Chart of Allied Aircraft Losses by month ?

[GuerraCivil]

Simple answer: one is a complete original report written after war, the second is a incomplete web transcription. Original report is usually better than later made transcription of it.

To put couple of examples. http://www.usaaf.net/digest/t161.htm - gives that the total losses (of all causes) on Pacific Ocean area combat mission by USAAF planes were in total 378 between Jun. 1942 - Aug. 1945. Firstly this is incomplete as it does not include the time period Dec. 1941 - May 1942. But putting that aside the original report show that alone in 1943-1944 USAAF lost 346 planes in combat+first rate accidents in Pacific Ocean Areas and in total such losses in. Dec. 1941 - Aug. 1945 were as much as 1054. Even if you take 50 % of them accidents at airfields, it will make more than 500 lost in combat missions for all causes, which is clearly more than your link gives.

Secondly your link does not include FEAF losses - if one wants to get the picture of the plane losses of US Army air units during the whole Pacific war, they should be included. Alone in 1942 the FEAF lost 813 planes in combat + accidents in Pacific war.

The problem is to some extent how to define the boundaries of "Pacific war".

And to combat losses should be included all those planes which were destroyed on the ground by enemy bombing and strafing attacks.