Actual flights may involve situations such as diversion to an alternate airport due to
the sudden worsening of weather conditions, diversion back to the airport of departure due
to serious aircraft malfunction, crew incapacitation in which the crew cannot perform
their tasks or trouble in the passenger compartment. Any of these given occurrences would
result in a sudden increase in the workload of the pilots. Fatigue accumulation during
long flights or malfunctions that occur during the absence of a member of the flight crew
member from his seat in the cockpit also greatly increase workload.
Actual flights where procedures had to be improvised because they were not conceived of in
the operation manual or where circuit breakers had to be operated have been reported. In
these circumstances the night crew was required to somehow manage to contrive procedures
to maintain the safety of the aircraft and the passengers on board.
It is only the three man crew complement that enables the flight crew to perform these
operations with some extra time in reserve. In the two man crew complement, it would be
difficult to perform the same operation. It would require cutting down on some of the
necessary operations, giving up the cross monitoring or the backing up ofeach other. One
pilot would have to play the role of flight engineer while the other conducts a one-man
operation. In times of emergency, the two man crew which does not have the time reserve,
will have to cut back on some measures that enhance safety in order to continue operation.
There are many safety problems in the two man crew complement of large aircraft. The
factors of the Bight engineer in a three man crew complement will be evaluated.