“…the plane crashed on landing…”
They have a long narrow wing, like a sailplane (glider). They may have been upgraded, but in 1969, they had only in-line landing gear. On take off, two small wheels/tires were attached to the end of each wing. Upon leaving the ground, these would drop off, to reduce drag.
For landing, they used someone standing in the back of an El Camino, one on each side. They would speed down the active, match speed with the landing aircraft, and catch the ends of the wings.
So, everything has to go right. If any one of five (or more) people makes even a small error, one wingtip will hit the ground, probably causing a groundloop.
They are also said to be tricky to fly, at altitude. Not being (then) supersonic, they had to fly slower than Mach1. The higher one flies, the thinner the air.
This has two contradictory effects: it lowers the actual airspeed of Mach 1; and it raises the stall speed.
At the extreme altitudes the U 2 uses, the speed of sound and the stall speed get very close together. When the two speeds are the same, you either break up due to buffeting, or stall the wing. They call this the “coffin corner.”
DG
The El Camino has been replaced by a Camaro.
Everything else you said is correct.
It's a tricky bird to take-off, fly, and land.