A scientific research helicopter has crashed in Antarctica, killing its German pilot and a Dutch technician. Jan Boon of the Netherlands Institute for Undersea Research says the cause of the crash is not known. Three others were injured in Sunday's accident, which happened under clear skies. The helicopter was shuttling between the German ship Polarstern and German research base Neumayer II on the icy continent when it crashed. Three other passengers were injured, two of them seriously, according to the Alfred Wegener Institute (AWI) for Polar and Sea Research in Bremerhaven,