A near disaster was avoided thanks to the robust back up systems on the Boeing 747-400. On Monday of this week a fully loaded Qantas jumbo was approaching Bangkok on a flight from London to Sydney when it lost all electrical power due to water seeping into the generator. The lights flickered as power was lost before the crew switched to the aircraft's standby power supply system. It is designed to allow the aircraft land, but not keep it in the air indefinitely, so it's fortunate that the failure occurred close to an airport. It did its job perfectly and the plane landed normally.
The Australian Transport Safety Bureau's spokesman Julian Walsh noted that the incident is "highly unusual", and an engineer told the Aussie press that the situation was rather like pouring water into a music system (but potentially with rather more dramatic consequences than melting your favourite Rolf Harris CD).