The V-22 Osprey’s deadliest accident stemmed partly from “undeniably intense” pressure to show progress for the new tilt-rotor aircraft, according to the U.S. Marine Corps commandant.
“As I reflect on the mishap I cannot ignore the charged atmosphere into which the pilots flew that night, carrying on their shoulders a critically important program,” General James Amos wrote two lawmakers in a look back at the crash in 2000 that killed 19 Marines. “I believe they were eager to vindicate a revolutionary technology.”
While the accident happened more than 13 years ago, the lessons cited in the December letter, obtained by Bloomberg News under the Freedom of Information Act, may apply to similar pressures the military is under today to prove the value of new weapons such as Lockheed Martin Corp.’s F-35 fighter and the Navy’s Littoral Combat Ship in a time of defense budget cuts.
“I remember well the aches and pains of the V-22 program,” Amos said at a Rand Corp. conference in January, when asked to compare the V-22 with the Marine version of the F-35 that the service is trying to declare ready for combat as soon as July 2015. “We are not going to repeat those” issues, said Amos, who was assistant deputy commandant for aviation and involved in overseeing the V-22 in 2000.
The Osprey can take off and land like a helicopter, and its propellers tilt forward so it can fly like an airplane. After early years of setbacks and accidents, the aircraft built by Boeing Co. and Textron Inc.’s Bell Helicopter unit served in Iraq and Afghanistan. Congress has appropriated $41.5 billion toward a $55 billion program to build 460 of the V-22s.
The letter from Amos was addressed to Representatives Walter Jones, a North Carolina Republican, and Steny Hoyer, a Maryland Democrat. They’ve championed the cause of the widows of the two pilots who died in the 2000 crash. The women, who live in the lawmakers’ districts, have long fought the notion that their husbands were at fault.
“Among the greatest misfortunes” after the crash “was the characterization -- not by the Marine Corps but by others -- that pilot error was solely to blame for the mishap,” Amos said in his letter, although he stopped short of saying it played no role.
One of the widows, Connie Gruber, who lives in North Carolina, said in an e-mail that she’d seen the letter from Amos and didn’t want to comment.
“But I trust you will be respectful of my husband and his comrades,” she said. The other widow, Trish Brow, who lives in Maryland, had no immediate comment.
Sarah Howard, a spokesman for Jones, said he had no comment. Hoyer spokeswoman Katie Grant said in an e-mail that she didn’t have the letter.
The April 8, 2000, night flight test that turned deadly was part of a series of combat evaluations needed before a decision planned for that December to move to full production of the V-22, with an estimated value of as much as $20 billion to the contractors.
“The pressure to succeed that night hung heavily in the air, touching everyone associated with the program,” Amos wrote.
Instead, the decision was delayed almost five years after the April crash was followed within months by a negative report on the V-22’s reliability by the Pentagon’s top weapons tester, and then by another crash, this one attributed to flawed hydraulics, that killed four Marines.
While the Marine Corps has never directly blamed the pilots for the April 2000 crash, it cited “human factors.” Jones has pressed the service for years to say the pilots weren’t at fault.
The Marine Corps’ explanation in 2000 “failed to adequately account for the many intangibles contributing to the outcome,” Amos said.
The pilots, Lieutenant Colonel John Brow, 39, and his co-pilot, Major Brooks Gruber, 34, were among the most experienced V-22 pilots in the Marines, the head of Marine aviation said after the accident. Brow had flown about 97 hours and an additional 94 hours in a Osprey simulator. Gruber had flown about 86 hours, and 121 more in a simulator.
“They were superb aviators, among the finest in our Corps,” Amos said. “Notwithstanding their talent and skill,” the Osprey, “like all new aircraft, contained certain unexplored capabilities and limitations at the time of the mishap.”
The crash during a night exercise in Marana, Arizona, was pegged to an aerodynamic condition that the pilots weren’t fully informed about, according to several reviews by the Marine Corps and other agencies.
Vortex Ring State
The program “did not significantly recognize the potential safety threat” that a condition called a Vortex Ring State poses to a tilt-rotor aircraft, Amos said, and “as the pilots attempted to stay in position” during landing “the aircraft subsequently entered VRS and crashed.”
The condition occurs when an Osprey’s or a helicopter’s rotor blades lose lift as it’s descending. Rather than correcting the condition, adding power makes it worse.
In the 2000 crash, the V-22 descended more than 1,000 feet per minute instead of the permitted maximum of 800 feet per minute, according to investigators.
“The test program did not fully define it and the engineering and safety program failed to forecast the characteristic” and “clearly communicate” to fliers “the potential safety issue,” Amos said.
Lieutenant Colonel David Nevers, a spokesman for Amos, said in an e-mailed statement that the commandant’s letter came after “considerable reflection over many months and careful re-examination of the many factors that led to the tragedy.”
“General Amos drew on his experience as a pilot, his long history with the V-22 program, and the advantage of time to offer his own perspective,” Nevers said.