The Sikorsky MH-53 Pave Low series is a retired long-range special operations and combat search and rescue (CSAR) helicopter for the United States Air Force.

[1] The US Air Force ordered 72 HH-53B and HH-53C variants for Search and Rescue units during the Vietnam War, and later developed the MH-53J Pave Low version for Special Operations missions.

The Pave Low's mission was low-level, long-range, undetected penetration into denied areas, day or night, in adverse weather, for infiltration, exfiltration and resupply of special operations forces.

This name is a reference to the smaller HH-3E "Jolly Green Giant", a stretched variant of the H-3 Sea King, used in the Vietnam War for combat search-and-rescue (CSAR) operations.

The US Air Force regarded their Sikorsky S-61R/HH-3E "Jolly Green Giant" long-range CSAR helicopters favorably and was interested in the more capable S-65/CH-53A.

[6] The HH-53B was essentially an interim type, with production quickly moving on to the modestly improved Air Force HH-53C CSAR variant.

Other changes included more armor and a more comprehensive suite of radios to improve communications with C-130 tankers, attack aircraft supporting CSAR actions, and aircrews awaiting rescue on the ground.

A limited night / foul weather sensor system designated "Pave Low I" based on a low-light-level TV (LLLTV) imager was deployed to Southeast Asia in 1969 and combat-evaluated on a Super Jolly, but reliability was not adequate.

This exercise proved much more satisfactory, and so eight HH-53Cs were given a further improved systems fit and redesignated HH-53H Pave Low III, with the YHH-53H also upgraded to this specification.

In 1986, the surviving HH-53Hs were given an upgrade under the CONSTANT GREEN program, featuring incremental improvements such as a cockpit with blue-green lighting compatible with night vision goggles (NVGs).

There were some avionics upgrades as well, including fit of a modern Global Positioning System (GPS) satellite navigation receiver.

Low-level penetration was made possible by a state-of-the-art terrain following radar, as well as infrared sensors that allow the helicopter to operate in bad weather.

The MH-53M Pave Low IV was modified from the MH-53J configuration with the addition of Interactive Defensive Avionics System/Multi-Mission Advanced Tactical Terminal or IDAS/MATT.

During the operation, MH-53Js conducted missions including reconnaissance, small team insertion, medivac, logistics, and fire support.

[7] The MH-53 Pave Low's last mission was on 27 September 2008, when the remaining six helicopters flew in support of special operations forces in Southwest Asia.