I'm trying to book flights to and from Europe. When a flight is listed under one airline, but says "operated by" another airline (probably a partner), which of the 2 airlines is actually providing the plane and crew? There are certain airlines whose planes and crews I definitely want to avoid, but these airlines provide the vast majority of inexpensive choices. But in every case, there is a listed airline and then an "operated by" airline.. How can I be sure I'm not flying on the "bad" airlines' planes?