Unintended Trim Movement During Landing at Paris Charles de Gaulle

Casualties unknown • Paris Charles de Gaulle, FR

An AIRJET crew experienced significant pitch-up tendencies during the final approach of a BAe 146, caused by an unintended movement of the elevator trim.

What happened

On August 23, 1998, a BAe 146-200 QC, registration F-GOMA, was performing a technical flight from Brussels to Paris Charles de Gaulle. During the pre-flight checks at the parking stand in Brussels, the co-pilot noted that the elevator trim was at its full nose-up limit and manually reset it to neutral. The flight proceeded normally until the aircraft reached approximately 6,000 feet, at which point the autopilot was disconnected for manual approach.

As the aircraft descended to 200 feet on final approach, the pilot in command experienced a sudden, heavy nose-up force on the control column. The pilot had to physically push the yoke forward and requested the assistance of the co-pilot to maintain the descent path and execute the flare. Upon touchdown, the nose-up tendency persisted, causing the aircraft to bounce slightly before the pilot stabilized the landing. Following the landing, the crew discovered that the elevator trim had moved back to its full nose-up position.

The investigation

The investigation focused on the electrical trim chain, including the autopilot computer, the autopilot control and engage unit, and the servo actuator. These components were examined at the manufacturer's facility in the United Kingdom. Investigators also inspected the electric trim switches located on the control column and verified the aircraft's electrical wiring.

Flight parameter recorder data revealed that the trim movement occurred at a rate of approximately 1.1 degrees per second, which corresponds to the speed of the electric trim mode rather than the slower autopilot trim mode. This indicated that the movement was triggered by the electric trim switches rather than the autopilot computer.

Findings

  • The investigation found no mechanical or electrical failures within the trim chain components or the aircraft wiring.
  • The speed of the trim movement confirmed that the electric trim system was active, rather than the autopilot's automatic trim mode.
  • The aircraft lacked a "whooler" alarm, which would have alerted the crew to the trim movement.
  • The crew's attention was focused on the runway during the final stages of the approach, and they did not perceive the trim wheel moving.
  • The investigation concluded that the movement was the result of an involuntary action by the pilot on the electric trim switches during the landing phase.

Probable cause

The incident was caused by the aircraft being in an out-of-trim configuration during final approach, resulting from the pilot's unintentional activation of the electric trim switches during the flare.

Frequently asked questions

What happened in the 1998-08-23 MINISTERE DE L'EQUIPEMENT DES TRANSPORTS ET DU LOGEMENT - INSPECTION GENERALE DE L'AVIATION CIVILE ET DE LA METEOROLOGIE - FRANCE Incident survenu le 23 août 1998 à Paris Charles de Gaulle accident near Paris Charles de Gaulle, FR?

An AIRJET crew experienced significant pitch-up tendencies during the final approach of a BAe 146, caused by an unintended movement of the elevator trim.

What aircraft was involved and where did it happen?

The accident on 1998-08-23 involved a MINISTERE DE L'EQUIPEMENT DES TRANSPORTS ET DU LOGEMENT - INSPECTION GENERALE DE L'AVIATION CIVILE ET DE LA METEOROLOGIE - FRANCE Incident survenu le 23 août 1998 à Paris Charles de Gaulle, at Paris Charles de Gaulle, FR.

What was the probable cause of the accident?

The incident was caused by the aircraft being in an out-of-trim configuration during final approach, resulting from the pilot's unintentional activation of the electric trim switches during the flare.

Loading the flight search…