Here's a link to some info about a recon plane:
http://www.answers.com/topic/mitsubishi-ki-46
Look at the range: 4,000 km (2,485 mi)
On the map that came with the game is the air cover for Japan 41-45
and it's radius is 600 mi. And, depending on implementation we should expect
more air cover once Wake is captured.
The file airstrike.cfg gives as aircraft range:
Maximum Aircraft Range=2500 ;[>0] in kilometers
Sounds reasonable. Even the Zero had a range of 3100 km:
http://www.answers.com/topic/a6m-zero
The planes are pesky, even more once they've found you. The probability for
airstrikes raises, check the airstrike.cfg file in the CFG folder for the numbers.