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1) I landed in a KC-10 with the refueling boom fully extended. Huge fireball out the back of the plane all the way down the runway with firetrucks in hot pursuit. We evacuated using a mobile stair trunk and ran away as soon as the plane stopped. The Back of the plane was charred and the boom was a twisted piece of metal
2) Had a 777 engine seize on take off right at the point of no return on the runway. BOOM, FIRE, SMOKE. We were bussed back to the terminal.
3) 676 flaps stuck in the up position. Emergency services were alerted because they thought the pilot would have too land too fast and run out of runway or heat the brakes to the point of explosion. (Dude landed like a BOSS, used every inch of white painted runway from one end to the other, and everything worked out fine. Emergency service trucks returned to their homes unused.
All three times we were told to put our heads between our legs thus assuming the crash position. The 2) time the crew yelled it as a reflex when the BOOM happened.
Other than that I have flown 100s of times with nothing happening