United still flies its 27-year-old Boeing 737

United Airlines' oldest Boeing 737, a 27-year-old 737-700, remains in active service, highlighting the longevity of the aircraft. The airline has over 25 of these planes older than 25 years. The aircraft, originally delivered to Continental Airlines in 1998, continues to operate domestic and short-haul flights. These older 737-700s are slated for replacement by newer 737 MAX 8 and MAX 10 models. United's fleet modernization plan aims to replace aging aircraft with more fuel-efficient models, improving the passenger experience. The phase-out of the 737-700s is expected by the end of the decade.