Prof Vikrant Vaze

"While air service has increased and prices have dropped at large airports over the past 15 years," writes Travel Weekly, "the picture has been more mixed for medium-size airports, according to a recent analysis by the Eno Center for Transportation. ...

... "In its own summation, the Eno Center noted that more research needs to be done to understand the trends that affect air service in individual metropolitan areas. The economic crash of 2008, low fuel prices, a nationwide regional airline pilot shortage and consolidation have all impacted the U.S. airline industry over the past decade.

"One person who has delved deeper into the impact that consolidation, in particular, has had on airline service across the U.S. is Dartmouth's Vaze.

"In a peer-reviewed study titled 'Impact of airline mergers on passenger welfare,' which was published in May by the journal Transportation Research, Vaze and two other scientists used a mathematical formula to assess the impact that each of the five major airline mergers between 2005 and 2013 have had on passengers.

"Included in the measure of passenger welfare were such factors as prices, flight frequencies, the number of nonstop and one-stop markets served and the time it takes to complete itineraries.

"The researchers found that the Delta-Northwest merger of 2008 and the United-Continental merger of 2010 had an overall positive impact on U.S. flyers, while the 2005 US Airways-America West merger, the 2011 Southwest-AirTran merger and the 2013 American-US Airways merger were neutral for consumers.

"More significant than the nationwide findings, though, were regional trends, Vaze said. The researchers found that after a merger, the passengers in the home region of the surviving carrier see gains in passenger welfare, while those in the region where the subsumed carrier had its larger network either gain less or lose."