Originally Posted by
Microwave
I actually suspect the problem has nothing to do with current or connectors. The phone is almost certainly using the USB Power Delivery specification, which allows a device to communicate with the receptacle to determine what power the receptacle can offer and what the device needs, so they can agree on a voltage and current availability. This is how USB-C can carry different voltages without harming equipment. Most USB power sockets these days provide one type of power, up to a certain amperage, and will not communicate at all with the unit plugged into it. In this case the phone probably refuses to draw power from something that won't negotiate with it.
That would explain problems with plugging it into the USB port on the plane, but not with plugging in an AC adapter, which OP indicates is also problematic.
I find that very confusing--it's hard to imagine a phone that draws more than a laptop, and I've not had a problem plugging in my laptop to the 77W power outlets.