In article ,
Mark Schaeffer wrote:

[...]

The A-12 was the first aircraft to reach Mach 3 and return in one
piece.

[...]

What are the dates for A-12 and X-15 first flying at Mach 3.0+?

THe F-15 didn't do it in one piece. It left a B-52 behind.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.