If planes aren't in orbit than RET is wrong, because in RET everything is always in orbit around something else. In RET, a plane would be in orbit around the Sun, just like the rest of the Earth. How are you supposed to defend RET if you don't even understand your own rules?
By that logic, if a butterfly flaps it's wings in Japan, then we have to account for that in every other scientific experiment, and if we don't, then we don't understand how butterflies work. If we don't understand how butterflies work, how can we possible defend anything!
You could quite easily calculate the forces of gravity on a plane from the sun, the moon, mars, jupiter, polaris, anything you want. But it's obvious those forces are negligible... By far the most important forces for a plane are gravity (towards earth), lift, thrust, and air density i.e. resistance to that thrust. The earth is really really really heavy... a plane is not. Given the atmosphere moves with the earth, and planes exist in that atmosphere, that's all the plane cares around.
In one way, as a complete system, then yeah everything on earth is in orbit around the sun. But that's just one way of looking at it. The atmosphere is tiny... roughly one millionth of Earth’s mass... so is the atmosphere orbiting the sun? Erm, in some ways, but for all intents and purposes, it's the solid mass of the earth itself which is in orbit around the sun. Everything else is just "hanging out" and hardly gives a crap about that orbit. The atmosphere, and planes, only care about gravity towards the earth. If you shot a plane in to space at the same distance as the earth from the sun (and nowhere near the earth), it would very slightly be attracted to the sun but just end up flying away for every. So obviously no, a plane is NOT in orbit around the sun... the only thing that's keeping it in roughly the same path as earth's orbit is that the plane is being pulled towards the earth and affected by the atmosphere.
The only thing that's keeping the atmosphere on the earth is the gravitational pull towards the earth: the atmosphere is not in orbit around the sun, it just follows the same path as the earth's orbit around the sun. So yes: from a simplistic "path" point of view, everything is on the same path as the earths orbit, and for the sake of argument, most people would just say "everything orbits the sun". As for "everything orbits something else".... that's not a universal law, i.e. if the universe consisted of only two masses, then they could just be attracted to each other and stick together permanently, or if they were moving for some reason they might be attracted to each other then begin orbiting each other. And obviously our sun formed when objects stopped spinning around something, and were attracted to each other in to one giant blob. But our sun orbits the black hole at the centre of the galaxy.. and apparently our galaxy doesn't really orbit anything: we're on a collision course with the andromeda galaxy. So there's that to look forward to... But yeah, asteroids usually orbit something (usually the sun) or sometimes asteroids from outside our solar system swing by to say hi, usually because they've escaped an orbit from a nearby sun. Things don't HAVE to orbit anything, they just fly around attracted to other masses. If they end up circling that mass, we call it an orbit.
But... getting back to satellites. They clearly couldn't stay in the air without generating "lift" and they can't generate lift without fuel, and they can't get fuel without returning to earth or being refuelled mid air (and obviously no one has ever witnessed that, and pretty sure every single amateur astronomer is not in on the "RE conspiracy"). OK they could be solar powered... but they would then need to be lower enough in to the atmosphere to get that lift from their wings. Satellites are much higher than the atmosphere, so they would need lift from rockets. That requires a lot of fuel.
Plus you realise there are geosynchronous satellites right? So there goes the giant solar wing idea... They would need to just sit there, rockets blazing, keeping them in one position, year after year. Again: amateur astronomers. You should see a blazing stationary rocket during day light, night time, 24 seven.