To keep your pilots alive forever, make a copy of the
 PILOTS.DAT file before going on a dangerous mission. If you
 get killed, you can copy the file back and your pilot is
 resurrected - as though he had never flown the fatal mission.

 For example, to copy the file, change to the Aces directory
 and type:
 COPY PILOTS.DAT BACKUP.XXX
 To resurrect a pilot, change to the Aces directory and then
 type:
 COPY BACKUP.XXX PILOTS.DAT
 Make sure you copy the PILOTS.DAT file every time you
 successfully complete a mission.