Spirit, which mainly operates on domestic routes, also forecast weaker-than-expected revenue for the third quarter, with Citi analysts citing the effect from travel demand shifting to international from domestic.
The airline, which also missed second-quarter profit and revenue estimates, has also struggled with pilot attrition and geared turbofan engine issues.
Its shares fell 5.7% in morning trade as current-quarter revenue forecast of between $1.30 billion and $1.32 billion came in below expectations of $1.51 billion, as per Refinitiv data.
Last week, Southwest Airlines and Alaska Air had offered downbeat full-year forecasts.
Shares of large U.S. airlines Delta Air Lines, United Airlines and American Airlines slipped about 1%, while Southwest fell about 2%.
Adding to the gloom, online travel firm Expedia Inc reported smaller-than-expected bookings for the second quarter, even as it said travel demand remained "strong."
Gross bookings of $27.32 billion missed analysts' estimates of $28.16 billion.
Revenue from points of sale in the U.S. fell to $2.17 billion from $2.21 billion, while international sales rose.
"We believe this is further evidence of softening in U.S. travel demand trends while international growth continues to outperform," Wedbush analyst Scott Devitt said in a note.
U.S. domestic airfares had seen some declines as capacity increases, company executives said during an investor call, while cross-border airfares were stable.
Expedia's shares plunged 14% to $101.29.
The company reported an adjusted profit of $2.89 per share, beating expectations of $2.32 but revenue of $3.36 billion was slightly below expectations.
Tripadvisor and Trivago's U.S-listed shares were down 8.6% and 3.3%, respectively.
Shares of vacation rental firm Airbnb, which reports results later on Thursday, were down 1.5%.
(Reporting by Priyamvada C, Kannaki Deka, Pratyush Thakur in Bengaluru; Editing by Sriraj Kalluvila)