Just to verify:
1. The enemy airbase in question is set to generate aircraft up to "X" amount of km's from the base, depending on the base?
2. The sim "checks" if there is a sub (your boat) within that "range" of km's from the airbase.
3. If the answer to those questions is "yes", then the enemy aircraft is spawned within 30km of your boat at a random bearing and range from your boat.
4. The sim then "checks" to see if your boat is within range of the most sensitive of the "sensors" the enemy aircraft is equipped with -- whatever that "range" may be.
5. If "yes", then the sim checks for environment factors (night, waves, weather, etc.) and reduces (or adds) factors to the "sensors" on the aircraft.
6. If after all this is done the "sensors" on the enemy aircraft can "detect" your boat, then the aircraft attacks. If not, you can get away.
I'm not sure how you figured that out, but I would guess it took a while!
Let me know if that sounds about right.
Saludos!
ElCid97