The 747 is the only airplane in the UA
fleet with enough seats to cover a flight on the six 2-class 777-200s. Since there are no spare 2-class 777s, when one has maintenance (either scheduled C check or unscheduled), a flight will get swapped with a 747. UA
prefers to swap them out on domestic turns from SFO
which is a 747 pilot base, but sometimes the 747 will end up flying to HNL
operates several routes as virtual spare routes. The SFO
route is known to routers and dispatchers as a sacrificial route if they need the 2-class 777 elsewhere. UA
will do the same with SFO
. Anytime there are irregular operations, those are the routes that have the widebodies swapped out. It’s not fun for the passengers to not get the widebody they planned and the gate agents having to redo all the seats, but operating sacrificial widebody routes between the hubs is one of the strategies that helps UA
maintain very high international departure dispatch reliability.
If you have never designed an airplane part before, let the real designers do the work!