Well the jump seat is present for many purposes. In the Boeing B-17, there was no dedicated panel or station for the flight engineer, and a seat was able to easily sotre, and pop up when he was needed to lean the engines. In modern jets, the jumpseat is also an extra seat in the cockpit, where, in instances of a long-haul flight, the extra pilot can sit and help with checklists before flight. The jumpseat is also a place for an extra pilot to sit, in the event that there is the need for navigational assistance, or technical assistance. The jumpseat was used in the instance of United Flight 232, when a DC-10 pilot riding in first class, was brought into the cockpit to assist the two pilots manuevre the aircraft, when all controls but throttles and slight elevator trim had been lost (the FE was busy with other stuff).

Jumpseats are used today also for commuting pilots, when there are no more seats in the main cabin, a pilot from that airline, or another, can be seated in the cockpit, whether he is commuting, or in some instances, a pilot for that airline can personally travel and sit in the jumpseat.