looks good. i made a similar map on Halo 3. it kinda worked. basically done on that upper level on Sanbox. four plat forms with banshees on them. you can either do 2 vs 2 aor a free for all.
This map actually reminds me of Battlefield 1943's Air Supremacy gametype. If you haven't already done so, I would suggest placing the spawn bases high up in the air and then put soft kill barriers in the base and around it to prevent spawn camping.
The concept was from battlefield 1943 actually. I was halfway through a remake of it in H3 but ran out of peices Halo reach though has the island which is bassicaly the center of Coral Sea
I can't really tell much from your drawing. Dogfight is a general name which might actually be a name of one of bungie's gametypes. If also already used it, but I plan to rename my aircraft maps in Reach. Remember forced vehicle spawns are possible in Reach for races, so they should also be possible for any gametypes you plan to use.