I don't worry about the weather. The Gorn is right, the 'mail' must be delivered rain, sleet, or Himalayas. I'm not sure if it is optimal, but here's how I approach it:
1. Train all pilots in the squadron to a TRANSPORT skill of 70+ before flying supply missions.
2. Build up the departure and destination airfields as much as possible.
3. Make sure there is enough aviation support at the departure airfield; I'm not sure if the destination aviation support matters.
4. Fly at 20k ft or similar altitude.
5. Set squadrons to 50% rest - you can get away with a lower % for a time, but fatigue will of course build more quickly. 50% makes sense to me for long-term ops because each aircraft/pilot essentially flys one day and rests the next.
6. Stand down any squadrons which reach "X" fatigue level - I usually do this at fatigue of 7+, but this can be adjusted as needed.
7. Set range for regular radius only; only fly extended radius if absolutely needed and only for short durations.
8. Fill the squadrons up with aircraft, including maximum reserve aircraft as availability allows.
9. I haven't been diligent about it, but high Inspiration leaders allow faster regain of morale and high Leadership leaders are good for training squadrons (faster exp gain).
10. If possible (and there aren't higher priority assignments for it), locate an air HQ at the departure airfield and assign all transport squadrons to it (also, if the political points are available and there aren't higher priorities for them).
11. Use the older C-33s for training squadrons as much as possible, and save the newer C-47s and C-46s (when available) for the operational squadrons.
Even with all this, losses will still be regular. In mid-43, all my full size (i.e. 25 aircraft) C-47 squadrons flying the hump have total OPS losses in the twenties and one is as high as 36. Also, suspending all construction, LCU replacements/upgrades, and base repairs in China and then selectively turning them back on goes a long way towards conserving the few supplies that trickle in via air transport. Also, be very selective about deciding to attack with your LCUs in China - even when successful, they will eat up supply.
< Message edited by Korvar -- 1/19/2019 9:08:05 PM >