Synopsis

On 12 March 2005, a BAe-146-300 climbing out of Frankfurt experienced a loss of elevator control authority and an uncommanded descent at up to 4500 fpm whilst in a nose high pitch attde which was eventually arrested and subsequently attributed to the freezing of re-hydrated ground de/anti-ice fluid residues. The crew decided to continue to their originally-intended destination since it offered the prospect of more favourable weather conditions for landing. The aircraft later landed at Stuttgart after using elevator trim to control pitch attitude.

Description

The following extract is from the official BFU Germany report on the Serious Incident:

"The airplane experienced a slow pitch oscillation with increasing amplitude during climb from flight level (FL) 80 to FL100 with engaged autopilot. […] The oscillation resulted in a positive angle of attack of up to 18 degrees and in a rate of descent of up to 4,500 ft/min.

The crew regained control of the airplane in instrument meteorological conditions (IMC) and under icing conditions with disengaged autopilot and the help of the manual elevator trim. A prolonged flight in FL130 under visual meteorological conditions (VMC) and free of icing conditions did not change the control problems they experienced with the airplane.

Since the checklists for abnormal and emergency situations did not contain any solution to the existing problem the crew opted for an ILS approach to Stuttgart Airport because of the better weather situation. To control altitude and touchdown the manual elevator trim was used."