Sounds like a Time Pilot clone. Not that that's a bad thing - some of those clones had cool stuff the originals never did.they had BBC Micro's at my priimary school. we used to play Chucky Egg and Space Pilot on it. i much preferred Space Pilot.
for those not in the know, Space Piot was a side-on flying game where you flew a fighter jet against WWI biplanes, then advanced to WWII Messerschmitts, Vietnam and helicopters the Falklands and Harriers and then flying saucers in the future. the WWI boss was a zeppelin, the Vietnam one was a Chinook.
no, i thinkit was 'time pilot' and i got the name wrong. hey it's 20-some years...!
Definately Time Pilot. One of my favorites! I still play it on the DS from the Atari Arcade Classics for gameboy advanced.