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| Date: | Monday 4 October 1999 |
| Time: | 06:15 |
| Type: |  British Aerospace BAe-146-300 |
| Owner/operator: | KLM UK |
| Registration: | G-UKID |
| MSN: | E3157 |
| Fatalities: | Fatalities: 0 / Occupants: 99 |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Location: | Over England -
 United Kingdom
|
| Phase: | Initial climb |
| Nature: | Passenger - Scheduled |
| Departure airport: | Aberdeen International Airport (ABZ/EGPD) |
| Amsterdam-Schiphol Airport (AMS/EHAM) | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The aircraft had been parked for several hours overnight on stands 4/5 at Aberdeen Airport, under
cloudy skies with light rain showers and a surface temperature no lower than +7°C, ready for an
early morning scheduled departure for Amsterdam. The automatic terminal information system
(ATIS) timed at 0520 hrs, gave Runway 34 in use, surface wind 320°/14 kt, visibility 15 km with
few clouds at 1,200 feet, few cumulonimbus (CB) at 1,800 feet, scattered at 2,300 feet with a
temperature of +7°C, a dewpoint of +5°C and a QNH of 1009mb. The aircraft taxied from its stand
at 0523 hrs. The crew completed the normal checks prior to departure and carried out a 'full and
free' controls check prior to their take off at 0533 hrs.
An aircraft Technical Log entry referred to an autopilot fault known to be apparent on autopilot
engagement, but the autopilot had not been rendered unserviceable. The commander, who was the
pilot flying (PF), initially flew the aircraft manually. However, during the climb at approximately
FL100 to FL110 the commander decided to engage the autopilot to assess whether it would operate
normally. On engagement of the autopilot, however, the aircraft pitched markedly nose down and
rolled to the left. He therefore disengaged the autopilot immediately and continued the climb. As
the aircraft continued its climb towards FL 250, the commander reported that the ailerons had
become stiffer to operate and eventually 'locked solid'. The first officer tried his controls but they
were also similarly affected. The aircraft was levelled at FL270 and because it had been climbing in
a wings level attitude, the commander decided not to apply excessive force to overcome the aileron
jam, as would have been the case if he had adhered to the 'AILERON JAM OR
UNCOMMANDED ROLL' drill; the aircraft was therefore manoeuvred laterally using aileron trim.
The commander reasoned that to overcome any restriction could induce a sudden and violent rate
of roll which might become difficult to control. Lateral control of the aircraft using the aileron trim
alone appeared satisfactory and after getting used to the different roll response, the commander was
able to maintain the desired heading.
The crew suspected that water from overnight rain had entered the control runs and frozen. The
aircraft was overweight for a landing at Edinburgh or Newcastle, and gusty crosswinds and
thunderstorms were forecast at their planned destination. The crew therefore declared a PAN and
requested a diversion to Stansted where the weather was better. The commander subsequently
requested a descent to 5,000 feet, the height of the freezing level, in the hope that the aileron
controls would become free. The restriction however remained as the aircraft approached this level.
The commander then operated the manual aileron disconnect handle, expecting the jam to clear but
this had no effect. However, as the aircraft descended further to 2,500 feet, the ailerons gradually
became free and, after a slow speed handling check carried out at 3,000 feet with the landing gear
down and 24° of flap selected, the crew made an uneventful landing at Stansted from a long
straight-in approach.
Accident investigation:
 |
|
Sources:
https://assets.publishing.service.gov.uk/media/5422f53940f0b613460005b7/dft_avsafety_pdf_501083.pdf
https://www.jetphotos.com/photo/10592802 (Photo)
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 04-Apr-2025 07:31 | Justanormalperson | Added |
| 04-Apr-2025 07:32 | ASN | Updated [Accident report, ] |
Corrections or additions? ... Edit this accident description
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