It really is a simple question. The only thing that is specific would be the company actually flying the aircraft. It's all based on CASM and RASM. That will give you the break even load factor. Doesn't matter what people pay for the flight. It's all about what the flight costs. For example it you take a jetBlue A320 it's CASM from what I remember is around 8-9 cents. That is how much it costs to fly one seat one mile on average. So it costs the company roughly $90 to move one seat a thousand miles. Mulitply that times 154 and you get about $14000. That's what it costs the carrier to fly that aircraft 1000 miles. All factors are included in that cost. As you can see, profit margins are not that great since they don't charge very much for tickets.