Defense

March 17, 2014

Investigation board determines cause of KC-135 crash in May

The U.S. Air ForceAir Mobility Command has released the results of an accident investigation that examined what caused the May 3, 2013, crash of a KC-135 Stratotanker in the Kyrgyz Republic.

The crew of three, en route from the Transit Center at Manas to Afghanistan on a combat aerial refueling mission, perished in the mishap.

Upon takeoff, a flight control system malfunction, the board found, generated directional instability, causing the aircraft’s nose to slowly drift from side-to-side or “rudder-hunt.” This condition, not fully diagnosed by the crew, progressed into a more dangerous oscillatory instability known as a “Dutch roll.” The board identified that a poor layout of key information in the inflight manual and insufficient crew training contributed to the mishap by detracting from the crew’s ability to act on critical information during their troubleshooting to turn off either of two cockpit switches which may have eliminated the malfunction.

Having not recognized the Dutch roll condition, the crew initiated a left turn to remain on-course along the planned route of flight and used a small amount of left rudder to coordinate the turn. The use of rudder, while in a Dutch roll, increased the aircraft’s oscillatory instability. The ensuing large side-to-side movements of the aircraft varied the crew member’s foot pressure on the rudder pedal which caused inadvertent fluctuations in rudder position. These fluctuating rudder movements, coupled with slight right rudder use while rolling out of the turn, compounded the Dutch roll severity and produced extreme airframe stress that caused the KC-135’s tail section to separate from the aircraft. The subsequent, uncontrollable descent resulted in an in-flight explosion.

“Our hearts go out to the family members and friends of these Airmen,” said Brig. Gen. Steve Arquiette, who led the accident investigation board. “Having attended the memorial service at Manas and later interviewing many co-workers, I know these Airmen were highly regarded and are greatly missed. The investigation team, with the help of our industry and Kyrgyz government partners, pushed through months of intense fact finding for the primary purposes of understanding what happened that day and to honor the crew’s service to our nation.”

The three Airmen who perished are:

  • TSgt. Herman Mackey III, 30, of Bakersfield, Calif.†
  • Capt. Victoria Ann Pinckney, 27, of Colorado Springs, Colo.
  • Capt. Mark Tyler Voss, 27, of Boerne, Texas

A unique combination of six factors – flight control malfunctions, insufficient crew force training, incomplete crew checklist response, use of rudder while in a Dutch roll condition, crew composition, and cumbersome procedural guidance – all came together during the flight’s short 11-minute duration and resulted in this accident.

“The crew encountered a condition that they had not realistically experienced in training, and when coupled with decisions based on their relatively low recent experience levels, were presented with an unrecognized hazardous and difficult situation to overcome,” Arquiette said. “It has been the focus of our investigative team, throughout these months of hard work and travel to the accident scene in the Kyrgyz Republic, to do everything we can to fully understand the facts surrounding this tragic string of events.”

The aircraft was assigned to the 22nd Air Refueling Wing at McConnell Air Force Base, Kan., and was flown by members of the 92nd Air Refueling Wing at Fairchild Air Force Base, Wash. The crew and aircraft were flying out of the 376th Air Expeditionary Wing at the Transit Center Manas.

The report is available on the Air Force Freedom of Information Act Reading Room website, http://www.foia.af.mil/reading/.




All of this week's top headlines to your email every Friday.


 
 

 
Air Force photograph by SrA. Divine Cox

Kunsan AB hosts Exercise Max Thunder 14-2

Air Force photograph by SrA. Divine Cox A South Korean air force F-15 Strike Eagle lands Nov. 17, 2014, during Max Thunder 14-2 at Kunsan Air Base, South Korea. U.S. Air Force, Army, Marine Corps and Navy personnel and aircraft...
 
 

Three bases identified as F-16 aggressor candidate bases

U.S. Air Force photo by Tech. Sgt. Joseph Swafford Jr. A U.S. Air Force F-16 Fighting Falcon fighter aircraft assigned to the 18th Aggressor Squadron lands at Eielson Air Force Base, Alaska, Oct. 6 during RED FLAG-Alaska 15-1. RF-A is a series of Pacific Air Forces commander-directed field training exercises for U.S. and partner nation...
 
 
Air Force photograph

Arc-heated facilities at AEDC offer unique test capabilities for hypersonic programs

Air Force photograph This photo shows the arc heater H3 being test fired prior to the installation of a model injection system. The AEDC High Temperature Materials Characterization and Evaluation is unique in capability and is ...
 

 
Navy photograph

U.S. Navy commemorates C-2 Greyhound’s 50th anniversary of first flight

Navy photograph Nov. 18 marked the 50th anniversary of the first flight of the Navy’s C-2A Greyhound. The “workhorse” of the fleet took to the skies Nov. 18, 1964, from Bethpage, N.Y.   For nearly 50 years, the C-2A ...
 
 

Air Force announces criteria for KC-46A Reserve basing

After extensive internal review, the Air Force on Nov. 9, released the basing criteria that will be used to select candidate bases for the first Reserve-led KC-46A main operating base. The KC-46As will begin arriving at the first Air Force Reserve-led global mobility wing in fiscal year 2019. The basing criteria under consideration include mission...
 
 
Air Force photograph by A1C Erin R. Babis

The footprint of the Jolly Green Giant

Air Force photograph by A1C Erin R. Babis Airmen from the 56th Rescue Squadron tackle Capt. Robert Smith, 56th Rescue Squadron executive officer, after his fini-flight, or final flight, at Royal Air Force Lakenheath, England, N...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>