I think the airline would normally send the crew on the next available passenger flight to the said airport, or an airport close by then a taxi ride to the airport. I've never heard of a flight positioning out empty to drop off crew, but I would guess it's probably happened before! Never heard of airlines chartering business jets etc for crew, but maybe that's happened too. I think I'm right in thinking Jet2 (or Dart Group?) own a PA31 which shuttles crew around the UK.