The only occasion I have ever heard of when air traffic control and air crews don’t speak English (or rather spoke, I have no idea what it’s like nowadays) was domestic flights in the Soviet Union.
It’s been said that it takes about a day of conversation between a Norwegian and a Swede to get so used to the other language that they don’t have to actively translate it in their minds and a week for either of them to understand a Dane to the same degree. Heck, not even Danes understand each other.
I once listened to a Finn describing something in Swedish. She was obviously very uncomfortable speaking the language with a bunch of colleagues from Sweden and eventually she asked if she could continue in English. Naturally we told her to go ahead, but unfortunately if her Swedish was bad her English was horrible.
Just for the record, a couple decades ago, the question arose of whether a French Canadian pilot was permitted to speak French to a French Canadian air traffic controller. This of course, got into linguistic politics in Quebec than which there can be no fiercer battles. Some Air Canada pilots said they would refuse to fly into Quebec in that case, since they felt it was a safety issue that they be able to eavesdrop on all tower communication whether it involves them or not. Then the company said okay, pilots could ask not to fly into Quebec but any who did so would not be allowed to fly overseas. The pilots quickly changed their minds.
So I think you can speak your native language to a controller if it is also his. Otherwise, all conversation with the tower is in English.
I believe that when heads of state meet formally, they always have an interpreter, even when they understand perfectly well the other language. It is a matter of protocol. When they meet informally, it will depend on their fluency.
I frequently hear Cuban Air Traffic Control if atmospheric conditions are right. Their communications with international flights in overflight is in English but they occasionally use Spanish when directing domestic flights.
Half this thread follows the assumption that the two people do not have a common native language, but keeps leaving it unstated, while actually there are many, many cases in which they will. Even in the cases when they don’t, often the translators are there as “living dictionaries” for when “their” dignatary can’t remember a word, rather than to provide constant translation.
I could also see them using interpreters in order to save face for their own constituents. Let’s say the King of France meets with the Emperor of Germany. Being well educated sorts, both are fluent in French, German, and the language of shared business, Dutch. If it’s a public appearance, they might talk through interpreters so that neither has to use the other’s language or a third language, even if they personally have no problem doing so.
If they make a public appearance, the King of France and the Emperor of Germany will i) not need translators as people will be so amazed at their return after decades and centuries of being dead and ii) will probably no longer have vocal cords due to decomposition and finally they will want the brainsssssss.
Moreover, at there was never a French King and a German Emperor at the same time and if you count the Holy Germ…errr Holy Roman Empire, it would be at times when latin or later French were diplomatic languages anyway.
A similar thread I started back in 2011 on the same topic. However, it was more specific to Merkel and Sarkozy who were frequently seen speaking to each other.
