large jets. In addition, US Airways Express operators offer complementary service in our existing mainline markets by operating flights during off-peak periods between mainline flights. During 2010, the US Airways Express network served 155 airports in the continental United States, Canada and Mexico, including 75 airports also served by our mainline operation. During 2010, approximately 28 million passengers boarded US Airways Express air carriers’ planes, approximately 44% of whom connected to or from our mainline flights. Of these 28 million passengers, approximately 8 million were enplaned by our wholly owned regional airlines Piedmont and PSA, approximately 20 million were enplaned by third-party carriers operating under capacity purchase agreements and less than 1 million were enplaned by carriers operating under prorate agreements, as described below. The US Airways Express code share arrangements are in the form of either capacity purchase or prorate agreements. The capacity purchase agreements provide that all revenues, including passenger, mail and freight revenues, go to us. In return, we agree to pay predetermined fees to these airlines for operating an agreed-upon number of aircraft, without regard to the number of passengers on board. In addition, these agreements provide that certain variable costs, such as airport landing fees and passenger liability insurance, will be reimbursed 100% by us. We control marketing, scheduling, ticketing, pricing and seat inventories. Under the prorate agreements, the prorate carriers receive a prorated share of ticket revenue and pay certain service fees to us. The prorate carrier is responsible for pricing the local, point to point markets to the extent that we do not have competing existing service in that market. We are responsible for pricing all other prorate carrier tickets. The prorate carrier is also responsible for all costs incurred operating the aircraft. Our prorate carriers, Colgan Air, Inc. and Trans States Airlines, Inc., operated 10 turboprops and three regional jets, respectively, at December 31, 2010. All US Airways Express carriers have logos, service marks, aircraft paint schemes and uniforms similar to our mainline operation. In January 2010, Mesa Air Group, Inc. and certain of its subsidiaries, including Mesa Airlines, Inc. (“Mesa”), filed voluntary petitions for relief under Chapter 11 of the U.S. Bankruptcy Code. At December 31, 2010, Mesa operated 51 aircraft for our Express passenger operations, representing over $500 million in annual passenger revenues to us in 2010. In November 2010, we signed an agreement for an extension of 39 months on average from the current scheduled expiration of June 30, 2012, for the operation of 38 CRJ900 aircraft by Mesa under the companies’ codeshare and revenue sharing agreement, which agreement was approved by the U.S. Bankruptcy Court. The remaining 13 aircraft were not extended. On January 20, 2011, the U.S. Bankruptcy Court approved the bankruptcy plan of Mesa Air Group, Inc., who is expected to emerge from bankruptcy on or about February 28, 2011. For more discussion, see Part 1, Item 1A, “Risk Factors – If we incur problems with any of our third-party regional operators or third-party service providers, our operations could be adversely affected by a resulting decline in revenue or negative public perception about our services.” The following table sets forth our US Airways Express capacity purchase agreements and the number and type of aircraft operated under those agreements at December 31, 2010. Number and Type Carrier of Aircraft PSA(1).................................................. 49regional jets Piedmont (1) ............................................... 44turboprops Air Wisconsin Airlines Corporation .............................. 70regional jets Republic Airline Inc. ........................................ 58regional jets Mesa Airlines, Inc. .......................................... 45regional jets and 6 turboprops Chautauqua Airlines, Inc. ..................................... 9regional jets (1) PSA and Piedmont are wholly owned subsidiaries of US Airways Group. Marketing and Alliance Agreements with Other Airlines We maintain alliance agreements with several leading domestic and international carriers to give customers a greater choice of destinations. Airline alliance agreements provide an array of benefits that vary by partner. By code sharing, each airline is able to offer additional destinations to its customers under its flight designator code without materially increasing operating expenses and capital expenditures. Through frequent flyer arrangements, members are provided with extended networks for earning and redeeming miles on partner carriers. US Airways Club 7.