AIRSPEAK, also air traffic control English, Aviation English. The English of international civil aviation, a RESTRICTED LANGUAGE established after the Second World War by the International Civil Aviation Organization (ICAO). Although in some conditions aircraft may use a local language, commercial flying is universally conducted in English. When speech is necessary, it is as concise and unambiguous as possible, uses only accepted conventions for procedures and message types, is not too dense (that is, does not contain too many propositions before allowing the interlocutor to speak), and has checkbacks so that speakers can be sure that what was said is what was heard. Everything used for these purposes is English in grammar, vocabulary, or pronunciation, but some of the vocabulary is technical and specialized. Radio conversation not relevant to a flight is forbidden. International agreements ensure that all pilots are trained in this English, and cockpit conversations as monitored to ensure that rules are adhered to. The following extract, for an aircraft descending from cruise height towards its destination airport, is typical:Control. BA six zero six Alfa: squawk ident.
Pilot. Identing, BA six zero six Alfa.
Control. BA six zero six Alfa, radar contact. Descend to flight level three one zero.
Pilot. Leaving flight level three nine zero. Descending to level three one zero. BA six zero six Alfa.


[Glossary: ident identity, identing identifying, squawk reveal, make known.] See ESP, SEASPEAK.