I think their graduation rank depends on coursework, degrees, and merit promotions. For a real world example, a person attending University on a AFJROTC scholarship graduates college with a BA/BS and a Lieutenant's rank. I don't find it too hard to believe that as long as they also finished University coursework while at the academy, they finish with a higher rank.
Enlisted ranks are completely different, and generally do not involve the Academy in canon.
Direct quote from MA: In Starfleet, an enlisted crewperson is one who has not completed the four-year Starfleet Academy course. In most cases, enlisted crewmen sign up directly to a ship or posting, and receive basic training, as well as any specific courses required for their position. (TNG: "The Drumhead"; DS9: "Shadowplay", "Starship Down")
My understanding is that they are wearing their pending post-graduation ranks when they are onboard the Enterprise, so I wouldn't call it a field promotion per se. Otherwise every single cadet on the ship would have been an Ensign as you say.
Just my idea on the whole affair from my military experience (not personal, but about everyone else in my immediate and extended family,) feel free to ignore me. ^_~
EDIT: Also, I wonder how much SF has been influenced by outside ranking systems, both Terran and beyond. It sounds handwavy, but it could be completely plausible. As for the rank jumping, it tends to happen in historically tight or crisis situations. Tends to lead to a glut of upper ranking individuals post-war (the Civil War was one, but it has happened manymany times.) It's all interesting to me. :D
no subject
Gaila is, of course, of unknown rank in canon, but several of the other Cadets are of higher rank (as indicated on their sleeves)
Bones: Lieutenant Commander
Sulu: Lieutenant
Chekov: Ensign
Uhura: Lieutenant
I think their graduation rank depends on coursework, degrees, and merit promotions. For a real world example, a person attending University on a AFJROTC scholarship graduates college with a BA/BS and a Lieutenant's rank. I don't find it too hard to believe that as long as they also finished University coursework while at the academy, they finish with a higher rank.
Enlisted ranks are completely different, and generally do not involve the Academy in canon.
Direct quote from MA: In Starfleet, an enlisted crewperson is one who has not completed the four-year Starfleet Academy course. In most cases, enlisted crewmen sign up directly to a ship or posting, and receive basic training, as well as any specific courses required for their position. (TNG: "The Drumhead"; DS9: "Shadowplay", "Starship Down")
My understanding is that they are wearing their pending post-graduation ranks when they are onboard the Enterprise, so I wouldn't call it a field promotion per se. Otherwise every single cadet on the ship would have been an Ensign as you say.
Just my idea on the whole affair from my military experience (not personal, but about everyone else in my immediate and extended family,) feel free to ignore me. ^_~
EDIT: Also, I wonder how much SF has been influenced by outside ranking systems, both Terran and beyond. It sounds handwavy, but it could be completely plausible. As for the rank jumping, it tends to happen in historically tight or crisis situations. Tends to lead to a glut of upper ranking individuals post-war (the Civil War was one, but it has happened manymany times.) It's all interesting to me. :D