The rules are aimed, in part, at preventing businesses or charities from taking passengers for joyrides in sometimes risky planes. "That's a valid rule. They shouldn't be hired to do that. But it wasn't written, I believe, to stop a wildlife reintroduction," Joe Duff, an Operation Migration co-founder and one of its pilots, said. The conservation group has agreed voluntarily to stop flying and has applied to FAA for a waiver. "We're considering that waiver," FAA spokesman Lynn Lunsford said. He said he didn't know when a decision would be made or whether it would be made before spring, when the birds would return to Wisconsin.