The airport director in Worcester, Massachusetts, felt that Allegiant reneged on a commitment to serve the airport for five years given the use of federal grants to assist its startup. However, the airline responded that the market was immediately unprofitable and starting service there was a poor decision; flights were reported to be 80% full.[51] Allegiant's flights average 90% full.[42]
In 2011, JetBlue made interline agreements with Virgin Atlantic and Jet Airways, both of which have since been terminated.[112][113] Since 2012, JetBlue has had an interlining agreement with Air China. It also established an interline agreement with Porter Airlines connecting from Billy Bishop Toronto City Airport to US destinations through Boston and Newark.[114]

In March 2010, Allegiant purchased six used Boeing 757-200 jetliners as part of plans to begin flights to Hawaii, with deliveries from early 2010 to the fourth quarter of 2011.[25] It gained the approval for type with the FAA in July 2011,[26] and then worked with the FAA to obtain the appropriate ETOPS rating in order to be able to serve Hawaii. Allegiant no longer operates nonstop service to Honolulu from Las Vegas.[27]
The initial JetExpress partnership with Mesa ended in January 2004, when Horizon Air was selected to operate the routes. Horizon utilized slightly larger CRJ-700 regional jet aircraft on these routes. In August 2006, Frontier and Horizon ended their partnership.[64] While Frontier was generally pleased with Horizon's operation, the carrier decided that it needed to revisit the agreement and find a provider with additional regional jets to grow the operation. The last of the CRJ-700's was returned to the Horizon Air fleet on November 30, 2007.