[Fincuan]

USN/USMC pilots were trained to avoid stern attacks like the plague and favored side attacks. From head-on they used the overhead (vertical dive) approach if they had an altitude advantage on the bomber.

That's good advice against any bomber, but especially against the G4M Betties US pilots often encountered. The 20 mm stinger in its tail REALLY hurts when it hits, so tail-attack is especially no-no against it.