Editing ETOPS (section)

=== Early jet airliners ===
While the earliest jet engines were sometimes unreliable, widespread use of later engines such as the [[Pratt & Whitney JT8D]] (e.g. [[McDonnell Douglas DC-9]] and [[Boeing 737]]) led to major advances in reliability and safety. As jet engines started to deliver more power than piston engines while increasing reliability, aircraft whose size previously required four piston engines could now be built using only two jet engines.<ref name=AirbusETOPS/>{{rp|p=p.11}}

By the late 1960s, most large civil airliners were jet-powered, relegating the piston engine to roles such as cargo flights. With the JT8D reliably powering the three-engine [[Boeing 727]], the 60-minute rule was waived in 1964 for three-engine aircraft, which in turn opened the way for the development of [[wide-body aircraft|wide-body]], intercontinental [[trijet]]s such as the [[Lockheed L-1011 TriStar]] and [[McDonnell Douglas DC-10]]. By then, only twin-engine jets were restricted by the 60-minute rule. Trijets and quadjets dominated international long-haul flights until the late 1980s.