Crews flying the SR-71 at 80,000 feet (24,400 m) faced two main survival problems: 1) With a standard pressure demand oxygen mask, human lungs can not absorb enough of 100% oxygen above 43,000 feet (13,100 m) to sustain consciousness and life, and 2) the instant heat rise pulse on the body when exposed to a Mach 3.2 air flow during ejection would be about 450 degrees F (230 °C). To solve these problems, the David Clark Company was hired to produce protective full pressure suits for all of the crew members of the A-12, YF-12, MD-21 and SR-71 aircraft. These suits were later adopted for use on the Space Shuttle during ascent.

32 of these planes were made, 12 of them were destroyed in accidents. Between 1964 and 1998 4,000 attempts were made to shoot one of these things down, apparently none of them even came close. ]

When a surface to air missile is fired at the Sr 71 it takes the following evasive action: 
It accelerates.

Most radar systems mistake the SR 71 for a missle.