Summer light very early mornings and late evenings can be just as good as winter light, providing you can get close enough to your subject for haze not to become an issue. I am lucky in that I live only a few miles south of
MAN, which offers some of the best close-up photography of airliners not just in the UK, but arguably the world.
Whether it's summer or winter, getting as close as you possibly can to the action is about the only way to eliminate (or at worst reduce) heat-haze. Another trick is to try and get some elevation, although you'll still need to be fairly close to your subject. In summer, there's little point in shooting aircraft just above or on the ground, unless they are close enough to require wide-angle (a 320 on the deck at 30mm or under shouldn't show any signs of haze, providing it's free of jet-blast or APU exhaust).
You really do have to be surprisingly close to avoid haze; even at the 23L mound at
MAN - where a 320 requires about 60mm - you'll begin to see haze in June after about 0800. The RVP is about the best place, because you are ridiculously close, and the mounds give you some decent elevation. The downside, of course, is that the north side is only good for the light between early March and early October.
Karl