Davis-Monthan Air Force Base Is The Final Resting Place Of Old Military Jets. Why?

Out in the high desert of Arizona, thousands of U.S. military aircraft sit in neat, tidy rows baking under the sun. These are aircraft that served their country with honor and dignity, but they have run their course and are done flying. 

At least for the time being. See, there are several stages of storage in the Boneyard. Some are permanent, while other stages are aircraft kept in a more readily accessible state. And, in fact, some aircraft are pressed back into service. Others are stripped of everything useful and cannibalized for parts. 

We’re going to walk through the boneyard virtually today, and see what all it is, how it is run, and what exactly the government does with all of those aircraft. 

What is an Aircraft Boneyard?

As cool as the name is, the Boneyard is not the official name for the resting place for military aircraft. Also, while the majority of the aircraft stored are Air Force, there are aircraft from all five branches of the U.S. Department of Defense. 

After World War II, the Army's San Antonio Air Technical Service Command set up a storage facility for B-29 and C-47 aircraft at what was then Davis-Monthan Field. In April 1946, as Davis-Monthan became part of the Strategic Air Command, the 4105th Army Air Force Base Unit became an independent tenant facility. 

By Aspersions, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2194003

Today, this facility, now known as the 309th Aerospace Maintenance and Regeneration Group (AMARG), is responsible for the storage of nearly 3,200 aircraft and over 6,300 engines from the five branches of the Department of Defense, as well as various U.S. government agencies, including the Department of Homeland Security (Coast Guard, Customs and Border Protection), NASA, the Department of Agriculture (U.S. Forest Service), the National Science Foundation, and the Smithsonian Institution. Additionally, AMARG stores aircraft for allied nations and maintains nearly 280,000 line-items of aircraft production special tooling and special test equipment.

The Tucson area was chosen for this storage center primarily due to its low humidity and alkaline soil, which allow for indefinite aircraft storage with minimal deterioration and corrosion. The soil, known as caliche, is extremely hard, enabling even the heaviest aircraft to be parked directly on the desert floor without the need for concrete or steel parking ramps.

This facility is a vital force multiplier for the Department of Defense, enabling the United States to rapidly adapt to global changes, national security threats, and fiscal realities. As America’s National Airpower Reservoir, AMARG has played a significant role in major post-WWII events, including the Berlin Airlift, the Korean War, the Cuban Missile Crisis, the Vietnam War, Operation Desert Storm, Bosnia/Kosovo, Operations Iraqi and Enduring Freedom, and the global war on terror. 

The Lifecycle of Government Aircraft

There are a few important things to know about how the government retires aircraft from service. 

First and foremost, there are two sorts of retirements: one involves a reduction in the total number of aircraft, while the other is the total retirement of an airframe. 

The former is a lot more common, and is often done due to fiscal constraints. Instead of retiring an entire fleet of jets, it is much cheaper to retire a portion of the fleet which also returns serviceable parts back into the supply chain. 

Most of the fleets have been reduced over time to make room both in the fleet and budgetary cap for new aircraft. 

However, certain aircraft have been completely retired from active service and replaced. The E-11A Battlefield Airborne Communications Node (BACN) was commissioned and is doing the role of several aircraft, one of which it completely replaced was the E-8 JSTARS which has been retired from service. 

The concept of a lifecycle is established during the design and commissioning phase of all aircraft that enter military service. However, this is a speculation based on the needs of the military and their projected service life. But, this is highly speculative at best. Jets like the KC-135 and B-52 are easy targets that continue to serve well beyond their expected life cycles, but other aircraft like the T-38 are very old. The A-10, which has never had a true replacement, soldiers on in spite of almost constant pressure to retire. 

The C-130 Hercules is just as old as the KC-135 and B-52, although a lot of people forget this. Also, the J models are all low time airframes, significantly reducing the burden on the aging fleet. So, lifecycles are incredibly hard (if not impossible) to predict at the outset of a design or acquisition. Reliable supply chains are imperative to keeping these fleets reliable. 

Storage and Preservation

The 309th AMARG is the military unit tasked with preserving the jets of the boneyard and putting them to bed. There are several broad steps in the process. 

Initial Inspection & Preparation

When aircraft arrive at AMARG, they are thoroughly cleaned to remove dirt, grime, debris, and especially anything that could cause corrosion. Corrosion is public enemy #1 to aircraft, which is essentially why they are parked in Tucson in the first place. 

All fuel, hydraulic fluid, oil, and other operational fluids are drained from the aircraft to prevent leaks and minimize the risk of corrosion.

Corrosion Prevention

The next phase in the process is to actively prevent corrosion.

  • Sealant Application: Key areas of the aircraft which include engines, windows, and other openings, are sealed with special coatings and sealants to prevent moisture ingress and protect against corrosion.
  • Desiccants and Moisture Control: Desiccants, which are materials that absorb moisture, are placed in the interior and other sensitive areas of the aircraft to keep humidity levels low. This is critical in preventing corrosion and maintaining the integrity of electronic systems.

Protective Wrapping

Now that they are clean, they are sprayed with a coating called Spray-Lat. Spray-Lat is a UV blocker to preserve the metal of the aircraft in the long term. It also helps maintain consistent internal temps, which is important since the desert tends to get hot. 

The coating is then regularly inspected and reapplied when necessary to make sure that aircraft remain protected. 

Storage & Maintenance

Again, these aircraft are kept out in the open desert for good reasons. Tucson is extremely dry, averaging less than a foot of rain per year. It is sunny most of the year, making it the ideal place for aircraft to sit for years on end and still be usable. 

With that said, periodic maintenance must be undergone to ensure these aircraft can be pulled out of storage. This usually includes checking all rubber and silicone seals and hoses on the aircraft, rotating tires, and so on. 

By aeroprints.com, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32532729

Parts Reclamation and Reuse

Finally, there are basically three end uses for government aircraft that have been parked. 

First, they are kept in a recall condition to be pulled back to the fleet. It does take a number of months to do, but it does happen. 

Second case, the aircraft that are not intended to fly again may have their parts harvested for reuse in active service aircraft. These parts are carefully removed, inspected, and reconditioned as needed.

Finally, there is the case where an aircraft is no longer useful either as a whole or for parts. If all the parts have been successfully removed, the aircraft can be dismantled and scrapped. 

Aircraft Resale and Transfer

Aircraft that have been mothballed in the boneyard are not disqualified from being sold to foreign governments, or direct transfer. Many of our allies who are approved for FMS can purchase the aircraft

Special Programs and Uses

There have been many aircraft in the military that are used for tactical roles in the military.

There are a few private companies that use CH-47 helicopters for firefighting duty, and several companies have done the same with C-130. Also, firefighting lead aircraft often use surplus aircraft like the OV-10A Bronco, although twins like the C-12 Huron/King Air make an excellent lead aircraft. 

Environmental and Economic Impact

Aircraft use enormous amounts of raw materials in their construction, so any opportunity to reduce consumption through keeping airworthy aircraft in storage is a win. The process is very neutral. Fluids are removed, as are anything else that could be caustic, so it is basically just a shell sitting in the sun. 

Economically, it is a win since bringing back aircraft into the fleet as needed is still much cheaper than producing new aircraft, and it is more environmentally sustainable. 
Finally, when an aircraft is scrapped, it produces tons (sometimes hundreds of tons) of metal that can go back into the global supply. 

Clemens Vasters from Viersen, Germany, Germany, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

Parting Thoughts

The boneyard has been around for a very long time, and it will live on as the premier place to park jets that are either no longer needed, fleet reductions, or are otherwise no longer needed for fleet use. One of the benefits is that parts are reintroduced into the supply chain for that particular aircraft type, which is very important considering the average age of a military aircraft. 

At Greenwood Aerospace, we have over four decades of experience working with the U.S. and Allied Nations on numerous global projects. We offer FMS sales and support services, and have a proven record of efficiently handling FMS projects from start to finish. 

It can be difficult to coordinate all of these moving parts. The aviation landscape is made up of parts suppliers, logistics channels, and maintenance consultants, but it can be difficult to connect all the dots to form a comprehensive package. 

That’s where Greenwood Aerospace gets involved. As a leader in military and defense contracting, our team can deliver the logistical support and coordination you need. 

Contact [email protected] to learn more about what Greenwood Aerospace can do for you.