In this articleSAVEULCCJBLUJetBlue Airways, Spirit Airlines and United Airlines airplanes proceed to gates after landing at Newark Liberty International Airport in Newark, New Jersey on May 30, 2024.Gary Hershorn | Corbis News | Getty ImagesAirlines that spent years clamoring for new jets are changing their tune.Cash-strapped, low-cost and deep discounter airlines are putting off spending billions of dollars on new aircraft to save money as they try to return to steady profitability and face the impact of e ...