AOG work divides cleanly by size. Avionics boxes, sensors, seals, actuators and most line-replaceable units fit a cabin and travel with a courier on the next departure, which is almost always the fastest and cheapest answer. Engines, QEC kits, landing gear, thrust reversers and large structural components do not, and for those the question becomes which freighter, from where, and whether both airports can load it.
The economics are unusual in that they are rarely disputed. An operator with a grounded aircraft already knows the hourly cost, and it is normally a large multiple of anything a charter will cost. That changes the conversation: the useful question is not how to make the movement cheaper but how to make it certain, because a charter that saves twenty per cent and arrives six hours later has lost money, not saved it.
What actually goes wrong on AOG charters is almost never the flying. It is a stand that cannot take the aircraft type, a loader that is not available at three in the morning, an engine stand that is the wrong specification for the receiving station, a dangerous-goods question about residual fluids that nobody raised early enough, or a permit that takes longer than the flight. We work that list before the aircraft is confirmed rather than after.
Documentation is the other half of the job. A rotable without its certification is not a part, it is a paperweight, and the certificate has to be the right certificate for the receiving authority. We check what is travelling with the unit before it leaves, because discovering a documentation problem after a five-hour flight is an expensive way to learn it.
