History of the Flight
On Monday 23 May 2022, a Beechcraft C90A King Air, registered F-HHAM, was on an instrument flight rules (IFR) flight from Ancenis aerodrome to Paris-Le Bourget airport. The pilot and one passenger were on board. While being radar-vectored in the Paris-Charles de Gaulle (CDG) approach sector, the pilot was instructed to turn left to a heading of 300° and cleared for an ILS approach to runway 27 at Le Bourget. Shortly before intercepting the centreline, the aircraft stopped following the selected heading and turned right, crossing the centreline on a northerly path. The controller immediately instructed the pilot to turn left to a heading of 180°, and an Airbus A320 on approach to CDG was directed to turn right. The pilot of F-HHAM read back the instruction and turned left, but during the maneuver lost control, descending approximately 3,000 ft in 15 seconds. The pilot regained control, reported a problem with the artificial horizon, and climbed back to 5,000 ft. During the loss of control, the aircraft came close to a second Airbus A320 on approach to runway 26L at CDG, initially 1,000 ft below. The minimum separation was estimated at 0.6 NM and 125 ft, triggering a short-term conflict alert (STCA). The pilot later continued the approach using right-side instruments and landed without further difficulty.
Pilot Information
The 59-year-old pilot held a Commercial Pilot Licence with approximately 11,000 flight hours, a BE90 rating, and examiner authorizations. He reported considerable experience on Beechcraft 90s and had flown F-HHAM several times without technical issues. On the day of the incident, he had flown earlier flights to Montpellier and Ancenis. During the approach, he was flying in cloud and had no memory from when he was established on heading 300° until after the loss of control. He described it as if he was "sleeping." He recalled seeing an unusual indication on his Electronic Attitude Director Indicator (EADI) and then noticing a steep bank angle on the right-side artificial horizon. After regaining control, he observed a discrepancy between left and right horizon indications, which later became consistent shortly before landing. Following the incident, he consulted a physician and underwent medical examinations that revealed no contributing elements.
Medical Factors
The BEA report discusses medical fitness versus capability. In the absence of a medical explanation for the incapacitation, lifestyle and dietary factors are considered. Given the pilot's early wake-up time and lack of a full lunch, hypoglycemia may have resulted in subtle incapacitation. Additionally, a recently altered sleep pattern could have led to cognitive impairments or hypovigilance, potentially explaining the pilot's memory loss and inappropriate reactions.
Tests and Research
Ground tests on the attitude acquisition system and autopilot (AP) were conducted per the maintenance manual. The heading display on the Electronic Horizontal Situation Indicator (EHSI) was correct, the flux valve slaving system functional, and the AP performed as expected during all tests, including ILS approach simulations. A subsequent check flight with a BEA investigator showed nominal operation of AP and avionics, including an ILS approach to runway 27 at Le Bourget.
Similar Incident
On 2 November 2022, the BEA was notified of a similar incident involving F-HHAM during an approach to Le Bourget, where the pilot had difficulty intercepting the approach path, crossing it multiple times without managing to stabilize.
Conclusion
The incident involved a subtle incapacitation of the pilot during the approach phase, leading to a path deviation, temporary loss of control, and a close proximity event with another aircraft. No injuries or damage occurred.