March 27, 2012: Flight 191 en route from New York City, to Las Vegas performed an emergency landing at Rick Husband Amarillo International Airport after the captain, Clayton Osbon, was locked out of the cockpit and subdued by passengers after he started acting erratically and ranting about terrorist. It is believed that Osbon suffered from an unspecified mental breakdown, and was treated by Northwest Texas Healthcare System. There were no fatalities.
Allegiant Air has been closely monitored by the FAA due to many emergency landings and aborted takeoffs. ABC interviewed a former Allegiant mechanic, who said "Dedicated steps were not being performed with maintenance manuals or even with general practices, before an aircraft is released." Many of these incidents had involved Allegiant's aging MD-80 aircraft, which as of November 2018 have been replaced by newer Airbus A320 family aircraft. 46 of the 86 aircraft have made emergency landings, all of which were on MD-80s. The average age of Allegiant's MD-80 fleet was 29 years compared to less than 13 years for its Airbus fleet.
jetBlue's first major advertising campaign incorporated phrases like "Unbelievable" and "We like you, too". Full-page newspaper advertisements boasted low fares, new aircraft, leather seats, spacious legroom, and a customer-service-oriented staff committed to "bringing humanity back to air travel". With a goal of raising the bar for in-flight experience, jetBlue became the first airline to offer all passengers personalized in-flight entertainment. In April 2000, flat-screen monitors installed in every seatback allow customers live access to over 20 DirecTV channels at no additional cost.
In 2007, jetBlue was also facing reliability problems with its Embraer 190 fleet. For a couple of months, jetBlue contracted ExpressJet to operate four Embraer 145 regional jets on behalf of jetBlue. While this was going on two E-190 aircraft at a time were sent to an Embraer maintenance facility in Nashville, Tennessee. ExpressJet operated routes between Boston Logan and Buffalo, New York and Washington Dulles, and between New York–JFK and Columbus, Ohio (has terminated) and Richmond, Virginia.
While its financial performance started showing signs of improvement, in February 2007, jetBlue faced a crisis, when a snowstorm hit the Northeast and Midwest, throwing the airline's operations into chaos. Because jetBlue followed the practice of never cancelling flights, it desisted from calling flights off, even when the ice storm hit and the airline was forced to keep several planes on the ground. Because of this, passengers were kept waiting at the airports for their flights to take off. In some cases, passengers who had already boarded their planes were kept waiting on the apron for several hours and were not allowed to disembark. However, after all this, the airline was eventually forced to cancel most of its flights because of prevailing weather conditions. The fiasco reportedly cost JetBlue $30 million.
It prefers to use smaller/secondary airports where landing fees cost less, such as Orlando Sanford International Airport. At Phoenix-Mesa Gateway Airport, Allegiant is now the only carrier. However, since 2015, Allegiant has been growing at major airports, such as Cincinnati, Denver, Memphis, Los Angeles, Raleigh/Durham, Indianapolis, and San Antonio.
On July 1, 2010 Allegiant returned to Long Beach Airport (LGB) in Long Beach, California having previously served LGB with DC-9 jets with nonstop flights to Las Vegas (LAS) and Lake Tahoe (TVL) in 2000. The airline also intended to fly from Bellingham International Airport and Stockton several times a week; however, there is no service at present flown between these two cities although Allegiant continues to serve Stockton with flights to Las Vegas, Phoenix/Mesa and San Diego. In November 2011, Allegiant closed its Long Beach facility and consolidated all Los Angeles area flights at Los Angeles International (LAX).
In May 2017, Allegiant Air took delivery of its first brand-new A320. Allegiant took delivery of ten new A320s in 2017 and is scheduled to accept two in 2018. All new aircraft will be painted in Allegiant's new livery at the time it is delivered. Older Airbus aircraft will be repainted during their C-checks. The new Airbus aircraft will have fuel-efficient sharklets. The new A320s seat 186 passengers, an increase of the 177 seats that are found in the rest of the Allegiant A320 fleet. To fit the additional nine seats, Allegiant opted for the Airbus Space-Flex V2 Lavatory. 
Frontier Airlines (F9) is a Denver-based low-cost carrier. The carrier flies to about 65 destinations in the United States, Costa Rica, the Dominican Republic, Jamaica and Mexico. Its fleet of planes each feature a single Economy Class cabin. However, passengers can upgrade to Select Seating, which is located toward the front of the plane, or Stretch Seating, which features more legroom. Frontier's hub is based at Denver International Airport (DEN). An additional eight airports have been designated as focus cities. The airline has a codeshare agreement with Great Lakes Airlines.
As of 2018 it ranked No. 402 financially on the Fortune 500 list of the largest United States corporations by total revenue. JetBlue Airways operates over 1,000 flights daily and serves 102 domestic and international network destinations in the U.S., Mexico, the Caribbean, Central America and South America. JetBlue is not a member of any of the three major airline alliances, but it has codeshare agreements with 21 airlines, including member airlines of oneworld, SkyTeam, Star Alliance, and unaffiliated airlines.