The first flight of the day 6:30am from SAN to SFO has been pretty empty on Tue. Maybe 1/4 full, but I doubt even that much. Has left early twice so far 6:20 - once when everyone checked in. A 2nd time when I heard the captain say in response to "still one not here, checked in yesterday online" with "let's go"

The Thur night 9:15pm SFO SAN seems to run 1/2-3/4 full on the 2-3 times I've taken it. (Compare with the 8:30pm Southwest flight which is usually 2/3-all full, and 15-30 mins late).