Editing Frontier Airlines (section)

== History ==
=== 1990s ===
[[File:Frontier Boeing 737-300.jpg|thumb| A Frontier [[Boeing 737 Classic#737-300|Boeing 737-300]] in the original 1994 livery. Frontier retired its last [[Boeing 737|737]] in 2005.]]
Frontier Airlines was created by Frederick W. "Rick" Brown (a [[United Airlines]] pilot), his wife Janice Brown, and Bob Schulman, the latter two having worked at the original [[Frontier Airlines (1950–1986)]].<ref name="CaptainX">{{Cite news |last=Kesmodel |first=David |title=The secret of Captain X |newspaper=[[Rocky Mountain News]] |date=February 14, 2004 |url= http://www.rockymountainnews.com/drmn/business/article/0,1299,DRMN_4_2654623,00.html |url-status=dead |archive-url= https://web.archive.org/web/20040215112344/http://www.rockymountainnews.com/drmn/business/article/0,1299,DRMN_4_2654623,00.html |archive-date= February 15, 2004 |access-date=January 26, 2020}}</ref> In 1993, [[Continental Airlines]] was scaling back flights from Denver's [[Stapleton International Airport]] (which was closed and replaced with the [[Denver International Airport]] in 1995), and the three proposed a charter airline named '''AeroDenver Travel Services''' to fill demand on international routes, potentially in partnership with [[Condor Airlines]].<ref name="CaptainX" /> To run the company, they brought in M. C. "Hank" Lund (ex-CEO of the original Frontier Airlines) as CEO and Sam Addoms as executive vice-president and treasurer (later CEO).<ref name="CaptainX" /> As Continental's Denver drawback expanded in scope in late 1993, the proposed airline pivoted to fill regional routes, and adopted the Frontier Airlines name.<ref name="CaptainX" /> The company was incorporated in February and [[went public]] in May 1994.<ref name="CaptainX" /> Scheduled flights began on July 5, 1994, using [[Boeing 737-200]] jetliners between Denver and four cities in North Dakota.<ref name="AfterMourning">{{Cite news |title=Airline Has New Frontier 8 Years After Mourning |url= https://www.deseret.com/1994/7/4/19118084/airline-has-new-frontier-8-years-after-mourning |newspaper=[[Deseret News]] |agency= [[Associated Press]] |date=July 4, 1994 |access-date=January 26, 2020}}</ref> Around three-quarters of its 180 employees, and many executives, had worked for the [[Frontier Airlines (1950–1986)|original Frontier Airlines]].<ref name="AfterMourning" /> 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.<ref name="McGill">{{cite web |url= https://www.mcgill.ca/iasl/files/iasl/aspl_614_the_new_frontier.pdf |title=The New Frontier: A Case Study |website= mcgill.ca | first=Paul Stephen |last= Dempsey |date=May 13, 2015 |access-date=January 26, 2020}}{{Self-published source|date=January 2020}}</ref> Like the original airline of the same name, the new Frontier operated a hub at Denver (DEN) and for the first nine years used the slogan "The Spirit of the West" which was displayed above the windows and just behind the cursive letters "Frontier" on the fuselage of their aircraft.

In 1999, Frontier signed agreements to begin purchasing and leasing [[Airbus]] [[Airbus A318|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 ([[Hartsfield–Jackson Atlanta International Airport|ATL]]); Baltimore ([[Baltimore/Washington International Airport|BWI]]); Bloomington/Normal, Illinois ([[Central Illinois Regional Airport|BMI]]); Boston ([[Logan International Airport|BOS]]); Chicago (MDW, [[Midway Airport]]); Dallas/Fort Worth ([[Dallas Fort Worth International Airport|DFW]]); Phoenix ([[PHX]]); Los Angeles ([[LAX]]); Minneapolis/St. Paul ([[Minneapolis–Saint Paul International Airport|MSP]]); New York City (LGA, [[LaGuardia Airport]]); Orlando ([[Orlando International Airport|MCO]]); Portland, Oregon ([[Portland International Airport|PDX]]); Salt Lake City ([[Salt Lake City International Airport|SLC]]); San Diego ([[San Diego International Airport|SAN]]); San Francisco ([[SFO]]); and Seattle ([[Seattle–Tacoma International Airport|SEA]]), all served from its Denver hub.<ref name="McGill" />

=== 2000s ===
[[File:Airbus A318-111, Frontier Airlines AN0478347.jpg|thumb|Frontier Airbus A318 in the livery introduced in 2001. Frontier was the first operator of the A318.]]
Frontier took delivery of its first Airbus aircraft (an A319) in 2001 and simultaneously launched with it [[DirecTV]] in-flight television along with a new company livery. Frontier Airlines was the launch customer of the Airbus A318 in 2003.<ref>{{cite web |title=A318 |url=https://www.airbus.com/en/who-we-are/our-history/commercial-aircraft-history/previous-generation-aircraft/a318 |access-date=October 10, 2023 |website=Airbus.com |date=June 16, 2021 |publisher=Airbus |language=en}}</ref> In mid April 2005, Frontier officially became an all-Airbus fleet, retiring its last Boeing 737.<ref>{{cite web |title=Frontier adds 38th Airbus A319 to its fleet |url= https://www.bizjournals.com/denver/stories/2005/05/02/daily26.html |website= bizjournals.com |access-date=December 18, 2019}}</ref> Jeff Potter was appointed CEO in 2002.<ref name="McGill" />

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. On April 3, 2006, Frontier created [[Frontier Airlines Holdings]] (FRNT), a [[holding company]] [[incorporated in Delaware]] to take advantage of favorable tax laws in that state. The corporate headquarters did not leave Colorado.<ref>{{cite web |url= http://www.frontierairlines.com/frontier/who-we-are/company-info/fact-sheet.do |title=Fact Sheet |date=<!--copyright 2006--> |access-date= November 1, 2006 |archive-url= https://web.archive.org/web/20061017101623/http://www.frontierairlines.com/frontier/who-we-are/company-info/fact-sheet.do |archive-date=October 17, 2006 |url-status=dead |publisher=Frontier Airlines  }}{{self-published source|date=April 2018}}</ref><!-- citation covers the full paragraph --> In 2007, Frontier established a commuter airline subsidiary, '''Lynx Aviation''', Inc., chaired by Dr. Paul Stephen Dempsey.<ref name="McGill" /> Also that year, Jeff Potter left the company and was replaced by Air Canada's Sean Menke as CEO.<ref>{{cite news |url= https://www.aviationpros.com/home/news/10386507/after-a-round-trip-that-took-him-to-air-canada-and-back-president-and-ceo-sean-menke-is-frontier-airlines-new-flying-ace|work=aviationpros|title=Jeff Potter left the company and was replaced by Air Canada's Sean Menke as CEO}}</ref>

On January 24, 2007, Frontier was designated as a [[major carrier]] by the [[United States Department of Transportation]].<ref>{{cite press release |url= http://media.frontierairlines.com/article_display.cfm?article_id=4156 |title=Frontier Airlines Offers a Major Sale From a Major Airline! |publisher=Frontier Airlines |access-date=May 17, 2012 |url-status= dead |archive-url= https://archive.today/20120709225314/http://media.frontierairlines.com/article_display.cfm?article_id=4156 |archive-date=July 9, 2012 |date=January 24, 2007 }}{{self-published source|date=April 2018}}</ref>

On January 11, 2007, Frontier Airlines signed an 11-year service agreement with [[Republic Airways]]. Under the agreement, Republic was to operate 17 76-seat [[Embraer 170]] aircraft for the former Frontier JetExpress operations. At the time the contract was canceled in April 2008, Republic Airways operated 11 aircraft for Frontier Airlines, with the remaining six aircraft expected to join the fleet by December 2008. With the integration of Republic aircraft, the 'JetExpress' denotation was removed. Subsequent to the cessation of Horizon's services for Frontier in December 2007, all flights operated by Republic were sold and marketed as "Frontier Airlines, operated by Republic Airways."<ref>{{cite news |title=Frontier Airlines signs up Republic as regional carrier |url= https://www.newspapers.com/image/539532906/?terms=Frontier%2BAirlines |access-date=January 3, 2020 |via=Newspapers.com |issue=January 12, 2007 |work=The Daily Sentinel |language=en}}</ref> The first market created specifically for the Embraer 170 was Louisville, Kentucky, which began on April 1, 2007. Service to Louisville was suspended in August 2008 but restarted in April 2010.<ref>{{cite news |title= Frontier to return with daily flight to Denver |url= https://www.newspapers.com/image/181484510/?terms=Frontier%2BAirlines%2BLouisville |access-date=January 3, 2020 |via=Newspapers.com |date= October 23, 2009 |work=The Courier-Journal |language=en}}</ref>

Flights operated by Republic Airlines offered in-flight snack and beverage services similar to Frontier's mainline flights. Unlike Frontier's aircraft and due to the nature of contracting with regional carriers, these Embraer 170 aircraft were not fitted with [[LiveTV]].<ref>{{cite news |title=Frontier Sends Roomier Jet to El Paso |url= https://www.newspapers.com/image/432663225/?terms=frontier%2Bairlines%2Bembraer%2B170%2Brepublic |access-date=December 18, 2019 |via= Newspapers.com |issue=March 7, 2007 |work=El Paso Times |language= en}}</ref>

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.<ref>{{cite news |last1=Bowley |first1= Graham |title=Frontier Airlines Files for Bankruptcy |url= https://www.nytimes.com/2008/04/12/business/12frontiercnd.html |access-date=January 28, 2020 |work=The New York Times |date=April 12, 2008}}</ref><ref>{{cite book |title=Airways: A Global Review of Commercial Flight, Volume 15 |year=2008 |publisher=Airways International, Incorporated |page=15 |url= https://books.google.com/books?id=LkYtAQAAMAAJ&q=On+April+10,+2008,+Frontier+airlines+Chapter+11+bankruptcy+first+data+ticket+sales |access-date=January 28, 2020 |language=en}}</ref> First Data decided that it would withhold 100% of the carrier's proceeds from ticket sales beginning May 1.<ref name="fstdataregrt">{{cite news| url= http://www.bizjournals.com/denver/stories/2008/04/07/daily72.html |title=First Data offers regrets about Frontier Airlines|last1= Leavitt|first1=Noelle|date=April 11, 2008|work=Denver Business Journal|access-date=April 10, 2008|last2=McGaw|first2=Renee|url-access=limited}}</ref> According to Frontier's press release, "This change in practice would have represented a material change to our cash forecasts and business plan. 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.<ref>{{cite web |date=April 11, 2008 |title=Frontier Airlines Not Grounded Yet |url=https://www.forbes.com/2008/04/11/frontier-airline-update-markets-equity-cx_mlm_0411markets24.html?sh=3c44c0beedd1 |url-status=live |archive-url=https://web.archive.org/web/20200128234134/https://www.forbes.com/topstories/2008/04/11/frontier-airline-update-markets-equity-cx_mlm_0411markets24.html/ |archive-date=January 28, 2020 |access-date=October 11, 2023 |work=[[Forbes]]}}</ref> After months of losses, Frontier Airlines reported that they made their first profit during the month of November 2008, reporting {{US$|2.9 million}} in net income for the month.<ref>{{cite news |last=Vuong |first=Andy |date=January 28, 2009 |title=Frontier reports record profit in December |work=[[The Denver Post]] |url=https://www.denverpost.com/2009/01/28/frontier-reports-record-profit-in-december/ |access-date=October 11, 2023}}</ref>

On June 22, 2009, Frontier Airlines announced that, pending bankruptcy court approval, [[Republic Airways Holdings]], the Indianapolis-based parent company of Republic Airways, would acquire all assets of Frontier for the amount of $108&nbsp;million. Thus, Frontier Airlines would become a wholly owned subsidiary of Republic.<ref>{{Cite press release|title=Republic Airways to Serve as Equity Sponsor for Frontier's Exit from Bankruptcy|date=June 22, 2009| publisher=Republic Airways Holdings| location=Indianapolis |url= http://www.republicair.com/pdf/F9.pdf|archive-url=https://web.archive.org/web/20110715173850/http://www.republicair.com/pdf/F9.pdf|archive-date=July 15, 2011}}</ref> However, five weeks later on July 30, Dallas-based [[Southwest Airlines]] announced that it would be making a competing bid of $113.6&nbsp;million for Frontier with intentions to also operate Frontier as a wholly owned subsidiary, but that it would gradually fold Frontier resources into current Southwest operating assets.<ref>{{cite news |last1=Maynard |first1=Micheline |title=Southwest Airlines Set to Make a Counteroffer for Frontier |url=https://www.nytimes.com/2009/07/31/business/31air.html |access-date=January 28, 2020 |work=The New York Times |date=July 30, 2009}}</ref>

During a bankruptcy auction on August 13, 2009, Republic Airways Holdings acquired Frontier Airlines and its regional airline, [[Lynx Aviation]], as wholly owned subsidiaries.<ref>{{cite news |last= |date=August 14, 2009 |title=Republic completes buy of Frontier Air |work=[[Reuters]] |url=https://www.reuters.com/article/us-republic-frontier-idUKTRE59048E20091001 |access-date=October 11, 2023}}</ref> On October 1, Republic completed the transaction, and Frontier officially exited bankruptcy as a new airline.<ref>{{Cite news |last= |first= |date=October 1, 2009 |title=Frontier Airlines emerges from bankruptcy |work=[[Cleveland]] |url=https://www.cleveland.com/business/2009/10/frontier_airlines_emerges_from.html |access-date=October 11, 2023}}</ref>

In late 2009, Republic began to consolidate administrative positions and moved 140 jobs from the Frontier Airlines Denver headquarters to Indianapolis.<ref>{{Cite news| url= https://www.bizjournals.com/denver/stories/2009/12/07/daily26.html| title=More Frontier Airlines jobs leaving Denver|last=Sealover|first= Ed| date=December 8, 2009|work=Denver Business Journal|access-date= April 28, 2018|url-access=limited}}</ref> Shortly after in January 2010, Republic Airways announced that it would move all of its executives to Indianapolis.<ref>{{cite news |title=Republic Airlines Moving Executives to Indianapolis |url= https://www.newspapers.com/image/310723044/?terms=Republic%2BAirways%2Bexecutives%2Bto%2BIndianapolis |access-date=January 29, 2020 |via=Newspapers.com |issue=January 15, 2010 | work=The Times |place= Munster, Indiana |language=en}}</ref> Later in February, the ''[[Denver Business Journal]]'' stated that the headquarters would be moved "soon".<ref>Harden, Mark. "[http://denver.bizjournals.com/denver/stories/2010/02/15/daily2.html DIA fare wars: Frontier Airlines offers summer discounts to 7 new destinations]." ''[[Denver Business Journal]]''. February 15, 2010. Retrieved February 17, 2010. "Frontier is a unit of Republic Airways Holdings Co., based in Indianapolis. Frontier's headquarters will be moving soon to that city."{{Registration required}}</ref> Despite this, according to the ''Denver Business Journal'', Frontier Airlines will still maintain a local headquarters in Denver to house Training, Marketing, Customer Reservations, and Scheduling & Planning teams after extending its lease on the building through 2020.{{citation needed|date = July 2017}}

In 2010, Frontier's then-CEO [[Bryan Bedford]] took part in the reality TV show ''[[Undercover Boss (American TV series)|Undercover Boss]]''.<ref>{{Cite news |last=Mandell |first=Lisa Johnson |date=October 16, 2010 |title=Frontier Airlines' Bryan Bedford: Riskiest Undercover Boss Yet |work=[[Yahoo Finance]] |url=https://finance.yahoo.com/news/2010-10-15-undercover-boss-frontier-airlines-bryan-bedford.html |access-date=October 12, 2023}}</ref>

As Republic Airways Holdings was in the process of bidding to acquire Frontier in 2009, it was also in the process of acquiring Milwaukee-based [[Midwest Airlines]]. Through the fall and winter of 2009, Republic operated its two new acquisitions as separate brands. However, to improve efficiency by better matching aircraft capacity to route demand, Republic began to intermix the fleets of the two airlines, swapping a portion of its higher-capacity planes from Frontier with its smaller-capacity planes from Midwest and vice versa. However, the move caused some confusion amongst the public, as the two brands did not offer the same amenities and did not match the amenities mentioned on the airfare. As a result, in the spring of 2010, Frontier and Midwest Airlines announced that their brands would merge, with Frontier being the surviving brand.<ref>{{cite news |last=Tabor |first=KellyHeffernan |date=April 13, 2010 |title=Midwest Airlines New Name: Frontier Airlines |work=wfmynews2.com |publisher=[[WFMY-TV]] |url=https://www.wfmynews2.com/article/news/midwest-airlines-new-name-frontier-airlines/83-401741615 |access-date=October 10, 2023}}</ref> This was a merger of brands only—no Midwest Airlines aircraft was ever operated by Frontier, as by this time, all Midwest Airlines flights were operated on its behalf by other Republic Airways Holdings subsidiaries.<ref>{{cite news |title=Republic putting on a new face |url= https://www.newspapers.com/image/126291399/?terms=Frontier%2BAirlines%2Bbrand%2Bmerger%2BMidwest |access-date=January 3, 2020 |via= Newspapers.com | work=The Indianapolis Star |date=March 21, 2010 |language=en}}</ref>

On April 13, 2011, Frontier formed a new subsidiary, '''Frontier Express''', that was planned to operate the airline's smaller aircraft with different services than those available on full-size aircraft.<ref>{{cite news |date=April 13, 2011 |title=Frontier Airlines Cuts Fee For Changing Tickets |work=[[CBS News]] |url=https://www.cbsnews.com/colorado/news/frontier-airlines-cuts-fee-for-changing-tickets/ |url-status=live |access-date=October 11, 2023 |archive-url=https://web.archive.org/web/20110418120233/http://www.cbsnews.com/stories/2011/04/13/travel/main20053727.shtml |archive-date=April 18, 2011}}</ref>

=== 2010s ===
[[File:Frontier Airlines, Airbus A320-200 N221FR ORD (30098597790).jpg|thumb|Frontier Airbus A320-200 in the 2013 livery]]
Upon the full merger and integration of Frontier and Midwest Airlines in October 2010, Frontier and its regional partners operated over 100 daily flights from the Milwaukee hub. However, on September 9, 2011, Frontier notified the public of a 40% reduction of arriving and departing flights from MKE. Along with this reduction of flights, the company laid off approximately 140 employees from the MKE station. This included but was not limited to: maintenance, grooming services, flight-line and gate.<ref>{{cite news | url= http://www.todaystmj4.com/news/local/129554838.html | title=Frontier Airlines layoffs | work=Todaystmj4.com | date=September 9, 2011 | access-date=September 9, 2011 | archive-url= https://web.archive.org/web/20120818162527/http://www.todaystmj4.com/news/local/129554838.html | archive-date=August 18, 2012 | url-status= dead }}</ref>

In February 2012, Frontier Airlines further reduced service to Milwaukee by cutting five more nonstop routes. This move "reduced Frontier's daily departing flights out of Mitchell International from 32 to 18," or 56%. 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.<ref>{{cite journal |last=Andersen |first=Mark E |date=February 17, 2012 |title=Wisconsin: The Republican 'laser focus' on jobs strikes again |url=https://www.dailykos.com/stories/2012/2/17/1064641/-Wisconsin-The-Republican-laser-focus-on-jobs-strikes-again |journal=Daily Kos Labor |archive-url=https://web.archive.org/web/20231011073029/https://www.dailykos.com/stories/2012/2/17/1064641/-Wisconsin-The-Republican-laser-focus-on-jobs-strikes-again#:~:text=Just%20over%20two%20years%20after,over%20Midwest%20Airlines%20in%202009. |archive-date=October 11, 2023 |access-date=October 10, 2023 |url-status=live }}</ref>

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.<ref name="prIndigoAcquires">{{cite news |date=February 24, 2020 |title=Frontier Airlines Check in |work= |url=https://airlinespolicy.com/check-in-policy/frontier-airlines-check-in/ |access-date=October 16, 2023}}</ref><ref>{{Cite news |date=October 1, 2013 |title=Republic Airways to sell Frontier for $145 million |work=[[Reuters]] |url=https://www.reuters.com/article/us-republic-frontier-indigo/republic-airways-to-sell-frontier-for-145-million-idUSBRE9900K520131001 |access-date=October 12, 2023}}</ref> On January 26, 2012, Republic Airways Holdings appointed former [[US Airways]] and [[Gate Gourmet]] CEO David Siegel as president and CEO of Frontier Airlines. Republic also added new senior officers for Frontier's finance and commercial team, among other changes in the executive leadership team. Siegel and other Frontier executives moved to Denver where Frontier is headquartered in order to facilitate management of all aspects of Frontier during its separation process from Republic and continue its transformation into an [[ultra low-cost carrier]] (ULCC).<ref name="phx.corporate-ir.net">{{Cite news |date=January 26, 2012 |title=Republic Airways Names New Frontier CEO, President and Interim COO |work=Business Wire |url=https://www.businesswire.com/news/home/20120126006487/en/Republic-Airways-Names-New-Frontier-CEO-President-and-Interim-COO |access-date=October 10, 2023}}</ref>

In November 2012, Frontier started low-frequency service between [[Orlando International Airport]]  and [[Trenton–Mercer Airport]] (TTN), located in [[Ewing, New Jersey]],<ref>{{Cite news |date=November 16, 2012 |title=Frontier's Trenton – Orlando Service Takes Flight |work=[[Business Wire]] |url=https://www.businesswire.com/news/home/20121116005767/en/Frontier%E2%80%99s-Trenton-%E2%80%93-Orlando-Service-Takes-Flight |url-status=live |access-date=October 12, 2023 |archive-url=https://web.archive.org/web/20141130040015/http://news.flyfrontier.com/press-release/new-cityschedule-changes/frontiers-trenton-%E2%80%93-orlando-service-takes-flight |archive-date=November 30, 2014}}</ref> which at that time, had no commercial service. Frontier later expanded service several times from Trenton, and as of January 2023 services 9 destinations.<ref>{{Cite web |title=Sitemap: City to City Flights |url=https://flights.flyfrontier.com/en/sitemap/city-to-city-flights/page-1 |access-date=January 5, 2023 |website=flights.flyfrontier.com}}</ref> Frontier currently bases three aircraft in Trenton.{{citation needed|date = July 2017}} Trenton Mercer Airport lies roughly equidistant between [[Philadelphia International Airport]] and [[Newark Liberty International Airport]].{{citation needed|date = July 2017}}

In July 2013, Frontier started service from [[Wilmington-New Castle Airport]] (ILG) near [[Wilmington, Delaware]], to five destinations,<ref>{{Cite news |date=July 1, 2013 |title=Frontier Airlines Service from Wilmington/Philadelphia Takes Flight |work=Business Wire |url=https://www.businesswire.com/news/home/20130701006293/en/Frontier-Airlines-Service-from-WilmingtonPhiladelphia-Takes-Flight |access-date=October 10, 2023 }}</ref> which Frontier markets as Wilmington/Philadelphia. Again, this airport had no commercial service prior to Frontier's entry.<ref name=tsd12820>{{cite news | title=Frontier plans to launch service from Wilmington-New Castle in mid-November | work=Delaware Business Now | date=April 21, 2020 | url= https://delawarebusinessnow.com/2020/04/frontier-plans-to-launch-service-from-wilmington-new-castle-in-mid-november/ |  access-date= May 23, 2015}}</ref> New Castle Airport lies roughly 30 miles southwest of [[Philadelphia International Airport]] and 75 miles northeast of [[Baltimore–Washington International Airport]].{{citation needed|date = July 2017}} As of 2022, Frontier does not serve ILG.<ref>{{Cite web |last=Owens |first=Jacob |date=May 13, 2022 |title=Frontier to leave Wilmington airport – again |url=https://delawarebusinesstimes.com/news/frontier-to-leave-again/ |access-date=January 5, 2023 |website=Delaware Business Times |language=en-US}}</ref>

Frontier marketed both the Trenton-Mercer and Wilmington-Philadelphia airports as low-cost, low-hassle alternatives to the existing nearby commercial airports.<ref>{{cite web |url= https://airlinefiles.com/air-wisconsin/81-national-regional-airlines/513-frontier-airlines-3.html?showall=&start=2|archive-url= https://web.archive.org/web/20220118223641/https://airlinefiles.com/air-wisconsin/81-national-regional-airlines/513-frontier-airlines-3.html?showall=&start=2|url-status= usurped|archive-date= January 18, 2022|title=Frontier Airlines Files |website=airlinefiles.com|access-date=February 4, 2020}}</ref>
Frontier is the only commercial carrier at Trenton, and was the only carrier at ILG until it left in 2022.<ref>{{cite web |url= https://www.usatoday.com/story/todayinthesky/2013/07/02/frontier-airlines-puts-delaware-back-on-usas-flight-map/2484543/ |title=Frontier Airlines puts Delaware back on USA's flight map |date=July 2, 2013 |work=[[USA Today]] |access-date=June 28, 2020}}</ref><ref>{{cite web |url=https://www.usatoday.com/story/todayinthesky/2013/11/07/has-frontier-hit-pay-dirt-at-trenton-wilmington-airports/3468101/ |title=Has Frontier hit pay dirt at Trenton, Wilmington airports?|date=November 7, 2013 |work= USA Today |access-date=June 28, 2020}}</ref>

In October 2013, Republic Airways Holdings entered into an agreement with private equity firm Indigo Partners to sell Frontier Airlines for approximately $145&nbsp;million. According to Indigo, the transaction would further Frontier's evolution into an ULCC.<ref name="prIdigoAcquires">{{cite press release |url= http://www.businesswire.com/news/home/20131203006643/en/Indigo-Partners-Completes-Acquisition-Frontier-Airlines |title=Indigo Partners Completes Acquisition Frontier Airlines |publisher=Frontier Airlines & Indigo Partners |via=Business Wire |date=December 3, 2013 |access-date=April 25, 2018 }}{{self-published source|date=April 2018}}</ref> In December 2013, Indigo Partners LLC, through an affiliate, completed the purchase of Frontier Airlines from Republic Airways Holdings. The airline's headquarters remained in Denver.<ref>{{cite news| url= http://www.denverpost.com/business/ci_24646215/sale-frontier-airlines-is-finalized | title=Frontier Airlines sale finalized to Indigo Partners LLC | work=denverpost.com | date=December 3, 2012| access-date= December 29, 2012}}</ref> On January 1, 2014, Republic Airways Holdings subsidiary Republic Airlines ceased its operation of Embraer 190 aircraft on behalf of Frontier.[[File:Frontier Airlines A321.jpg|thumb|Frontier Airbus A321-200 in the 2014 livery]]In 2014, Frontier announced it would be transitioning into an ULCC.<ref>{{cite web| url= http://www.bizjournals.com/denver/news/2015/01/19/frontier-airlines-owner-hints-at-mergers-ahead.html|title=Frontier Airlines owner hints at mergers ahead among low-cost carriers|date=January 19, 2015|work=Denver Business Journal|access-date=April 3, 2015}}</ref> Frontier also announced that it would cut several flights and jobs at its Denver hub and transition them to different markets. On January 16, 2015, Frontier announced that it would close both its Denver and Milwaukee call centers, laying off 1,300 employees and outsourcing the jobs to call center company Sitel, which operates a large call center for Frontier in [[Las Cruces, New Mexico]].<ref>{{cite web| url= http://kdvr.com/2015/01/16/frontier-airlines-to-outsource-airport-reservations-jobs-in-denver/|title=Frontier Airlines to outsource 1,160 airport, reservations jobs in Denver|work=FOX31 Denver|date=January 16, 2015|access-date=April 3, 2015}}</ref> Frontier Airlines joined Spirit and Allegiant in June 2015 by eradicating its [[toll-free telephone number]] for customer service.<ref>{{cite news| url= https://www.usatoday.com/story/travel/flights/todayinthesky/2015/08/11/frontier--latest-airline--do-away--toll-free-customer-service-number/31453053/|title=Frontier is latest airline to do away with toll-free customer service number|last=Mutzabaugh|first=Ben|date=August 11, 2015|work=USA TODAY|access-date=October 16, 2018|publisher=Gannett|quote=...discontinuing the toll-free number will save it $160,000 a month — or close to $2&nbsp;million a year.}}</ref>

In June 2014, Frontier Airlines opened a crew base for flight attendants at [[Trenton–Mercer Airport]].<ref>{{Cite news |date=February 28, 2014 |title=Frontier Airlines Announces New Crew Base to Open at Trenton-Mercer Airport |work=PR Web |url=https://www.prweb.com/releases/frontier_airlines_announces_new_crew_base_to_open_at_trenton_mercer_airport/prweb11626737.htm |url-status=live |access-date=October 11, 2023 |archive-url=https://web.archive.org/web/20140621010200/http://news.flyfrontier.com/press-release/frontier-airlines-announces-new-crew-base-open-trenton-mercer-airport |archive-date=June 21, 2014}}</ref>

In January 2015, Frontier Airlines cut several flights from Wilmington and Trenton. It also resumed service to Philadelphia, casting doubt on the airline's existing bases.<ref>{{cite web| url= http://www.nj.com/mercer/index.ssf/2015/01/frontier_airlines_officials_remain_committed_to_tr.html|title=Frontier Airlines officials remain committed to Trenton–Mercer Airport amid service cancellations|work=NJ.com|date=January 17, 2015|access-date=April 3, 2015}}</ref><ref>{{cite news | url= http://www.travelpulse.com/news/airlines/watch-what-will-frontiers-move-to-the-market-mean-for-philly-travelers.html | title=Watch: What Will Frontier's Move to the Market Mean for Philly Travelers? | first=Tim | last=Wood | work=[[TravelPulse]] | date=January 12, 2015}}</ref> In late June 2015, Frontier announced it had ceased service in Wilmington, stating it was not profitable.<ref>{{cite web| url=http://www.delawareonline.com/story/money/business/2015/06/26/frontier-airlines-officially-departs-delaware/29327411/|title=Frontier Airlines officially departs Delaware|date=June 26, 2015|work=delawareonline.com}}</ref>

In February 2015, Frontier announced that they would begin service to several destinations from [[Hartsfield–Jackson Atlanta International Airport|Atlanta]], adding the airport as a focus city. In July, Frontier began to decrease service from [[Washington Dulles International Airport]], removing the airport as a focus city. In early 2016, Frontier announced major route expansion from airports nationwide, including [[Hartsfield–Jackson Atlanta International Airport|Atlanta]], [[O'Hare International Airport|Chicago]], [[Cincinnati Northern Kentucky International Airport|Cincinnati]], [[Cleveland Hopkins International Airport|Cleveland]], [[Orlando International Airport|Orlando]], and [[Philadelphia International Airport|Philadelphia]].<ref>{{cite news|url=https://www.flyfrontier.com/plan-and-book/route-map|title= Frontier Announces Major Route Expansion|newspaper= Frontier Airlines|date=April 4, 2016}}</ref> In June 2016, Frontier re-established service to [[John Glenn Columbus International Airport]].<ref>{{cite web |last=Rose |first=Marla Matzer |date=June 1, 2016 |title=Frontier Airlines launches at Port Columbus |url=https://www.dispatch.com/story/lifestyle/travel/2016/06/01/frontier-airlines-launches-at-port/23827588007/ |access-date=October 11, 2023 |publisher=The Columbus Dispatch}}</ref> In May 2017, the airline announced it would open a new crew base in [[McCarran International Airport|Las Vegas]] in fall 2017, to improve operational reliability and potentially create new jobs in Las Vegas.<ref>{{cite web|last1=Marroquin|first1=Art|title=Frontier adding Las Vegas flights, local crew base |url= https://www.reviewjournal.com/business/tourism/frontier-adding-las-vegas-flights-local-crew-base/|website=Las Vegas Review-Journal|date=May 4, 2017|access-date=May 13, 2017}}</ref> In December 2017, Frontier began service to [[Buffalo, New York]], with service to Denver, Colorado, and Florida, including Miami, Fort Myers, Orlando, and Tampa.<ref>{{cite web |last=Peters |first=LaMonica |date=July 18, 2017 |title=Frontier Airlines offering low fares, direct flights from Buffalo |url=https://spectrumlocalnews.com/news/2017/07/18/frontier-airlines--buffalo-niagara-international-airport--buffalo--cheektowaga--airport--flight--low--fare |access-date=October 12, 2023 |website=spectrumlocalnews.com |publisher=[[Spectrum News]]}}</ref>

In May 2015, Indigo and Frontier announced the departure of David Siegel as CEO. He had already previously turned over the role of president to Barry Biffle, formerly of [[Spirit Airlines]]. Siegel was not immediately replaced; instead, his duties were split between Biffle and Indigo chairman Bill Franke. Biffle cited operational issues in connection with Siegel's departure.<ref>{{cite web| url= http://www.denverpost.com/business/ci_28107141/ceo-david-siegel-is-out-at-frontier-airlines|title=David Siegel out as Frontier Airlines CEO| first=Laura |last=Keeney |work=The Denver Post|date=May 13, 2015}}</ref>

In 2015, in an airline quality rating report by [[Embry-Riddle Aeronautical University]] and [[Wichita State University]], Frontier was ranked amongst the five worst airlines in the United States, especially due to its rate of customer complaints and bumped passengers.<ref name="Groden" /><ref>{{cite web|last1=Bowen|first1=Brent D.|last2=Headley|first2=Dean E.|date=April 13, 2015|title=Airline Quality Rating 2015|url=http://commons.erau.edu/cgi/viewcontent.cgi?article=1025&amp;context=aqrr|access-date=August 31, 2017|website=[[Embry-Riddle Aeronautical University]]}}</ref><ref>{{cite web|last=Bukszpan|first=Daniel|date=April 13, 2015|title=These are the 5 Worst Airlines in America|url=http://fortune.com/2015/04/13/five-worst-airlines-in-america/|access-date=August 31, 2017|website=[[Fortune (magazine)|Fortune]]}}</ref> The airline had relatively poor on-time performance, and the waiting time for help when calling the airline on the phone was reported to have risen to two hours or more.<ref name="FAAspike">{{cite web|last=Keeney|first=Laura|date=April 9, 2015|title=FAA records spike in consumer complaints against Frontier Airlines|url=http://www.denverpost.com/2015/04/09/faa-records-spike-in-consumer-complaints-against-frontier-airlines/|access-date=August 31, 2017|website=[[The Denver Post]]}}</ref>

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. On the weekend of December 17, the storm caused major delays at Frontier's Denver hub. The effects of the storm were felt throughout the fleet.<ref>{{Cite news |url= https://www.usatoday.com/story/travel/flights/todayinthesky/2016/12/19/frontier-airlines-apologizes-after-weather-meltdown-denver/95621028/|title=Frontier Airlines apologizes after weather 'meltdown' in Denver|newspaper=USA Today|access-date=December 24, 2016}}</ref> Flights were delayed or canceled at airports across the country; in some cases, planes were ready to depart, but the airline had no rested and available flight crews to service the flights.<ref>{{Cite news |last= |first= |date=December 20, 2016 |title=Frontier admits fault for canceled flights, lost bags |work=[[KDVR]] |url=https://kdvr.com/news/frontier-admits-fault-for-cancelled-flights-lost-bags/ |access-date=October 12, 2023 }}</ref> 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."<ref>{{Cite news |url= http://www.thedenverchannel.com/news/investigations/head-of-frontier-pilots-union-compared-airline-to-a-house-of-cards|title=Head of Frontier pilots' union compared airline to a house of cards|last= Larson| first=Jace| date=December 22, 2016|newspaper= thedenverchannel.com| language=en-US|access-date=December 24, 2016}}</ref>

=== 2020s ===

In 2020, class-action lawsuits against Frontier were filed after the company refused to refund airfare for customers who could not travel during the [[COVID-19 pandemic]].<ref>{{cite news | url=https://www.nytimes.com/2020/06/12/travel/virus-airlines-private-arbitration.html | title=In Fine Print, Airlines Make It Harder to Fight for Passenger Rights | first=SARAH | last=FIRSHEIN   | work=[[New York Times]] | date=June 12, 2020}}</ref> The company accepted part of the $25 billion in U.S. government funds to offset financial damage to the airline industry during the outbreak.<ref>{{cite news | url=https://www.nytimes.com/2020/04/14/business/coronavirus-airlines-bailout-treasury-department.html | title=Crippled Airline Industry to Get $25 Billion Bailout, Part of It as Loans
 | first= ALAN | last=RAPPEPORT   | work=[[New York Times]] | date=April 29, 2020}}</ref>

On April 1, 2021, Frontier went [[Public company|public]] with an [[initial public offering]] on the [[Nasdaq]] exchange. The company adopted the [[ticker symbol]] ULCC, a nod to the company's ultra low-cost carrier business model.<ref name="Josephs 2021">{{cite web | last=Josephs | first=Leslie | title=Frontier Airlines shares fall on first day of trading | website=CNBC | date=April 1, 2021 | url=https://www.cnbc.com/2021/04/01/frontier-airlines-raises-570-million-in-ipo-starts-trading-today.html | access-date=March 7, 2023}}</ref><ref>{{cite news | url=https://www.cnbc.com/2021/03/08/budget-airline-frontier-airlines-files-for-an-ipo-again.html | title=Budget carrier Frontier Airlines files for an IPO again| work=[[CNBC]] | date=March 8, 2021}}</ref><ref>{{cite news | url=https://www.marketwatch.com/story/frontier-ipo-prices-at-19-a-share-low-end-of-range-2021-04-01| title= Frontier IPO prices at $19 a share, low end of range | work=[[MarketWatch]] | date=April 1, 2021}}</ref>

In early 2022, Frontier attempted to acquire [[Spirit Airlines]], another US-based ULCC in a {{US$|2.8 billion}} cash-and-stock deal. The deal would have created the [[List of largest airlines in North America|fifth-largest]] airline in the country.<ref>{{cite news|last=LeBeau|first=Phil|date=February 7, 2022|title=Frontier and Spirit to merge creating fifth-largest airline in U.S.|url=https://www.cnbc.com/2022/02/07/frontier-and-spirit-to-merge-creating-5th-largest-airline-in-us.html|access-date=February 7, 2022|website=CNBC|language=en}}</ref><ref>{{Cite news|last1=Schaper|first1=David|last2=Hernandez|first2=Joe|date=February 7, 2022|title=Frontier-Spirit merger promises better deals and service; critics aren't so sure|language=en|work=NPR|url=https://www.npr.org/2022/02/07/1078842162/spirit-frontier-spirit-airlines-merger|access-date=February 9, 2022}}</ref> After announcing the proposal, [[JetBlue]] made a competing offer to acquire Spirit for {{US$|3.6 billion}} in cash. On July 27, 2022, Spirit announced that its shareholders had rejected Frontier's offer.<ref>{{Cite news |last=Chokshi |first=Niraj |date=July 27, 2022 |title=Spirit Airlines and Frontier call off a proposed merger. |language=en-US |work=[[The New York Times]] |url=https://www.nytimes.com/2022/07/27/business/spirit-airlines-frontier-jetblue.html |access-date=July 27, 2022 |issn=0362-4331}}</ref>

In November 2022, Frontier announced that it would establish a crew operating base at [[Dallas Fort Worth International Airport]] (DFW) in early 2023, and would add a gate in DFW Terminal E for flights to additional destinations starting in April of that year.<ref>{{cite news |last=Arnold |first=Kyle |date=November 3, 2022 |title=Frontier Airlines Adding Crew Base at DFW and Flights to More Destinations |work=[[NBC DFW]] |location=Dallas, Texas |url=https://www.nbcdfw.com/news/business/frontier-airlines-adding-crew-base-at-dfw-and-flights-to-more-destinations/3114233/ |access-date=October 10, 2023}}</ref> That month, it also eliminated its customer service phone line completely, referring customers to online channels.<ref>{{Cite web|url=https://www.cnn.com/2022/11/26/business/frontier-airlines-customer-service-call-center/index.html|title=Frontier Airlines no longer has a customer service phone line|work=CNN Business|first=Ramishah|last=Maruf|date=November 26, 2022}}</ref>