Here’s an excellent aviation anecdote from a member of a very select group of pilots…..

“One day, high above Arizona, we were monitoring the radio traffic of all the mortal airplanes below us. First, a Cessna pilot asked the air traffic controllers to check his ground speed. ‘Ninety knots,’ ATC replied. A Bonanza [a slightly larger and faster light aircraft than a Cessna] soon made the same request. “One-twenty on the ground,” was the reply. To our surprise, a navy F-18 [jet fighter] came over the radio with a ground speed check. I knew exactly what he was doing. Of course, he had a ground speed indicator in his cockpit, but he wanted to let all the bug-smashers in the valley know what real speed was ‘Dusty 52, we show you at 620 on the ground,’ ATC responded.

“The situation was too ripe. I heard the click of Walt’s mike button in the rear seat. In his most innocent voice, Walt startled the controller by asking for a ground speed check from 81,000 feet, clearly above controlled airspace. In a cool, professional voice, the controller replied, ‘Aspen 20, I show you at 1,982 knots on the ground. ’We did not hear another transmission on that frequency all the way to the coast”.

From http://flagstillstandsforfreedom.com/blackbird/

[For those who don’t know, this article is by a crewman in an SR-71 ‘Blackbird’; a high-speed, high-altitude reconnaissance aircraft that could fly very, very fast and very, very high]