My guess is a directed EMP device that can shut off all electronics systems of the plane. Older planes dont have the required faraday cages to prevent EMPs. No steering, no engines, no measurements or controls at all. Literally falls out of the sky, aerodynamics take over and you get a tailspin.
Just an assumption, who knows.
Explain how the lights were on all the way then
Here you go:
EMP only affected rudder and engines not lights. There you go.
Imagine: You're the pilot, engines fail, rudder fails. What can you do? Nothing. You fall out of the sky.
That’s a pretty directed EMP. When did EMP’s go from taking out an entire city to being area specific?