i would guess it was a "random group" of whatever type of planes it turned out to be.
the random group will be invisible in the campaign.RND layer and will follow preset waypoints. SH3 decides to spawn them based on weather and a random percent chance... just like a convoy or any other non-scripted ship.
in a case like i have just described... it does not matter if you sent a report or not. it sounds to me like you came across the planes just by pure chance
however, sending a report increases the % chance by some margin that aircraft will respond.
SH3 knows where airbases are in the game even though they might not appear on the map... and SH3 also knows which types of planes are "based" at the airport.
when you send a contact report SH3 basically looks at 3 things
1. distance between you and the nearest friendly air base
2. weather condition
3.% chance that aircraft would respond to your report
when SH3 is satisfied that
1. the distance between you and the air base falls within the operational range of the planes at the nearest base
2. weather is good for flying
3. % chance of aircraft response is above "X" percent
planes will probably show up.
however if SH3 rules out air support by nullifying any of the 3 conditions planes will not show up to assist based on your contact report.
for example if the weather is bad, or if the nearest air base is too far away. the % chance of aircraft spawning and assisting you automatically drops to zero.
hope this makes sense.
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