the pilot's medical history and the aircraft's avionics systems. Investigators performed ground tests on the autopilot and attitude acquisition systems, including simulations of ILS path acquisition, but found no technical anomalies. A check flight with a BEA investigator also confirmed the avionics were functioning normally.
Regarding the pilot, the investigation noted that the pilot had no memory of the period between the heading deviation and the loss of control, describing a sensation of being as if he were "sleeping." Medical examinations conducted by the pilot following the event did not reveal any underlying chronic health issues.
Findings
- The primary cause of the path deviation and subsequent loss of control was likely subtle pilot incapacitation, potentially triggered by hypoglycaemia due to inadequate food intake and a disrupted sleep pattern.
- The pilot's lack of situational awareness and inappropriate control inputs were exacerbated by physiological factors related to fatigue and nutrition.
- Discrepancies in instrument indications between the left and right sides of the cockpit were reported by the pilot, though these could not be replicated during technical testing.