Yes, it does not matter which territory the troops on the transport are invading. The amphibious assault is in the sea zone adjacent to a territory with an airbase, which is all that is required.
Marsh
Okay so situation. Germany has 6 transports and a destroyer in SZ112 they move them into an empty sz110 for an amphibious assault on London. UK can scramble 3 fighters to fight the German sea units. Can Germany fly aircraft into sz110 in there declare attacks phase in order to cover their transports?
Yes. Germany can fly as many planes as they want, that can make it with a legal landing zone, into the Sea Zone during the Combat Move Phase.
@andrewaagamer Thanks!