What if the US Navy sends Army Aircraft to Mindanao in early 42?

If the US garrison in the Philippines made it into July or August, that would have been very bad news for the Japanese because those months tend to be very rainy months in the PI.
It's true, though, that such adverse weather wouldn't really be a hindrance to the Japanese Army but it would make things a lot more difficult for their Navy and merchant fleet. The Japanese in the Philippines would have to scale down their operations because the inflow of their supply chain would be slower than usual.
As for the defending garrison, the coming of the rainy months would allow for a little respite. However, the garrison's position would not have improved because they still wouldn't receive a fresh infusion of replacements or supplies. Still, the weather could mask the movement of small groups of men, allowing them to breakthrough the perimeter and perhaps establish a guerrilla network behind Japanese lines.

What essentially happened historically was that Singapore and the PI fulfilled the role of being speed bumps for the onrushing Japanese. The longer the garrisons held out, the more time the Allies gained to organize, consolidate and build up.

It's been several days since I last responded to this thread because I just came back from a vacation. A belated happy new year to all.

 

Yes, although neither Singapore, nor the Philippines held out as long as hoped for by the Allies. But the interesting thing is that, from the American perspective, the minimum defensive positions in the Pacific had already been decided long before the outcome in the Philippines was determined. I don't think the ultimate shape of the Pacific War would have been much changed, had either of both positions been able to delay the Japanese longer.

The US had it's war plan (Rainbow 5, AKA WP 46) and it was going to fight the war as specified regardless of what Japan did. To do anything different would have upset delicate compromises between the British and Americans in areas from Africa to the Arctic and affected strategic decisions all over the globe