Hot-pit refueling is required to operate out of locations with limited support and infrastructures.

On Sept. 14, two U.S. Air Force B-2 Spirit bombers forward deployed to Joint Base Pearl Harbor-Hickam (JBPH-H), Hawaii, conducted a routine training over the Pacific in the vicinity of Hawaii. The B-2s are deployed at JBPH-H from Whiteman Air Force Base, Missouri, in support of the U.S. Strategic Command’s Bomber Task Force. It’s the first deployment of B-2s to JBPH-H, although the aircraft are regularly rotated to the Indo-Pacific region.

During the mission, one of the the B-2s flew to Wake Island, a coral limestone atoll in the mid-pacific, east of Guam, where it conducted hot-pit refueling, a technique in which the aircraft land and refuel, without shutting down the engines.

“Hot-pit refueling allows us to maximize time in the air verses on the ground,” said Lt. Col. Nicholas Adcock, Air Force Global Strike 393rd Bomber Squadron commander in public release. “It saves turnaround time. Practicing this technique helps us ensure our effectiveness as a force and keeps us ready, capable and lethal.”

Hot-pit refueling operations are quite routine for the stealth bat-wing bombers: during long-range missions launched from Whiteman Air Force Base, Missouri, home of the 509th Bomb Wing, hot-pit refueling is also used to perform engine-running crew change activity. In the past, stealth bombers travelling to the UK (for operational purposes or to attend the airshows) have often conducted hot-pit activities on the ground, as happened during a mission to RAF Fairford in June 2015 or in July 2012 during RIAT (Royal International Air Tattoo) airshow.

Needless to say, other aircraft perform hot-pit refueling training. Among them, the U.S. Marine Corps F-35B Lightning II. For instance, F-35B STOVL belonging to Marine Fighter Attack Squadron (VMFA) 121 conducted hot pits at Marine Corps Air Station Iwakuni, Japan, in June 2017. The same squadron had started training for this kind of operation at a deployment airbase years before: on Aug. 7, 2013, two F-35B from VMFA-121 (based at MCAS Yuma back then) flew to MCAS Miramar to perform the first F-35B hot pit refuel at the airbase near San Diego, California.

 

B-2 “Spirit of Kansas” #89-0127 crashed on Feb. 23, 2008. It was the most expensive crash in USAF history.

Ten years ago, the U.S. Air Force lost one of its 21 B-2 Spirit stealth bombers.

The aircraft, #89-0127 “Spirit of Kansas”, belonging to the 393rd Bomb Squadron with the 509th Bomb Wing, from Whiteman Air Force Base, was taking off from Andersen Air Force Base, along with three other stealth bombers, at the end of 4-month deployment in support of U.S. CBP (Continuous Bomber Presence) in the Pacific. Both crew members successfully ejected from the aircraft at low altitude. The B-2 hit the ground, tumbled and burned for a total loss worth about US$1.4 billion, reportedly, the most expensive crash in the history of the U.S. Air Force.

Since take off of the aircraft was being filmed, a couple of interesting videos show the crash pretty well.

Here’s one recorded from a nearby taxiway:

Here’s a second video, seemingly filmed from Guam’s control tower:

The investigation found out that the root cause of the accident was moisture in the air-data sensors: heavy, lashing rains caused moisture to enter skin-flush air-data sensors that gave wrong inputs to the flight-control computers. The combination of slow lift-off speed and the extreme angle of attack resulted in an unrecoverable stall, yaw, and descent.

Here’s what the U.S. Air Force website reported after the report was released:

Moisture in the aircraft’s Port Transducer Units during air data calibration distorted the information in the bomber’s air data system, causing the flight control computers to calculate an inaccurate airspeed and a negative angle of attack upon takeoff. According to the report, this caused an, “uncommanded 30 degree nose-high pitch-up on takeoff, causing the aircraft to stall and its subsequent crash.”

Moisture in the PTUs, inaccurate airspeed, a negative AOA calculation and low altitude/low airspeed are substantially contributing factors in this mishap. Another substantially contributing factor was the ineffective communication of critical information regarding a suggested technique of turning on pitot heat in order to remove moisture from the PTUs prior to performing an air data calibration.

The pilot received minor injuries, and the co-pilot received a spinal compression fracture during ejection. He was treated at Tripler Army Medical Center, Hawaii, and released. The aircraft was assigned to the 509th Bomb Wing at Whiteman Air Force Base, Mo.

At the time of the crash, the B-2 had logged 5,100 flight hours and wasn’t carrying armament.