[23] By January 1995, Frontier had expanded its route network from Denver and was serving destinations in New Mexico, Montana, North Dakota, Texas, Nevada, Nebraska, and Arizona.

In 1999, Frontier signed agreements to begin purchasing and leasing Airbus A318 and A319 jet aircraft and had also added Boeing 737-300 jetliners to its fleet as well.

Also by September 1999, the airline was serving destinations from coast to coast in the U.S., having expanded its route network to include Atlanta (ATL); Baltimore (BWI); Bloomington/Normal, Illinois (BMI); Boston (BOS); Chicago (MDW, Midway Airport); Dallas/Fort Worth (DFW); Phoenix (PHX); Los Angeles (LAX); Minneapolis/St.

[24] As part of its plan to stay competitive in reaction to the entry of Southwest Airlines into Denver, the company underwent a reorganization early in 2006.

[32] On April 10, 2008, Frontier filed for Chapter 11 bankruptcy in reaction to the intent of its credit card processor, First Data, to withhold significant proceeds from ticket sales.

Unchecked, it would have put severe restraints on Frontier's liquidity..." Its operation continued uninterrupted, though, as Chapter 11 bankruptcy protected the corporation's assets and allowed restructuring to ensure long-term viability.

[41] In late 2009, Republic began to consolidate administrative positions and moved 140 jobs from the Frontier Airlines Denver headquarters to Indianapolis.

[citation needed] In 2010, Frontier's then-CEO Bryan Bedford took part in the reality TV show Undercover Boss.

Frontier announced further layoffs in conjunction with this route change: up to 446 Milwaukee-area employees were affected by the job cuts that occurred between April 15 and 30, 2012.

[50] In an effort to focus on regional contract flights for major carriers, Republic Airways Holdings announced in January 2012 its intention to sell or spin off Frontier.

In October 2013, Republic Airways Holdings entered into an agreement with private equity firm Indigo Partners to sell Frontier Airlines for approximately $145 million.

[62] In December 2013, Indigo Partners LLC, through an affiliate, completed the purchase of Frontier Airlines from Republic Airways Holdings.

[65] Frontier Airlines joined Spirit and Allegiant in June 2015 by eradicating its toll-free telephone number for customer service.

[70] In February 2015, Frontier announced that they would begin service to several destinations from Atlanta, adding the airport as a focus city.

In early 2016, Frontier announced major route expansion from airports nationwide, including Atlanta, Chicago, Cincinnati, Cleveland, Orlando, and Philadelphia.

[79] In December 2016, a winter weather event disrupted fleet operations and caused Frontier to delay or cancel up to 70% of their flights suddenly during the peak of the crisis.

[81] The head of Frontier's pilot's union issued a statement criticizing the companies' handling of the event, comparing the airline to a "house of cards.

[83] The company accepted part of the $25 billion in U.S. government funds to offset financial damage to the airline industry during the outbreak.

[103] Siegel's tenure ran through May 2015, when he left for personal reasons and was succeeded by the company's chairman, Bill Franke, who would manage strategy and finances.

As the service by Horizon Air was winding down in November 2007, Frontier had some flights operated by ExpressJet using Embraer-145 regional jets.

On September 6, 2006, Frontier created a new division of the holding company, known as Lynx Aviation, to operate Bombardier Q400 aircraft beginning in May 2007.

In early 1997, Maverick Airways was operating codeshare service for Frontier with de Havilland Canada DHC-7 Dash 7 STOL capable turboprops between Denver (DEN) and two destinations in Colorado: Grand Junction (GJT) and Steamboat Springs (SBS).

From 1994 to 2001, the airline's livery consisted of green script "Frontier" titles on the forward fuselage, a small "Spirit of the West" slogan, and wildlife photography on the tail of each aircraft.

New additions are Penguins Jim, Joe, Jay, and Gary, a barbershop-style quartet, singing the praises of EarlyReturns to an audience of Frontier's well-known characters from the "a whole different animal" campaign, Hector the otter, advertising Frontier's expanding service to Mexico, and Polly the Parrot, who won the new animal audition in 2012.

Expanding on these concepts in 2023, Frontier introduced a new approach with their animal mascots taking on promiscuous roles in a calendar titled "Fur & Feathers".

[113] Frontier Airlines operates a network consisting of both domestic and international destinations in the United States, Mexico, Central America, and the Caribbean.

[citation needed] As an ultra low-cost carrier (ULCC), Frontier imposes fees for additional amenities and services, such as for advance seat reservation and baggage allowance, the waiving of fees associated with changing or cancelling itineraries, and operates a buy on board service for in-flight catering.

Prior to its transition to an ULCC, the airline offered DirecTV channels on seat-mounted electronic screens for an additional fee.

[134][135] The program has four tiers of elevated frequent flyer status, consisting of Elite Silver, Gold, Platinum, and Diamond.

Elite benefits progressively include more and more complimentary services and amenities, such as advance seat assignments, baggage allowance, or priority boarding.