All four engines failed leaving only critical systems on backup electrical power. One report assigns the engine shutdown to the turning of the ash into a glass coating inside the engines that fooled the engine temperature sensors and led to an auto-shutdown of all four engines.
When all four main generators shut off due to the failure of all the engines, a momentary power interruption occurs when the flight instruments transfer to standby power. Standby power on the 747-400 is provided by two batteries and inverters. The captain performed the engine restart procedure which was not successful on the first few attempts and was repeated until restart was achieved. On some of the attempts, as one or more (but not all) engines started to operate, the main generator would switch back on. This switching on and off caused repeated power transfer interruptions to the flight instruments. The temporary blanking of the instruments gave the appearance that standby power had failed. These power transfers were later verified from the flight data recorder.
After descending more than 14,000 feet, Captain Karl van der Elst and crew were finally able to restart the engines and safely land the plane. In this case the ash caused more than
us 80 million in damage to the aircraft (requiring all four engines to be replaced), but no lives were lost and no one was injured.As of 2010, the aircraft is still in service with KLM under the KLM Asia livery.
Dutch are stupid but also lucky sometimes
Thnx for the video, and offcourse i agree safety first.
Lets not forget also in this case the flight went through very thick cloud of dust. !!!