K:

Clay Blair points out something very interesting relative to air patrolling.

The US Navy was against it at first. Heavy bombers were the enemy to the Navy and a feared competitor in the 20’s and 30’s in terms of funding. This ultimately was a good thing, because it made the Navy develop better fighters in order to keep up with the AAF bombers. In the mid-30’s the Navy found itself in the embarrassing position of having fighters that were slower than the early B-17’s

The USAAF was for it, and had the first B-24’s equipped with air to surface radar. But they did not know how to do it, had not trained the crews in ASW, and never tried to master convoy escort techniques, where the aircraft hung around the convoys that were the targets. Aside from that, conventional bombs were all but useless against U-boats and the depth charges of that time could not be set to explode at a depth shallow enough to sink a surfaced U-boat.

The Battle of Midway changed the USN’s view on heavy bombers. The PBY’s they used for scouting spent much of their time running away from Japanese aircraft, ANY Japanese aircraft, not just Zeros but even bombers. The USAAF B-17’s not only located the Japanese fleet but overflew it with near impunity. Initially the USN even put Navy observers in USAAF bombers. Then the USN started acquiring B-24’s and eventually extensively modified it into the PB4Y-2 patrol aircraft.