Is the V-22 Osprey an Unsafe Aircraft? Why Can't the US Army Give Up V-22s?

About a week ago, a US Air Force CV-22 Osprey aircraft crashed off the southern coast of Japan on November 29, 2023. Seven airmen were on board. The Air Force recovered the sunken Osprey and the remains of 5 airmen. It remains unclear what caused the accident. At least, no explanation has been given as to whether the accident was caused by the clutch mechanism. On the other hand, Japanese news organization NHK reported that an eyewitness said that the plane flipped over, there was a fire in one of its engines and then heard an explosion before falling into the sea.

The downed aircraft belonged to the US 353rd Special Operations Unit based at Yokota Air Base near Tokyo. This latest fatal accident has once again raised questions about the Osprey aircraft. In the last two years alone, there have been four fatal Osprey accidents and a total of 13 American soldiers have lost their lives in these accidents.

Hybrid Air Vehicle V-22 Osprey

The V-22 Osprey is a joint production of Boeing and Textron Bell. The letter V stands for Vertical Take-off. The V-22 is a tiltrotor aircraft that can take off and land like a helicopter and fly like a fixed-wing airplane. Theoretically, the tiltrotor transforms the rotors into propellers by transferring lift from the rotors to the blades, overcoming the limitation of conventional helicopters' inability to reach high speeds due to the structural limitations caused by their blades with the Osprey-designed helicopter-aircraft hybrid structure. The V22s are thus able to reach significantly higher speeds. The first aircraft of its kind is a pioneering aircraft. For the first time in the world, a tiltrotor system was used on this air platform. However, the Osprey is a very expensive aircraft compared to a conventional helicopter, and its design has been known to cause a number of major malfunctions.

Despite this, versions of the V-22 Osprey hybrid aircraft continue to be used predominantly by the US military. In 1999, the Marine Corps used MV-22s, in 2007 the Air Force used CV-22s, and the Navy has been using CMV-22s since 2021. Apart from the American army, the Japanese army also uses these aircraft. The airframes of all these V-22 models are almost 90% similar to each other. The main difference between them is the avionics they use. The Air Force version, the CV-22, can carry 18 troops and has an operational radius of about 500 miles.

Ospreys are more versatile than helicopters. Its high speed allows for versatile use. V-22s are used to penetrate enemy territory from different directions at very low altitudes at high speed, to conduct airborne-airborne troop mix operations, or to carry out amphibious assaults in naval operations in a much shorter time than conventional helicopters.

The US military currently has hundreds of Ospreys, largely operated by the Marine Corps. In recent years, the Air Force has deployed CV-22 Ospreys to Japan as part of a growing American footprint in the Pacific. It has expanded the CV-22 operations center at Yokota Air Base. Air Force special operations units use the CV-22 to fly in and out of runway-less areas where fixed-wing aircraft cannot land with troops and supplies, and to some extent to conduct flying troop operations. CV-22s can carry up to 10,000 pounds of cargo when transporting only supplies, and can accommodate up to 36 troops in troop transports. A .50 caliber machine gun is mounted on CV-22s for use in special operations missions. The estimated sales price for CV-22s is around USD 90 million. We are talking about an airplane-helicopter hybrid aircraft for almost the price of an F-35. In order to fly CV-22s, one has to bear a considerably higher price tag compared to normal general purpose helicopter prices. 

The additional technological capabilities that V-22 fleets bring to the battlefield based on their hybrid feature may not make much sense when human life comes into play. Growing concerns that Ospreys have flight safety issues jeopardize the future of the aircraft. It is also a very difficult aircraft to maintain, necessitating low activity rates. In 2011, the US Air Force deployed a large number of V-22s to Sigonella Air Base in Sicily, where I served as the Commander of the Turkish Deployment Unit during NATO's Libya Operation. There, I closely observed how complicated this aircraft was, a set of systems that required a lot of effort from the maintainers.

The US Air Force had decided not to fly the aircraft until a solution was found with a new design for the clutch system, which frequently fails in the equal and balanced power distribution between the huge rotors that caused the recent Osprey accidents. This was because the resulting different operating frequency between the two rotors could cause emergency situations, including yawing and loss of control. For example, the MV-22 Osprey of the Marine Corps crashed for this reason during a flight in California in June 2022. This accident prompted the Pentagon to take urgent measures and flights were put on hold until this problem was fixed. Improvements, together with evidence that the problem had been fixed, allowed the V-22s to resume flights. During the 22,258 flight hours between February 3 and July 19, 2023, as part of this improvement process, there were zero clutch system failures. This helped alleviate flight safety concerns about the Ospreys. However, three American soldiers were killed when the MV-22 crashed in northern Australia in August. Although the exact cause of the crash is not yet known, this accident triggered concerns again.

Some Known Problem Areas of Ospreys

Low Flight Availability Rate 

The Osprey is more than twice as expensive as a helicopter with the same lift capacity, and at least twice as expensive to maintain. Due to its heavy maintenance requirements, its activity rate is considerably lower than that of a helicopter. The return-to-flight rate is a much smaller percentage than that of a normal helicopter. To give you an idea, it is known that the availability of the V-22 in the US Marine Corps hovers around 60%, the lowest operational rate after the CH-53Es, which are currently waiting to be replaced by CH-53Ks. On the other hand, if it is remembered that the V-22's average activity rate between 2009 and 2011 was 53%, it will be seen that there is still a positive increase in Osprey activity percentages.

Altitude Restriction (No Aircraft Pressurization)

The cabin of the aircraft is not pressurized. This means that, contrary to claims, this plaftorm cannot use high altitudes to move troops from one place to another. It also means that the high altitude cruise capability touted for the Osprey can only be sensibly used for cargo. Because when the aircraft cruises above 10,000 feet and goes to a drop zone, the use of high altitude would not be practically meaningful, as the soldiers would be landed on the ground in an almost ruined and distraught state, unable to fight. 

Perhaps it could be mentioned that there is an oxygen system, but while there is no limitation on oxygen masks for the flight crew in Ospreys, there are not enough oxygen masks for the soldiers carried in the cabin due to system limitations in the aircraft (not enough mask connections). If the aircraft has to go to altitudes where oxygen masks have to be used, this platform, which can normally carry 24 soldiers, will instead be limited to carrying only 10 soldiers. This means a 60% capacity reduction.

Pentagon's Restriction on the Number of Troops to be Carried on Osprey

By the book, Ospreys are supposed to carry 24 fully equipped soldiers. However, when there are 24 fully equipped soldiers on board, the cabin becomes very cramped. Evaluating this, the Pentagon, calculating that the transfer of cramped troops to the battlefield would bring about fatigue problems as well as morale motivation, issued instructions to limit these platforms to carrying 18 fully equipped soldiers instead of 24. This limitation can only be suspended in emergency evacuation conditions.

Osprey Operations Damaging Ship Decks

The rotors have a smaller disk area than rotors on an airplane or helicopter of similar weight. For this reason, the Osprey cannot make a landing as calm and stable as a helicopter. Technically, a 'beautiful' landing is out of the question. A more rapid landing is required. This means that the Osprey cannot land close to human populations like helicopters for flight safety reasons. 

It also has to cope with hot engine exhaust downwards due to the position of the engines on landing. In particular, the lifespan of the military ship decks on which the Osprey lands is shortened, as it has to project a much higher pressure of hot gas onto ship decks than a normal helicopter. Deck maintenance is completed in a shorter period of time compared to normal ships, and this has to be 'billed' to the Ospreys as a factor that increases the maintenance costs of the ship. After all, these planes cannot land everywhere that a helicopter can, and ship commanders do not want Ospreys to damage their ships unless they have to.

Personnel having to be suspended from a height with a descent rope on ship decks

The altitude at which Osprey can safely hover is around 150 feet. At this altitude, a hover is performed over the target ship and the personnel to be lowered on board are suspended to the deck with landing ropes. On the other hand, this altitude is a very high and risk-increasing hover altitude. While a US Navy MH-60 helicopter can easily perform this task at a hover altitude of 15 feet, even over very small ships, the Osprey needs an altitude of 150 feet to perform the same task. In fact, it is not desirable for the personnel using the landing ropes to land below 150 feet on the deck of the ship with more anxiety if there is a bit of wind at that moment. This type of landing became famous among American sailors as the "elevator of death". Moreover, due to the 150 feet criterion, it is not possible for Ospreys to land personnel on small ships. 

Ospreys Need More Space on Ship Decks

Due to the design of Ospreys, pilots cannot see the landing area as clearly as a pilot in a helicopter cockpit. The pilot needs the support of radar and advanced avionics systems in order to be able to descend at the same height as on the landing approach. In normal helicopters, however, such systems are almost never needed during landing. This difference in landings causes the Ospreys to require a larger clear deck area in case of pilot error during landing. This requirement is not preferred in amphibious assault ships where Osprey landings will be made due to the safety constraints it imposes on deck space.

Overheating Problems in Osprey Gearboxes

The Osprey cannot stay in the air as long as a helicopter. After a short flight in helicopter mode, it is necessary to switch to airplane mode. Otherwise, the gearboxes are subject to overheating. This is seen as an obstacle to the effective use of Ospreys in short-distance search and rescue missions. However, most helicopters can fly unrestricted for as long as their fuel is sufficient and complete their missions without overheating any of their components. 

Lack of Armor to Protect Soldiers Carried in the Osprey Cabin

In order to carry the heavy loads expected of it, Osprey has reduced its own fuselage weight. For this purpose, most of the fuselage was made of very light composite material. In addition, some parts of the aircraft, such as the engines and gearboxes, were armored so that the Osprey could survive under fire. Unlike most helicopters, there is no armor protection in the main cabin where the troops are carried. Although there were voices raised a few years ago about armoring the Osprey cabins with armor, the fact that the aircraft was already a heavy aircraft caused this armor request to be quietly forgotten since it was above the target weight.

Ospreys' Susceptibility to Vortex Ring State (VRS) Problems

The Osprey also has many aerodynamic problems. Vortex Ring State, or VRS for short, a type of rotor stall that all helicopters can experience when descending for landing or hovering in turbulent conditions, is a much more significant problem for the Osprey than for normal helicopters. When in hover mode, V-22s are prone to VRS problems. The V-22 is more likely to experience VRS. It is also much less likely to recover from this emercency than a helicopter. If a severe VRS occurs in the Osprey below about 1,600-2,000 feet relative to the ground, it is likely that the aircraft will somersault and have to dive inverted to the ground. Although operational constraints have been put in place to prevent this, the VRS problem is inherent in the V-22 design and the probability of encountering it is quite high if the constraints are not adhered to. 

Why Can't the US Army Give Up the Osprey?

Despite the fact that the Osprey is such a "problematic aircraft", the US and partly Japan continue to use this hybrid aircraft for operational reasons. Let us briefly mention these.

The Osprey is considerably faster than helicopters used for similar purposes. It also has a much longer range thanks to its high-altitude cruise capability. When the aircraft is cruising, it effectively transforms into a turboprop aircraft like a normal airplane. It is therefore more fuel efficient than a helicopter. This allows the aircraft to have a much larger operating radius. In addition, it is also possible to move material from one place to another much more quickly and more efficiently than helicopters.

On the battlefield, the rapid movement of troops and supplies often provides significant added value. The Osprey's high speed is always praised by the soldiers who use this platform in the theater of operations. Although the cabin comfort is a bit poor, the fact that the Osprey does a much better job than helicopters in carrying combat-ready troops is a factor that makes you forget about the cabin comfort, since you don't stay in the cabin for that long.

While the V-22 is an extremely expensive and difficult to maintain aerial platform with a relatively low operational rate, it is the only aircraft in the world that can help the US maintain its amphibious capabilities in the face of emerging threats. Yet the United States still sees itself as a naval power, and following Mahan's lead, Washington sees having a naval power as a sine qua non for continued American hegemony. This is because the US superpower status is fundamentally based on the strength of its navy. However, in order for the US military to go to war on the Eurasian continent, it is desirable for the US Marine Corps to have highly developed amphibious landing capabilities. 

Enables Force Projection to the Landing Zone from Outside the Anti-Ship Missile Range

On the other hand, the proliferation of anti-ship missiles deployed in landing zones is making it increasingly difficult for the US Marine Corps to conduct amphibious landings. To conduct amphibious operations, the US needs systems with longer ranges than modern anti-ship missiles. Most helicopters have a combat radius of around 100 miles. Variants of relatively old anti-ship missiles like the Harpoon have ranges of around 150 miles. Modern supersonic anti-ship missiles such as the P-800 have ranges of around 180 miles, at the limit of the missile technology control regime. As a result, an amphibious landing force that relies on conventional helicopters to land forces on the ground is vulnerable to advanced air defense systems. The same is true for ships. Incidentally, a modern amphibious assault ship costs $10 billion, while P-800-like anti-ship missiles cost around $1 million. All in all, in the amphibious landing dimension, the economics of war definitely work in favor of the defense.

At this point, we are faced with the fact that the V-22 is a unique aircraft. This is where the importance of the aircraft comes in. Because it can take off vertically, it can land on amphibious assault ships and other naval vessels. It has a very large operating radius, a radius of 390 miles. It can thus support a landing operation from 150 miles away, leaving ships behind, well beyond the range of all anti-ship missiles under the Missile Technology Control Regime. It should therefore remain an indispensable platform, one of the few US combat systems capable of landing Marines beyond the range of anti-ship missiles. Although there have been problems with this program as with any new technology, the US still needs the V-22 to continue projecting power from the maritime domain.

Conclusion

The US-made Osprey is a hybrid aircraft that takes off and lands like a helicopter, but can travel much faster like an airplane by rotating its propellers forward during flight. Air Force special operations units use the CV-22 to fly in and out of runway-less areas where fixed-wing aircraft cannot land troops and supplies. In amphibious operations, the Marine Corps relies heavily on the Osprey for power projection to the landing zone, especially in anti-ship threat environments. Ospreys, which offer many more operational capabilities than helicopters, have some known design problems and can cause the death of many soldiers in the event of an accident, so efforts are underway to develop new versions and find solutions to design problems. 

ABD Uçuş Emniyeti Vakfı tarafından tutulan bir veri tabanına göre, 1992'den bu yana Osprey kazalarında 50'den fazla kişi hayatını kaybetti. Bu nedenle oldukça yüksek riskli bir uçaktır. In addition, the Osprey is an expensive aircraft. Its activity rate is low. As seen in the November 29 accident off the coast of Japan, it has a risky operational history. Nevertheless, the operational benefits offered by this platform are recognized by the US Army, which is why it remains indispensable. 

References

Jonathan Lehrfeld, Rachel S. Cohen. “What is the Osprey, the aircraft at the center of multiple tragedies?” ArmyTimes, 1 Aralık 2023, https://www.armytimes.com/news/your-air-force/2023/11/30/what-is-the-osprey-the-aircraft-at-the-center-of-multiple-tragedies/

Mari Yamaguchi, The Associated Press and Rachel S. Cohen. “Divers find sunken Osprey, remains of 5 airmen, Air Force says”, AirforceTimes, 4 Aralık 2023, https://www.airforcetimes.com/news/your-air-force/2023/12/04/divers-find-sunken-osprey-remains-of-5-airmen-air-force-says/?utm_source=sailthru&utm_medium=email&utm_campaign=air-dnr