An investigation has been launched into possible conspiracy in the airline industry. The government has to show that different airlines were indicating about their business decisions in order to drive up fares.

The investigation is in its initial phase. This week, letters have been sent to American Airlines, Delta Air Lines, Southwest Airlines and United Airlines. All the four of them control over 80% of the domestic seats on planes.

It is being said that airlines cannot reveal about pricing decisions. General trend is airlines increase flights as per demand. If there is more demand then there will be more flights and sometimes, routes have to be cut because of not enough demand. There is nothing wrong with it. But the problem arises when airlines group together to limit flights to increase fares.

Now, it has been seen in past few years that airline executives and Wall Street analysts have opened a lot about discussing about airline's passenger capacity in check. This capacity talks now not only have led to more booked flights, but higher ticket price as well.

Now, the questions that arise are, were airlines answering to Wall Street's questions about capacity generally or they were illegally indicating not to compete sternly to raise more profits.

The Justice Department has been looking out for all the possible clues, including communications and other signals that may reveal about something wrong. It would be too early to say where the investigation is going.

If the evidence is found then it could lead to a consent decree as per which, the airlines will have to be from doing certain behaviour, like issuing public statements about their intentions with regard to capacity.