September 17, 2015: The U.S. Marine Corps lost 18 personnel in aircraft accidents during the first nine months of 2015, which is a five year high for annual losses. It’s unclear if this is just a statistical anomaly or the result of some underlying problem. The marines must operate a lot of older aircraft and do so intensively. Older aircraft, even with more maintenance and monitoring, are more likely to suffer accidents. The marines cannot afford to replace all of its older helicopters (like UH-1s and CH-53s) and fighters (AV-8B). The vertical takeoff AV-8B has always had a higher accident rate, no matter what the age or what nation was operating it. Despite all this the aircraft accident rate for the marines remains low, at 2-3 aircraft per 100,000 flight hours. Personnel losses are higher for the marines because of heavy use of large transport helicopters carrying lots of marines at night or in bad weather and difficult terrain.

The number of people carried on aircraft makes a big difference. For example, it was only recently that the large U.S. Air Force UAVs (MQ-1 Predator, MQ-9 Reaper, and RQ-4 Global Hawk) got their accident rate down to the same level as manned fighters. This was not news because when a large UAV crashes it does not make headlines, although the loss of such expensive and useful equipment is felt by the military.

It wasn’t until 2011 that large UAVs got their accident rate under 4 per 100,000 hours (3.8). This accident rate was lower than that of the F-16, which was then one of the safest manned fighter aircraft flying.  At the same time the F-22 accident rate was about 6 per 100,000 hours. F-15s and F-16s have an accident rate of 4 per 100,000 flight hours and the F-22 rate has, as expected, come down since then.

Despite the lower UAV accident rate now, the decade previous to that saw heavy losses. Until 2011 some 20 percent of the air force Predator and Reaper UAVs were lost to accidents. This spurred the air force to make UAVs more reliable and reduce the loss rate. By 2010 the accident rate for its MQ-1 Predators was down to about 5 and that continued declining. The year before that the UAV rate was twice the rate of manned fighter aircraft (like the F-15 or F-16) and four times the rate of the old but very reliable B-52. Note that the UAV accident rate is lower than that of single engine private aircraft (8). Reapers have a slightly higher rate than the older (and more numerous) Predator.

At its worst the loss rate for the 1.1 ton MQ-1 Predator was 30. The 4.7 ton larger MQ-9 Reaper had a loss rate of about 15 in 2010, after four years in service. The MQ-9 made its first flight in 2001. The Predator has been in action since the late 1990s. The design and operation of the MQ-9 learned much from the experience of the MQ-1. For two decades engineers sought ways to make these unmanned aircraft more reliable and resistant to accidental loss. It’s been difficult because these aircraft have been flown frequently, in many different climates and under combat conditions for the past decade. Safety features that worked in Iraq often did not work in Afghanistan. UAV operator training had to be tweaked as well. Experienced pilots of manned aircraft often did less well operating UAVs than non-pilots who learned how to fly on simulators. It seems that there were things pilots of manned aircraft had to unlearn before they could handle UAVs more effectively.

One major advantage with the large UAVs was that none of them were suffering from age related problems because so few survived to be “old UAVs”. For the marines the age of their aircraft is a growing problem and it is particularly bad because most of the elderly aircraft carrying marines into combat zones, often at night, in bad weather and in difficult terrain. There is not much margin for error under such conditions.