Excessive taxiing speed and disregard for standard procedures caused an Air Berlin Boeing 737-800 (D-ABKA) to slide off the runway during line-up in snowy conditions at Nuremberg airport in January 2010.
German air accident investigation bureau BFU determined that the pilots attempted a rolling take-off even though the manufacturer's manual did not permit such manoeuvres in the prevailing subzero temperatures.
None of the 125 passengers and six crew members was injured during the serious incident, but the aircraft sustained minor damage.
During taxi, the tower had instructed the pilots to line up on runway 10 and, seconds later, issued take-off clearance.
When the aircraft entered the runway at 12kt (22km/h) ground speed, it needed to make an 80° right turn. But Air Berlin's operating manual mandates pilots to make turns greater than 75° at a maximum speed of 10kt.
The surface was covered with a thin layer of snow, and the pilots had been informed of "medium" braking action. While turning onto the runway, the pilot advanced the throttles to around 43% N1 even though Boeing stipulates to do so only once lined up.
The accelerating aircraft crossed the runway centreline with both main landing-gear, with the pilot trying to return to the middle by steering the nose wheel right. This caused the 737 to veer to a maximum 120° heading, travelling at up to 19kt.
The pilot then tried to steer to the left but the aircraft no longer responded. He reduced the throttle to idle and the aircraft came to a stop 150m (490ft) from the runway threshold, with the nose and right main wheels sunk into the ground.
BFU concluded that "due to the recorded speeds and early thrust increase on the snow-covered ground, the crew had to anticipate that the aircraft could potentially slide".
Source: Air Transport Intelligence news
