This article is from the Vietnam FAQ, by Brian Ross, John R. Tegtmeier, Edwin E. Moise, Frank Vaughan, John Tegtmeier with numerous contributions by others.
The AC-130E's average mission duration was 7.1 hours!!!! We could
spend a heck of a lot of time in high orbit over a firebase if
needed (although we usually used the range to get to northern
Laos). If memory serves me, the AC-130A's averaged about 5.3 hours.
"The AC-119K could fly for about 3 1/2 hours, giving a TOT
on the Trail of roughly two hours or so." [RH]
 
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