Answer: airalert

AnswerCrossword Clue
AIRALERTPre-sortie signal
AIRALERTWartime warning
AIRALERTWartime signal
AIRALERTFighter squadron's signal
AIRALERTSignal to combat pilots
AIRALERTSignal that starts a scramble
AIRALERTEnvironmental warning
AIRALERTSortie signal
AIRALERTNoise heard during the London Blitz
AIRALERTWarning during the Battle of Britain