I asked how the submarine would know the airplane or helicopter was around and where it was. Since you’re so up on the details of shooting down the airliner then surely you can answer those simple questions.
I was not a Navy guy and so I cannot speculate on how to detect aircraft from underwater.
OK, I will speculate: It would be safe to assume that the sub may be able to detect the acoustic signature of an aircraft since they can identify specific enemy boats by their unique signature.
BTW, one of my other contributions was a way of detecting submerged craft from space sensors. It involved the use of a very advanced chip that one of our subcontractors had developed. The guys in San Diego really loved that one.
That's quite easy. An helicopter is a thread to a submarine when a dipping sonar is used. That sound can easily detected an located by a submarine. The ASW helicopter is located just a few meters above the sonar.
A submerged submarine can't detect a flying aircraft except you have systems like this:
http://maschinenbau.gabler-luebeck.de/en/entwicklungen/kommunikationssysteme/
http://maschinenbau.gabler-luebeck.de/en/entwicklungen/eigenschutz/index.html (VOLANS)
Maybe some captains can aim at the track of sonobuoys laid out by an ASW aircraft. The sonobuoys had to go active immediately. It's also possible to just see an aircraft via periscope but then the submarine is at snorkeling depth. A deep flying ASW aircraft might be a good target. This could be the answer why P-8 Poseidon is not flying as low as a P-3 Orion.
A nice option is to attack coastal installations. Submarine gets target coordinates and attacks without any armed UAV flying around.