This comes to my mind after I read all the wiki pages that out of all Strangereal player characters (excluding Nemo, who is an A.I.), it seems that Mobius One is the only one whose military rank is never stated / addressed.
I thought of several probable things :
1. He might be wearing a naval officer rank, since by the way he began as a carrier-based fighter pilot, he might be (and perhaps the only Ace Combat player character) from the Navy branch (all of the other player characters are from Air Force branch).
2. Since he made his debut as a rookie, Mobius One's starting rank at the beginning of AC04 might be either Ensign or Lieutenant junior grade / Sub-Lieutenant.
3. The way he quickly rose to fame throughout the Continental War and the respect he earned from ISAF, I think that his last known rank is either Lieutenant Commander or a Commander.
It is really impossibel to know since as you said it's not addressed in the game.
I wouldn't read much into the starter plane as any number of explanations could be given for that due to the situation the game starts with.
Most of the player-characters start out as rookies or unranked, the story telling how their exploits coincide with the rise in rank. It wouldn't be surprising then if Mobius started at the lowest rank.
His final rank is likely very high due to the numerous achievements and commendations. The final mission he is in command of his own Mobius Squadron, so he likely had the rank of a high-level commander. Furthermore the after-war mission certainly suggests that he has the rank enough to be left to handle decision-making on the battlefield in attacking the remnant forces. As unlikely as it is for that to happen, it could well be that Mobius One was a General still flying combat missions by the time we see him in Operation Katina.
It should be noted that the majority of player characters who have been given ranks was the result of fanon. Typically, the military rank of the player character is never addressed, as was the case with Mobius 1. Cipher certainly never had a rank, and I don't believe Gryphus One did either. Blaze obviously had a rank until Wardog Squadron was disbanded, and Colonel William Bishop... well. Colonel. xD So the idea that Mobius 1 didn't have a declared rank isn't uncommon to the series; it's more common.
SlyCooperFan1 wrote: It should be noted that the majority of player characters who have been given ranks was the result of fanon. Typically, the military rank of the player character is never addressed, as was the case with Mobius 1. Cipher certainly never had a rank, and I don't believe Gryphus One did either. Blaze obviously had a rank until Wardog Squadron was disbanded, and Colonel William Bishop... well. Colonel. xD So the idea that Mobius 1 didn't have a declared rank isn't uncommon to the series; it's more common.
Result of fanon ? So, that might explain on Blaze's wiki page that he held the rank of Brigadier General while it's never mentioned/addressed in-game.
I think Gryphus One's rank is Captain. Remember on the 1st mission of ACX where one of his wingmen said : "After all, we're Aurelian pilots. Isn't that right, Captain ?" and then responded by Crux who told him to "use codenames during the mission". Well, at least for the beginning of the game.
I agree with the idea of anonymous rank being common in AC series, so it may be left to the players' imagination.
AC2 on PS1 is a good example of this where the players' rank rose dynamically depending on their performances in the game.
^ I would say the use of "Captain" in that conversation in ACX may not have been referring directly to rank, but to position. It's a common salutation to greet a team, unit, squad, etc. leader as "captain" even if that's not their official title or rank. For instance in the Navy, the "captain" of the ship is rarely actually of Captain rank - they're usually above that at commodore or rear admiral. Captain is also below Major in the air force, above lieutenant, so while possible it's hard to say what exactly his rank would be. There are enemy Aces who are ranked at Major or higher, so it's probable the player character would be the same or higher rank by the later stages of most AC games.
DRosencraft is correct. Take the dialogue of Rendezvous:
Chopper: << Hey, Kid! >>
Grimm: << You really should start calling him Captain. >>
Chopper: << Forget it. If he's a Captain, then I want him to start trash-talking like a Captain. Man... I'm missing that voice real bad now. >>
Grimm: << He's gotten us out of battle for the second time now. As far as I'm concerned, he's our Captain now. >>
The term "Captain" is used as both a military rank and for the position of squadron leader. The members of Wardog weren't actually ranked as Captains until the events of Ice Cage and White Noise, when they got promoted. So the case of "Captain" being used in ACX is likely the same as here, where it was for the position as squad leader and not actual military designation.
SlyCooperFan1 well about military rank in pilot as commonly happen in real world was a colonel for the highest rank.And when became colonel means he became also as air Base commander like colonel Orson Perrault on Ace combat 5.So if he has more higher rank than colonel is almost like too far to imagine or being taking as possiblity carreer that being adaptive into game.My answer also the point of my theory is he and other protagonist rank is major.like Hamilton on ace combat 5 that still into battle with usual because he still major and being position as vice commander air base.Yellow thirteen I guess should be major or higher like colonel also because posthumous rank promotion A.K.A because died in battle like chopper on ace combat 5 who receive two rank promotion for K.I.A means it died character have possibility noted to most higher rank to be achieve by posthumous rank other than that no matter how many operation he done he only collect medal without promotion