Lockheed C-130 Hercules L-100

The Lockheed L-100 Hercules is the civilian variant of the C-130 Hercules military transport aircraft. It can be told at a glance from the military C-130 and C-130J by the absence of the side and forward windows underneath the main windshield.

Its origins lie in several earlier attempts to take the Hercules to the commercial market. In 1959 Pan American World Airways ordered twelve of Lockheed's GL-207 Super Hercules for delivery by 1962, to be powered by four 6,000 eshp Allison T56 turboprops, but never took delivery; Slick Airways was to receive six more later that year. The Super Hercules would have been 23 ft 4 in (7.11 m) longer than the C-130B, and a version powered by 6,445 eshp Rolls-Royce Tynes and a jet-powered variant with four Pratt & Whitney JT3D-11 turbofans were also studied. In 1960 Zantop Air Transport won a USAF Logair domestic cargo contract for bulky freight by agreeing to purchase five C-130Bs that Lockheed would certificate commercially, but the agreement foundered when the two parties failed to agree on financing terms.

The L-100 prototype, registered N1130E, finally flew on 20 April 1964, carrying out a 25-hour, one-minute flight, the longest first flight of a commercial aircraft at the time. The type certificate was awarded on 16 February 1965 and twenty-one production aircraft were built, the first delivered on 30 September 1965 to Continental Air Services, a wholly owned subsidiary of Continental Airlines. The stretched L-100-30 version was certificated in October 1970, and Lockheed rebuilt some L-100-20s to L-100-30 standard.

A prominent user was Interior Airways, an Alaska bush operator, and its corporate successor Alaska International Air, which used the aircraft to fly to short gravel or snow and ice runways in the far north of the state. In the 1970s AIA was a pure L-100 operator, flying both within Alaska and globally, and for regulatory reasons held an effective monopoly on the use of the type in support of the Alaska pipeline construction. When pipeline construction was unexpectedly delayed, Red Dodge Aviation, a local competitor established for that purpose, went out of business, while Alaska Airlines, the pioneering civilian operator of the L-100, exited the business in the early 1970s. In 1974 AIA crashed an L-100 on Fletcher's Ice Island, a massive iceberg floating in the Arctic Ocean that hosted a Navy station complete with runway: the aircraft was a write-off, but a team of AIA mechanics rebuilt it on site in the open over six months, including the installation of a whole new wing, and it returned to Alaska in stages and re-entered service.

Another substantial group of users in the 1970s and 1980s were the civilian contractors of the U.S. military's domestic air cargo networks, Logair for the Air Force and Quicktrans for the Navy, among them Airlift International, Saturn Airways, Trans International Airlines and Southern Air Transport. During the 1970s Quicktrans transitioned entirely to the L-100, which remained its sole type until the programme ended in 1994; within Logair the L-100 was used from the late 1960s until the programme ended in 1992. The largest L-100 operator in the world was often whichever airline held the Logair or Quicktrans contract at the time. Delta Air Lines operated several L-100-20s on scheduled freight flights between 1968 and 1973. Deliveries totalled 114 aircraft and production ended in 1992.

An updated civilian version of the C-130J-30 Super Hercules was under development but was placed on hold indefinitely in 2000 to focus on military development and production. On 3 February 2014 Lockheed Martin formally relaunched the programme as the LM-100J, saying it expected to sell 75 aircraft and presenting it as the natural replacement for the existing civil L-100 fleets. The LM-100J completed its first flight at Marietta, Georgia, on 25 May 2017 and entered series production in 2019.