Earlier quoted context omitted.
> Another pilot chimed in: "Only in LA." The SR71 radio speed check was in LA too. I heard a Cessna ask for a readout of its ground speed. '90 knots Center replied. Moments later,a Twin Beech required the same. '120 knots' Center answered. We weren’t the only ones proud of our ground speed that day as almost instantly an F-18 smugly transmitted: 'Ah, Center, Dusty 52 requests ground speed readout.' There was a slight…
That story is often told but is generally considered apocryphal. There is too much wrong with it procedurally. It's funny, but not likely a conversation that actually happened.
Not saying it’s impossible that he made it up or embellished, but it seems likely that it actually happened.