Could an SR-71 signal in Morse code with its afterburners?

Could an SR-71 crew signal in Morse code by switching the afterburners on and off?

The story is doubtful if the claimed ignition limit applied. Repeated reheat cycling and the short transit time would make this an unlikely signaling method.

The anecdote claims that an SR-71 crew signaled in Morse code by switching its afterburners on and off over hostile territory. A viewer objects that the aircraft had limited ignition attempts, several of which were needed for starting, takeoff, and refueling. If that limit applied, repeated reheat cycling would be an unlikely signaling method. The Blackbird's speed would also leave little time over the intended area.