I recall a British pilot being killed in Paris CDG as a direct result of the Tower not speaking English in the airwaves.

Apparently Air France Pilots refuse(d) to speak English when in Paris CDG and other French airports. They were at one point told to speak English but they threatened to strike so that order was revoked.

One dark evening in CDG, the pilots, ground and tower were twittering away in French when a lone British Shorts 360 was taxiing for take off. Neither of the crew spoke French, so had no situational awareness as they could not listen in to the movements. As a result they did not realise the tower cleared them to cross a runway that a flight was departing on.

An Air Liberte MD80’s wing sliced right through the cockpit of the Shorts 360, killing the co-pilot.

I seem to recal some official body damning French ATC for not instructing traffic in English