Nobody gets paid on block time only, so it's not that.
UA blocks the 789 about 30 min slower than the 744. The MU 773 should be about the same as a UA 789 in terms of what the airframe can do, may be different choices in padding or cost indexing.
Code:
carrier | origin | destination | equip | min | avg | max
---------+--------+-------------+-------+-------+-------+-------
MU | SFO | PVG | 332 | 14:05 | 14:27 | 15:10
MU | SFO | PVG | 773 | 13:30 | 14:09 | 14:30
UA | SFO | PVG | 744 | 12:35 | 12:57 | 13:25
UA | SFO | PVG | 789 | 13:25 | 13:25 | 13:25
SFO-ICN there's less of a difference, except that OZ seems to be blocking long for their non-freighter flights. The UA 744 is no different than the KE 74H (748). UA blocks the 777 longer, but it's comparable to SQ 777.
Code:
carrier | origin | destination | equip | min | avg | max
---------+--------+-------------+-------+-------+-------+-------
KE | SFO | ICN | 74F | 12:45 | 12:45 | 12:45
KE | SFO | ICN | 74H | 11:45 | 12:22 | 13:00
KE | SFO | ICN | 74N | 12:45 | 12:45 | 12:45
OZ | SFO | ICN | 74E | 13:00 | 13:00 | 13:00
OZ | SFO | ICN | 74F | 12:30 | 12:30 | 12:30
OZ | SFO | ICN | 772 | 13:00 | 13:00 | 13:00
OZ | SFO | ICN | 77L | 12:15 | 12:59 | 14:00
SQ | SFO | ICN | 77W | 12:35 | 12:43 | 12:55
UA | SFO | ICN | 744 | 11:55 | 12:12 | 12:30
UA | SFO | ICN | 777 | 12:40 | 12:40 | 12:40
UA | SFO | ICN | 789 | 12:25 | 12:25 | 12:25