English is the language of aviation :
Lufthansa (in German): "Ground, what is our start clearance time?"
Ground (in English): "If you want an answer you must speak in English."
Lufthansa (in German): "I am a German, flying a German registered aircraft, for a German airline, in Germany. Why must I speak English?"
Ground (in English) : Because English is the offical language of civil aviation.
Unknown voice from another plane (in a British accent): " And because you lost the bloody war ......"