[Veserv]

Maybe if it crashed in the ocean. If it crashed on land, then they would almost certainly find the device in the wreckage as in the Pan Am 103 bombing [1] where they found even scraps of disintegrated clothing in the suitcase carrying the bomb. The flight recorder would also almost certainly show the nonsensical inputs and outputs and the pilot confusion. And, unlike other industries, aviation does real root cause analysis to identify every factor involved in a crash so it would be exceedingly unlikely they would throw their hands up into the air and just blame the pilot or something as stupid like that.

The chances of a attack like this being undetectable are exceedingly low. You would likely need to compromise nearly every aspect of the plane to make sure you have suppressed every available cross-checking mechanism. Does not stop it from happening, but it would not, in any way, be some sort of magic assassin weapon.

[1] https://en.wikipedia.org/wiki/Pan_Am_Flight_103_bombing_inve...

[p_l]

A bit OT: The little remembered thing with Lockerbie is that they knew something was really weird before the debris hit the ground.

It wasn't the super deep check of the debris that pointed them to a bomb,it was a process that started with watching debris on primary radars fall away from a point where a moment before a transponder was squawking, it was finding the pressure spike on VCR and FDR, it was finding explicit explosion-affected parts, which guided which parts to reconstruct in 3D (very rare thing to do), and to finally find remains of the bomb itself.

[shiroiushi]

Depending on who the attacker is, the attack being undetectable might not matter. Russia has assassinated multiple people using polonium, and what was the response? Crickets. They could easily do the same thing to assassinate other people they don't like (along with plane-loads of other passengers), and the only result will be angry words and "condemnation".

[Zanfa]

I doubt those Russian assassinations were ever meant to be undetectable. Rather they were intentional spectacles, where there's no doubt in who was behind it. The goal is to make it obvious, but also deny it officially, while knowing that everybody knows they're lying, just to mock their opponents.

[shiroiushi]

Exactly. I can see them doing the exact same thing with an exploit like this. The point wouldn't be to be undetectable, but rather to be sure the assassination attempt will actually work as intended, and to cause a big spectacle (few things generate news headlines like big airplane crashes).