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| Title: | Control problems in icing, Serious incident occurring 14 December 1998, 15 km westlich Cottbus, to Aerospatiale-Alenia/ATR 42-300 |
| Micro summary: | This ATR 42-300 experienced flight control difficulties in icing conditions. |
| Event Time: | 1998-12-14 at 1109 UTC |
| File Name: | 1998-12-14-DE.pdf |
| Publishing Agency: | Federal Bureau of Aircraft Accidents Investigation (BFU) |
| Publishing Country: | Germany |
| Report number: | 5X011-0/98 |
| Pages: | 12 |
| Diversion Airport: | Berlin-Schönefeld Airport, Berlin, Germany |
| Site of event: | Climb from Desden. |
| Departure: | Dresden Klotzsche Airport, Dresden, Germany |
| Destination: | Poznan-Lawiza Airport, Poznan, Poland |
| Airplane Type(s): | ATR 42-300 |
| Flight Phase: | Climb |
| Registration(s): | Unknown |
| Operator(s): | Unknown |
| Type of flight: | Revenue |
| Occupants: | Unknown |
| Fatalities: | 0 |
| Serious Injuries: | 0 |
| Minor/Non-Injured: | Unknown |
| Other Injuries: | 0 |
| Diverted to: | Berlin-Schönefeld Airport, Berlin, Germany |
| Executive Summary: | The aircraft had departed at 11:09 UTC from Dresden to Posen (Poland). The temperature at the aerodrome of departure was +5°C (ATIS L 10:50 UTC). The first officer was the pilot flying (PF). During climb the aircraft entered the clouds at 2000 ft. At 3400 ft the autopilot (AP) was connected. The crew had preselected the climb out speed to 160 kt. The crew established light aircraft icing approx. from flight level (FL) 80 and moderate aircraft icing from FL 120. The anti-icing equipment as well as the airframe de-icing equipment were switched on at stage III. A visual check indicated to the crew that the deicer boots on the wings were functioning normally and had no ice accretion. On the unheated portion of the forward side windows of the cockpit rime ice was visible. During climb the PF pushed the touch control steering button several times in order to check the control surfaces for smooth operation. The climb rate decreased to approx. 500 ft/min. Thus the crew reduced the climb out speed by 5 kt to 155 kt, in order to maintain the climb rate and in the hope of being able to leave the clouds towards the tops. Approx. at FL 135 the climb rate, however, was only 200 to 300 ft/min (Attachment 1 shows the development of the climb rate with time). Due to this fact the crew decided to interrupt the climb to the planned flight level of FL 190 in order to make the airspeed increase again. For this purpose they activated the Altitude Hold Mode (ALT HOLD Mode). After a light increase to approx. 160 kt the airspeed again dropped to the initial value. Shortly afterwards at a speed of 155 kt the stall warning was activated suddenly and ‘quite unexpectedly’ for the crew and the AP was switched off automatically. The aircraft immediately banked heavily to the left and afterwards to the right. Now the bank attitude changed several times from left to right. The PF counteracted the bank attitude with full aileron deflections. The aircraft assumed an uncontrolled flight attitude. After the crew had regained control of the aircraft the pilot-in-command (PIC) declared an in-flight emergency to the responsible air traffic control unit and at 11:49 UTC performed a precautionary landing to Berlin-Schönefeld aerodrome without any problems. Conclusions The incident was caused by the fact that the crew lost the control of the aircraft after the aircraft entered and continued operation in severe icing conditions for which the aircraft is not certificated. The crew had failed to associate icing of the forward side windows with the severe icing phenomenon. |
| Learning Keywords: | Operations - Icing |
| Other - Certification |
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