They get 'paired' for various & sundry reasons. It changes all the time based on a whole bunch of things & personalities & capabilities and timing and mission requirements ... and sometimes, it's just 'first come, first served'.How are NFO/Pilots paired?
And then ... when we went to the I.O. w/ no BINGO fields in sight (Diego then was @ 5000' of Marston matting w/ Quonset huts and the Wogs said they'd 'shoot us down' if we crossed what passed for their ADIZ ... bring it ...

We left the four (4) weakest pilot/BN combo's with the beach-det @ CUBI w/ a couple of birds ... HEY!!! .... they'll be safe there, right?? RIGHT ???
Until two of 'em brought an A-6 into the CUBI break @ warp-overdrive ... THEY WERE GONNA' BE SOMEBODY (!!!!) ... and shut down both engines when he chopped the throttles ... and they didn't pop the RAT to get a re-light ... and they punched over by Grande Is.
Very jolly ...
