Unlikely is not never, nor even is unlikely squared.
Ask the pilot whose vacuum and electrical systems failed all at once.
Serial improbabilities confuse us even more.
An instructor watches a student fly past the glide slope. How can this be? The needle clearly shows the glide slope well below.
But only on the instructor's side. One alternator's failure made the pilot's needle stick. Reason enough to devote essence to the cross-check, the mental game that the marker should be crossed at just this height, the descent rate this multiple of the ground speed, this many minutes and seconds to the ground.
Two pilots cross-check each other, one calling "glideslope!" the other expected to call "correcting?" When the other's reply is "What do you mean, the needle hasn't moved," both know it is time to go around.
One pilot must have the essence to think the thoughts of two.
The other alternator fails, unlikely squared has occured. Now all the needles come to rest.
Preflight essence spent on warnings and procedures now gets burned. One flies, one tries to get the electrons to flow again. Failing that, one flies, one tries to lower the wheels.
Perhaps the tower is called from a mobile phone. The only charged battery aboard.
Perhaps, in the end, nothing happens.