Loose seal resulted in flooded B-1 turbopump and low thrust; sustainer engine compensated by extending burn time, but the upper stage ignited while still attached to the Atlas and was left in a useless orbit.
Loss of turbopump lubricant caused B-1 engine shut down just prior to booster jettison; vehicle flipped around 180° and descended back towards Earth, breaking up as it fell.
B-2 engine shutdown at T+7 seconds due to sealant plugging up the gas generator; vehicle destroyed by Range Safety Officer just before impacting the ground at T+20 seconds[1]
Launched into a thunderstorm. Booster was struck by lightning shortly after liftoff, damaging the guidance computer and sending an erroneous pitch down command that resulted in vehicle breakup.[2]