I like Tony's proposal. One question though. If we don't actually weigh planes before each flight, how would we make sure that the tank hasn't been underfilled at the weigh-in, and overfilled when it comes time to fly? Isn't there a risk that protests and challenges will become the norm, slowing the flight line to a crawl?

Given this, would it make more sense to require that whatever tank is in the plane, that it be filled to overflow? This way the amount of fuel at take-off can't be increased without changing the tank, and the tank that was used in the weigh-in could get a sticker or something to prove that the same tank is being brought to the flight line.

Now that I think about it, maybe stickers should be used for battery packs as well. Otherwise it's all too easy to show up at the weigh-in with a light pack, and then fly with a heavy pack.