The airline industry is arguably an oligopoly

The airline industry is arguably an oligopoly. There are 4 major domestic airlines which operate about 80% of all domestic flights. Assume that these companies decided to divide the market and reached an agreement/formed a cartel. Indicate what quantity and price they would try to set and contrast it to the quantity and price of a competitive market. Do you think that these airlines could stay together in the agreement over the long term? Discuss possible reasons of why their agreement could be not successful or, why do you think airlines could be able to beat the odds and continue to collude?