Depleted Uranium on Commercial Aircraft
Three biggest American airplane manufacturers putting radioactive material on commercial aircraft designed to carry millions of passengers. Sounds improbable, right?
Between 1969 and 1971, three new commercial airplanes took their first flight—the McDonnell Douglas DC-10, the Lockheed L-1011 TriStar, and the Boeing 747. Made by three different American aircraft manufacturers, these planes had one thing in common. All three used depleted uranium material as counterweights.
Why Do Airplane Manufacturers Use Counterweights?
Airplane manufacturers use counterweights to control flight surfaces on airplanes. Without the proper use of counterweights the ailerons, elevators, and the rudder will start wobbling, creating a dangerous elastic motion in the wings and the tail of the airplane. The stresses that this motion creates can rip apart flight surfaces and make the airplane uncontrollable.
Watch what happens to wings and the tail of this glider with no counterweights installed:
In the 1960s and 70s, using depleted uranium as material for counterweights made sense to airplane manufacturers. Depleted uranium has the right density, cheap, and the health risks associated with it were relatively minimal.
Flying on one of these airplanes posed no significant radiation risk to the passengers or the crew, even after many flights. Additionally, a cadmium coating protected the counterweights from leaking toxic material.
When the airplane worked as designed, no problems arose from these counterweights. In fact, it was unlikely that any passengers, or even the crew, realized that the airplane had depleted uranium on board (it is certainly not something that airplane manufacturers cared to advertise). But when airplanes crashed, it seems that investigators were, at the very least, informed about the presence of depleted uranium on-board. But even during crash investigations, there is little evidence to show that investigators were ever concerned about depleted uranium poisoning.
In two notable 747 crashes, one in Amsterdam and another near London, investigators deemed that the public was safe from exposure to depleted uranium, despite the failure to recover all of the material at either crash site.
The Change in Attitude
By the early 1980s, Boeing, McDonnell Douglas, and Lockheed all began producing tungsten counterweights to replace depleted uranium ones. All new airplanes came with tungsten counterweights. Any spare parts ordered contained tungsten as well. Nevertheless, it took decades to completely phase out the use of depleted uranium counterweights.
By the turn of the century, only approximately half of all 747s, DC-10s, and L-1011s owned by US airlines had depleted uranium on board. And because tungsten parts have been used as spares since the 80s, it is likely that most, if not all, of these airplanes are now free from depleted uranium on board. It appears the trend is the same for foreign operators of these planes as well.
With the retirement of Delta’s 747s in late 2017, none of these three airplanes fly passengers any longer. Only a few DC-10s fly cargo for FedEx, and some of the 747s are posed to fly cargo for UPS in the near future. The L-1011’s commercial failure means only a single one is still flying and even then only as a scientific launch pad aircraft for Orbital Sciences.