It's from an old post but assuming things haven't changed too much:
"Classing Fighters:
Example pilot : US - full EBVE level 120
1) Classed only figher: 650 crew - 3703 ability displayed - 260 vets max
2) Classed ace pilot : 590 crew - 3919 ability displayed - 236 vets max
3) Classed sq leader : 545 crew - 4027 ability displayed - 218 vets max.
So based on adalbert guides for true ability calculation (lets assume full crew for all cases and 0 rokies to make the other factor 1):
(4*Nvets + Nexp)*(abilty displayed) = true ability
Lets review with our example pilots at diferent vets value:
109 vets - 150 vets - 210 vets - 240 vets - Max vets (#)
1) 3'015,022 - 3'394,600 - 3'950,080 - 4'227,820 - 4'412,980 (260vets)
2) 2'994,922 - 3'396,640 - 3'984,520 - cant reach - 4'239,268 (236vets)
3) 2'926,432 - 3'339,220 - 3'943,300 - cant reach - 4'023,844 (218vets)."
Squad looks worst in all situations.