Ok so in advance, sorry if this was already addressed. But I just realised this logical explanation.
We know the heat sensors can be configured (even in post processing) to certain levels.
If we take the bottom image as a base look for an airliner heat signature, it indicates the abduction footage is much much colder and had to be tuned down on the heat levels.
Tuning it down would result in the plane look colder (unlike the “normal” hot version) and the reason for this tune-down would be to reveal the UFOs.
It is quite visible even with tuned-down heat levels that the objects look almost as cold as the environment and only the Sun light reflected on the top is showing any substantial heat levels.
So the temperature of the plane is probably higher (and correct) and the visual footage was simply adjusted to reveal the UFOs that would be, under normal heat levels, quite invisible to human eyes as they would blend in with the temperature of the sky/environment.
Just my 2 cents…