Philadelphia, PA –

U.S. Airways has published its ticket rates and some routes like the Pittsburgh to Philadelphia will rise 600%, from $118 to $698 starting in January.

The price increase comes as Southwest Airlines is pulling out of the same route.

U.S. Senator Bob Casey has sent a letter to the airline asking for an explanation and U.S. Airways replied they price their tickets based on what the market will bear.

However shocking this may seem, it’s not the first time and is not unusual. Typically when a low-cost carrier, enters a market, ticket prices drop across all competitors, and when a low-cost carrier pulls out of a market, ticket prices rise again. It’s part of what is called the “Southwest Effect” now taught at most colleges in business classes.

Sen. Casey says the fare hike would have a detrimental impact on businesses and individuals, the paper reports.

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