MH-53 PAVE LOW History

“The idea of a vehicle that could lift itself vertically from the ground and hover motionless in the air was probably born at the same time that man first dreamed of flying.”
– Igor Ivanovich Sikorsky

The MH-53M PAVE LOW IV was retired in September 2008 in Iraq upon flying its last mission in combat. This was the only way to retire an aircraft that had been flying in the USAF inventory since the Vietnam War in the late 1960’s.  The name PAVE LOW was a code name assigned to a project specifying modification to the HH-53, which stemmed from a requirement to operate the helicopter at night and in adverse weather in order to be more effective against enemy forces.  In order to understand her history, it’s important to start from the very beginning.

The Sikorsky CH-53A (S-65) was ordered in 1962 to satisfy a Marine Corps requirement for a heavy-lift helicopter. The first aircraft (YCH-53) flew either 12 or 14 October, 1964. It would be replaced by the CH-53D.

The U.S. Air Force H-53 began its legacy in late 1967 during the Vietnam War as the HH-53B Super Jolly Green Giant, created as the finest combat search and rescue helicopter in the world. A total of 72 HH-53B and HH-53C helicopter variants were ordered by the USAF. During the H-53’s first three years of service between 1967 and 1970 it was credited with over 371 combat rescues.

In 1968, eight HH-53 B/Cs received the first of several modifications, called Limited Night Recovery System (LNRS), which incorporated a low light TV and a hover coupler. The B-model was an A-model airframe, which Sikorsky separated into three sections to add supports (struts) for the auxiliary fuel tanks. The tanks were needed to increase the range of the HH-53 for CSAR duties in Vietnam.

The HH-53B featured:

  • A retractable in-flight refueling probe.
  • Jettisonable external auxiliary fuel tanks with a capacity of 650 gallons, fitted to the sponsons and braced by struts attached to the fuselage.
  • A rescue hoist above the right passenger door, capable of deploying a forest penetrator on 250' of steel cable.
  • Armament of three pintle-mounted General Electric GAU-2/A 7.62 mm (.308 in) six-barreled Gatling-type machine guns, two mounted up front in left window and right door, and one on the tail ramp.
  • A total of 1,200 pounds of armor.
  • A Doppler navigation radar.

Early HH-53Bs featured T64-GE-3 engines with 3,080 shaft horsepower each. These engines were later upgraded to T64-GE-7 with 3,925 shaft horsepower. Standard aircrew included a pilot, copilot, crew chief, and two pararescuemen.

The C-model airframes already incorporated support for the aux tanks. As the Jolly Greens were conducting rescue missions in theater, the catalyst for the development of Special Operations Helicopters occurred to Air Force aircrews in Laos, Cambodia and Vietnam.

In July 1970, the USAF requested the need for an integrated system on their HH-53s to enable the rescue platform to perform search and rescue under conditions of total darkness and/or adverse weather in all geographical areas, including mountainous terrain, low level altitude, and capable of penetrating hostile territory.

In April 1974, the HH-53 modification program was signed and incorporated a radar with terrain following/avoidance avionics called "PAVE LOW III".

The original eight HH-53H’s were the very first U.S. Air Force helicopters modified to become the MH-53J PAVE LOW III. All remaining H-53 B, C, and H models were then modified to the MH-53J model standard. The airframes rolled out in the late 70’s and had the same basic radar, but very different avionics. The J-model PAVE LOW solved many H model problems and provided improved avionics. The only external difference between an early J model and the H model PAVE is the IRCM pod on the sponsons. The H-model PAVE LOW had a long tube like device for IRCM capabilities. The Air Force never flew the H model PAVE LOWs in combat.

On 5 December 1974 Sikorsky delivered the last HH-53 to the Air Force.

On June 9th, 1975 the first HH-53H PAVE LOW, tail number 66-14433, flew its first flight. The flight was originally scheduled for June 6th, but ground abort due to an error in the fuel jettison system.

Under the PAVE LOW III program, the U.S. Air Force NAVAIR 26BFTG, dated 18 Nov 1976, called for the “PAVE LOW III” modification to nine MH-53H aircraft between Sep 1978 and Jan 1980 (the remaining 32 HH-53s soon followed) for night and adverse weather operations. Modifications included forward-looking infrared, inertial global positioning system, Doppler navigation systems, terrain-following and terrain-avoidance radar, an on-board computer, and integrated avionics to enable precise navigation to and from target areas.

The Air Force designated these modified versions as MH-53J’s. The 32 HH-53s that followed created a total of 41 MH-53J PAVE LOW III helicopters. The PAVE LOW III concept was expedited from the unfortunate lessons of Operation EAGLE CLAW in 1979 (aka Desert One), where the PAVE LOW would have been the clear choice of aircraft, but was just leaving the production line.

In 1999, the MH-53J was modified to unofficially become the MH-53M PAVE LOW IV, officially it was designated the MH-53J PAVE LOW IIIE due to "political" reasons with the U.S. Army 160th SOAR.

The Rescue and Special Operations H-53 aircraft and personnel led the way for over 41 years, standing up to fight “Any Time, Any Place”. The PAVE LOW creed lives on in the Special Operator aircrews of past who garnished the “Red Scarf”, a brotherhood whose life is the mission and the security of our nation.

Other Historical Facts:

PAVE LOW I (YH-53 / HH 66-14433) – The first aircraft to be fitted with PAVE LOW I trials for a projected night/all-weather combat rescue/infiltration mission. Fitted with early low-light TV system which proved inadequate, though the first successful night rescue was made with an improved system in December 1972, in Laos. The aircraft later modified to ‘PAVE LOW II’ standard, with external sponsons and tanks.

PAVE STAR – Modification of HH-53C for night/adverse weather operations

PAVE IMP – An Air Force night vision program under which HH-53Cs were equipped with low-light-level television (LLLTV) cameras, providing the aircraft with the all-weather capability to rescue downed airmen. The program replaced the service’s PAVE STAR program.

CONSTANT GREEN – MH-53H PAVE LOW upgrade program

PAVE LOW – Modification of HH-53B for night/adverse weather operations: AN/APQ-141; AN/APQ-126B, AN/APQ-158, AN/AAQ-10

PAVE LOW II – One HH-53C converted to YH-53H, eight plus two HH-53G converted to HH-53H, MH-53H PAVE LOW, 1975, 1979/1980. Remaining 31 HH-53B/C to MH-53J PAVE LOW IIIE (E = Enhanced), 1985