Why not add radar like Elite or WingCommander had? Two circles, one forward, one rear, with colored dots for each aircraft in the area, two axis in space represented by the flat circles, fading for the 3rd dimension.
It would for sure help fights. That is, it would help players who have optimized their strategy to fly with such radar. That may very well be valid in certain games.
Its WW2, there was no in-flight radar (bring the night-fighters...). Radar serves the purpose of roughly finding the enemy, and getting a pre-warning when fields are being attacked (maybe not early enough though). It's not a computer to generate an optimized intercept course. Map icons showing heading (especially also for enemies) is already too much for my taste. When radar is down, it has already done it's job: You can be sure that there's an enemy in the vicinity.