U.S. Military Grounds All Services’ V-22 Ospreys


The U.S. military announced yesterday (Dec. 6) that all V-22 Osprey tiltrotors are grounded as a result of the preliminary investigation into the U.S. Air Force aircraft that crashed off the coast of Japan last week, killing all eight crew members. Investigators found evidence of material failure in the debris recovered from the water.

In conjunction with Japan grounding its 14 Ospreys last week, the U.S. grounding covers some 400 Ospreys operated by the U.S. Marine Corps, 51 U.S. Navy aircraft and 27 Ospreys operated by the USAF Special Operations Command, the branch that suffered last week’s crash. The U.S. and Japan are the only current operators of V-22s in the world.

Lt. Gen. Tony Bauernfeind, who heads up the USAF Special Operations Command, said he instituted the grounding “to mitigate risk while the investigation continues … Preliminary investigation information indicates a potential material failure caused the mishap, but the underlying cause of the failure is unknown at this time.”

The Air Force declined to estimate how long the standdown would last, but said it expected it to remain in force until the cause of the latest crash is determined and corrective measures implemented.

In the 16 years it has been in service, there have been 12 crashes involving V-22s (two in combat situations), as well as several incidents, with a total of 33 fatalities.

Mark Phelps
Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.


  1. Correct me if wrong.

    According to new publication from Bell Boeing the V-22 fleet since day one has accumulated 600,000 flight hours with 33 fatalities to date.

    Solving for FATALITY RATE:

    Total flight hours: 600,000
    Number of fatalities: 33
    Fatality Rate per 100,000 flight hours = (Number of fatalities / Total flight hours) * 100,000
    Fatality Rate = (33 / 600,000) * 100,000

    Fatality Rate ≈ 5.5/00,000 flit hrs

    NOT 3.69/100,000 flt hrs as published by the USMC

    • MIGHT be the USMC fatalities are less than 33 so it’s a USMC only count? That’s one of the ways they obfuscate statistics.

    • WAIT! Looking at the numbers again, Raf, the TOTAL fatalities in a V-22 are 63 when the flight-testing phase 1991 – 2000 is included. Typically, flight test isn’t that many hours relative to operational hours so if you put 63 into your equation, the fatality rate is 10.5 ! They’re ‘cooking’ the books!

      Grounding this thing was the right thing to do; I’m glad someone woke up. NOW, they need to order them to the boneyard save for a few for spec ops.

    • Even if they have tweaked the numbers, 3.69 is still more than double the average for military aircraft. This aircraft may even be more lethal to the occupants than the original widow maker the F104 Star Fighter. Worse than helicopters, that are pretty much a whole group of parts trying to shake themselves apart. At least you can autorotate a helicopter, I don’t think you can do that in a V-22.

    • Perhaps they are not counting the two lost in combat. If it were shot down, that would be understandable. I don’t know but the military is a dangerous business and I see no need to make comparisions between this machine and civll aircraft as far as fatalities are concerned. Or perhaps these comments just more Boeing bashers looking for a discussion?

  2. how much does this reduce the combat readiness of these service branches? (and I hope they have an equivalent resource to compensate for this–what I hope–temporary situation).

    • A rough estimate according to what I’ve gather, a 25% – 30% decrease in combat readiness. The USMC has about 389 V-22s, where the USAF and Navy have about 50 each. GAO has been critical on the design since its developmental testing.

      Go to: govinfo.gov/content/pkg/GAOREPORTS-GAO-01-369R/html/GAOREPORTS-GAO-01-369R.htm

  3.  Air Force Times

    The mishap is the latest fatal incident involving a U.S.-owned Osprey, in which dozens of service members have been injured or killed in accidents around the world over the past three decades.

    Four fatal Osprey crashes, including Wednesday’s accident, have claimed the lives of at least 13 American troops in the past two years.

    This is the first fatal incident involving an Air Force-owned CV-22 since 2010, and potentially the service’s deadliest accident since 2018, when nine Puerto Rico Air National Guard troops died in a WC-130 weather reconnaissance aircraft.

    The CV-22 Osprey that went down Wednesday is a variant of the V-22 model produced through a partnership between Boeing and Textron’s Bell.

    The tiltrotor aircraft — known for its towering nacelles that allow it to launch and land like a helicopter, and speed forward like a fixed-wing plane — began entering the U.S. inventory in 1999 with the Marine Corps MV-22.

    That program started as a behind-schedule, over-budget invention that claimed dozens of lives during development. In the decades since, Ospreys have proven valuable for their speed and versatility, flying faster than conventional helicopters to approach enemies from unexpected angles or rush wounded troops to emergency care.

    The Air Force received its first combat-ready CV-22 in 2007, and the Navy’s CMV-22 variant took flight in 2020 and deployed with carrier air wings in 2021. None of the sea service’s Ospreys have been involved in fatal mishaps. Japan’s military operates its own Ospreys as well.

    The U.S. military now owns hundreds of Ospreys, largely operated by the Marines. Air Force special operations units use the CV-22 to slip in and out of areas without established runways, where fixed-wing planes may not be able to land with troops and supplies.

    Ospreys can carry nearly three dozen service members or 10,000 pounds of cargo at a time, according to an Air Force fact sheet. Each is armed with a .50-caliber machine gun, and cost $90 million apiece as of 2020.

    The Yokota-based unit involved in the most recent mishap activated squadrons in 2019 to operate and maintain CV-22 Ospreys as part of the Pentagon’s growing footprint in the Pacific.

    But the technological advancements that the V-22 fleets brought to combat and training are still shadowed by concerns about the platform’s longevity and safety.

    “CV-22 readiness keeps me up at night,” then-Col. Dale White, who oversaw acquisition and sustainment for the Air Force’s special operations platforms, said in 2019. “It’s not what it needs to be. It’s a tough platform.

    A combination of pilot error and mechanical failures have contributed to periodic Osprey crashes that, when fatal, have killed multiple troops at once. The military has recently turned its focus to tackling a problem known as a “hard clutch engagement.”

    Last year, Air Force Special Operations Command temporarily grounded its Ospreys following back-to-back safety incidents in which the Osprey’s clutch temporarily slipped and then re-engaged, causing an uneven distribution of power to its massive rotors. Such slips can cause the aircraft to lurch dangerously.

    A hard clutch engagement on both sides of a Marine Corps MV-22 Osprey in June 2022 led to a crash that killed five Marines in California.

    Then in February, the V-22 Joint Program Office — which manages the tri-service fleet — grounded an undisclosed number of Ospreys with more than 800 flight hours to replace aging clutch-related components.

    The office claimed in July it had reduced the likelihood of hard clutch engagements, or HCEs, by 99%.

    “The V-22 community executed 22,258 flight hours between Feb. 3, 2023 and July 19, 2023, with zero HCE events,” the Joint Program Office said at the time.

    The following month, three Marines were killed when their Osprey crashed in northern Australia. The Marine Corps is still investigating what caused the accident.

    “I wouldn’t right now apply a sweeping broad stroke across every incident linking them together,” Pentagon spokeswoman Sabrina Singh said when asked in August whether a clutch malfunction was to blame for those fatalities.

    It’s unclear whether this crash involved a hard clutch engagement.

    According to the Associated Press, Japanese news outlet NHK quoted a local resident as saying he saw the aircraft turned upside down, with fire coming from one of its engines, and then an explosion before it fell to the sea.

    A non-exhaustive history of Osprey accidentsOctober 2023: A Marine was injured after a Marine Corps MV-22B Osprey experienced a hard landing during a training event in Nevada. “Initial assessments indicate the incident was likely not mechanical in nature,” a Marine Corps spokesman said in October.September 2023: Three Marine Corps Ospreys diverted from scheduled flight paths in a single week due to “caution indications” in the cockpit. The service said the warnings did not appear to be prompted by clutch issues.August 2023: Three Marines were killed in an MV-22 Osprey crash in Australia during a multinational training exercise.October 2022: The engine of an Marine Corps Osprey caught fire during training at Air Station Miramar, California. No one was injured.
    Summer 2022: Air Force Special Operations Command’s CV-22 Osprey aircraft face two hard clutch engagement problems.June 2022: A problem with the clutch of an MV-22 Osprey aircraft caused the June 2022 crash that killed five Marines, according to a Marine Corps investigation released this July.March 2022: Marine Corps aviation investigators have determined that a fatal March 18 MV-22B Osprey crash near Bodo, Norway, that killed four Marines was pilot error.September 2017: Two service members were injured when a Marine MV-22B made a hard landing in Syria.August 2017: Three Marines were killed when their MV-22B Osprey crashed off Queensland, Australia.May 2015: Marine Corps officials determined that decisions made by pilots in low-visibility conditions contributed to an MV-22B Osprey crash in Hawaii that left two dead and 20 more injured.October 2014: One Marine died when he jumped from an MV-22B Osprey that nearly crashed shortly after taking off from the flight deck of an amphibious assault ship. The Defense Department reclassified his death as one that occurred in support of the military’s effort to combat the Islamic State group, making him the first official casualty of Operation Inherent Resolve.June 2012: Five airmen were injured when a CV-22 was destabilized by the wake of another Osprey near Hurlburt Field, Florida.April 2012: Two Marines died and two were severely injured when an MV-22 Osprey crashed in a Moroccan military training area while participating in a bilateral exercise.April 2010: A CV-22 Osprey accident near Qalat, Afghanistan, killed four people and injured 16 of the 20 onboard.April 2000: An MV-22 Osprey crash at Marana Regional Airport in Arizona killed 19 Marines.

    Marine Corps Times reporter Irene Loewenson contributed to this write up.

    Rachel Cohen is the editor of Air Force Times.

    • I have research that can explain why at least 5 of the Ospreys have crashed. Like helicopters, Ospreys are very vulnerable to certain atmospheric conditions. I have found these atmospheric conditions to have been present when these Ospreys crashed. My research shows this atmospheric condition was present and is what caused the Osprey to crash on November 29, 2023. Is anyone interested?
      Ronald B. Hardwig, Professional Engineer

  4. These numbers will certainly change one way or the other when the US Navy replaces the C-2 Greyhound in the carrier resupply mission (COD). If I am not mistaken, I think the Navy has already transitioned at least one C-2 unit over to the V-22.

    The COD mission will certainly test the V-22’s reliability and capabilities. The COD mission is demanding, delivering cargo, replacement crew, mail, and visitors to carriers at sea under all conditions. Unless the DOD gets a handle on the V-22’s issues, this may be a short-lived mission. With the Navy only having 50 V-22s to service all the carriers at sea, I can foresee some problems keeping the carriers supplied if there are continuing maintenance or safety issues with their V-22s.

  5.  As of November 2023, 16 V-22 Ospreys have been damaged beyond repair in accidents that have killed a total of 62 people.

    Four crashes killed a total of 30 people during testing from 1991 to 2000.

    Since the V-22 became operational in 2007, 12 crashes, including two in combat zones,and several other accidents and incidents have killed a total of 33 people.

    95 people have been killed in total in Ospreys since testing began in 1991.

  6. As of July 20, 2022, the USMC, before two further fatal Osprey crashes which might be again attributed to possibly ” clutch slip disengagement “, still stood firm in their endorsements of the Osprey :

    Several media outlets have noted the history of the Osprey and fatal crashes and nonfatal mishaps. Since initial flights in 1989 with prototype aircraft, at least 51 military members have died in connection with mishaps or crashes involving the Osprey.

    USMC Major Jorge Hernandez provided larger context regarding data on Marine aviation, noting that only in the past decade the aircraft has flown more than 420,000 flight hours, more than half of that in the past five years.

    “The 10-year average mishap rate for MV-22′s is 3.16 per 100,000 flight hours,” Hernandez wrote on July 8.

    For comparison, that rate is lower than the AV-8 Harrier jet, variants of the F/A-18 Super Hornet, the F-35B fighter jet and the CH-53E Super Stallion. The 3.16 Osprey mishap rate is near the total Marine aviation platform average of 3.1 per 100,000 flight hours, the major wrote.

    The Osprey aircraft, Hernandez wrote, flies nearly double the hours of the Corps’ other rotary wing platforms. The major called the aircraft the “workhorse” of the service’s assault support community, with capabilities far exceeding the CH-46, which it has supplanted for most missions.

  7. Go to: govinfo.gov/content/pkg/GAOREPORTS-GAO-01-369R/html/GAOREPORTS-GAO-01-369R.htm

    Takeaways from the 2001 GAO (page 31) Executive Summary on VRS:

    1. Vortex Ring State (VRS) is a serious threat to rotary-wing aircraft, including the V-22.

    VRS occurs at low airspeed and high sink rate, causing sudden and potentially uncontrollable rolling and diving. In the V-22, VRS can affect only one side of the aircraft, leading to a rapid roll and steep dive. At low altitudes, recovery from VRS may be impossible.

    2. VRS was known to exist in the V-22 but its severity was underestimated.

    Testing prior to operational evaluation (OPEVAL) did not fully anticipate the extreme and unexpected attitude changes caused by VRS.

    3. VRS warning signs may be inadequate or absent.

    Pilots may not receive clear warnings before entering the danger zone for VRS.
    Certain pilot inputs, like roll or yaw commands, can trigger VRS more easily.
    This problem is amplified during high workload situations like night flying, system malfunctions, or hostile environments.

    4. Further testing is needed to better understand and mitigate VRS in the V-22.

    High rate-of-descent (HROD) testing is ongoing to further define the VRS phenomenon.
    Improved pilot training and awareness are crucial to prevent VRS incidents.

    Overall, the executive summary highlights the serious nature of VRS in the V-22 and calls for further research and mitigation efforts to ensure pilot, crew and grunts safety and prevent future accidents. Then there’s the problem of debrie and sand into the cockpit and instruments during hover, takeoffs and landings under training or combat situations.

    Larry, you are correct!

    • Ultimately, the V-22’s legacy will be determined by its long-term performance and its ability to fulfill its intended mission objectives while ensuring the safety of its pilots, crew, grunts, and then everyone and everything within 500 feet of the contraption.

    • During testing of the XV-15, I wish you coulda seen the gyrations that thing was doing during early testing. VRS was likely one of the issues that no one knew about. Your 500 foot “contraption exclusion radius” might not have been enough? 🙂

      BTW: I’m not a Boeing ‘basher.’ I see myself as a realist with LOTS of flight test experience. People don’t realize that there’s a long logistical process involved with taking a military ‘need’ from an idea to funding to RFP to flight test and — ultimately — real hardware in actual operational use by warfighters. In the case of the tiltrotor, there were many good mission reasons to have such a machine. Realistically, however, there were also MANY warnings that the design was fraught with shortcomings. No one paid attention … they were all focused on having a machine that woulda worked in the Iranian hostage situation. NOW, however, after real world operational experience has shown its shortcomings, it’s time for reevaluation and correction or retirement. Don’s comment (below) summarizes the basis for MY position on the thing.

    • I don’t understand something. The V22 uses two rotors separated by a wingspan. The CH47 Chinook uses two rotors separated by a fuselage. The only other difference is the V22 rotates the nacelles. So why does the V22 seem to have a more complicated mechanical arrangement with clutches and stuff? Yet the V22 has several fatal flaws: clutch engagement problems, large root-to-tip twist to the blades, engines rotate through 90 degrees during operation. Sounds like a new V22 needs to be designed with a simpler powered lift system.

  8. Military aviation has always been dangerous. While on active duty in the US Navy we rejoiced when we were able to reduce the mishap rate below 4.0 The vast majority of these mishaps were pilot error. Now days we have applied lessons learned and pilots are flying smarter so its particularly disheartening to see so may Fatal Mishaps through no fault of the pilots.

  9. Just looking at it logically, the aircraft is very complicated structurally, and is going to be prone to mechanical accidents. Helicopters are a known, proven airframe. The Military/Congress screwed up and ordered an unsafe device.

  10. Yes, many military aircraft are dangerous but at the same time are equipped with ejection systems when things go south. The V-22 has no such system while at the same time going south more often than other aircraft.

  11. All we can hope is that — finally — someone at the ‘top’ of the DoD is paying attention and has enough horsepower to either fix or put an end to this thing. From where I sit, I think the design ITSELF is part of the problem. For a time, I worked in reliability engineering on a major aerospace system after my USAF time. I learned a lot about that design viewpoint. SOME of the failure modes of the V-22 may not be able to be resolved. Better maintenance and more pilot training can’t repair a fallacious design. And THAT is where I think the bottom line is.

  12. All these Tilt Rotor Aircraft, going back to the 1950’s – with types such as the XV-3, X-18, etc. were all fraught with design deficiencies that were not entirely surmountable. The projects were all canceled.
    Looking at the accident rate figures and fatality numbers I posted above (for instance, 30 + people killed alone in the Testing Phase from ’89 to 2000) this project should have died on the drawing board. Yet the MIL, especially the USMC put all its eggs into one basket with the MV-22 because to them, Ospreys can carry nearly three dozen Combat service members or 10,000 pounds of cargo at a time. Minimum pax load for the USMC is 24 Combat Ready Marines + payload cargo. The Osprey aircraft, USMC Maj Jorge Hernandez writes, “flies nearly double the hours of the Corps’ other rotary wing platforms. The Major called the aircraft the “workhorse” of the service’s assault support community, with capabilities far exceeding the CH-46, which it has supplanted for most missions. The MV-22 /CV-22 can slip in and out of areas without established runways, where fixed-wing planes may not be able to land with troops and supplies.”
    And as GJ pointed out above; the COD missions are underway using the Osprey by the USN, now too.
    The US MIL is not going to give up “easily” on their ” all eggs in one Basket: CV/MV -22/B.

    2006 — https://www.hurlburt.af.mil/News/Features/Display/Article/206677/tilt-wing-aircraft-traces-beginnings-to-1954/

  13. Reprising a reply I posted on December 5:

    As an 82 year-old who has been a GA pilot for almost 57 years, I have had more than just a casual interest in aviation developments and innovations. I have no engineering background, so I just kind of rely on observation and instinct as I evaluate various projects that propose to advance the practicality and versatility of aircraft designs. A criterion that I sometimes use to evaluate a new design goes something like this: If I had the opportunity to invest in this particular design, would I feel confident in doing so?

    I have seen so many failures, so many dead-ends, so many flash-in-the-pan ideas and designs over the years (Flying cars, anyone? Really? Jim Bede maybe? Oh my!) that those kinds of investments do not seem to be a good idea.

    From the git-go, I never thought that the Osprey was a good idea. I never would have invested in it (not that I could have, of course). I still think that it’s not a good idea. Let it lie with the Colonial Skimmer, the BD-5, the Aerocar, the Convair XFY-1 Pogo, the Windeker Eagle, Terrafugia and the hundreds of other projects that often have advanced the cause of aviation innovation but have not survived the intense scrutiny of enduring practicality.

    Like so many designs that have preceded it, it was a nice try. Now it deserves to be mercifully put down.

  14. Bob ABQ

    Not trying to diminish the death of any of our dedicated services members. But using the number of fatalities per total hours flown gets you to occupant safety. Aircraft inflight incidents per total hours flown would get you closer to the stat you’re looking for…Aircraft reliability. And further refined to include pilot error/or not, etc.

    Whether loaded with solders or loaded with rations these aircraft would have crashed either way and for the same reasons. But the stats would have been very different. Think 747 with full passenger load verses single seat fighter jet. Vastly different occupant safety stats…But only one aircraft incident stat.