Could a runway include a safety device to destroy a plane's landing gear?

Question

The NTSB recently released its final report of a crash at Hanscom field (KBED) in Bedford, MA. The short of it is that the pilot tried to rotate with the gust lock engaged, preventing the plane from lifting off. It rolled past the runway and finally crashed into a ditch, where it burst into flame, killing everyone on board. (I should say that although I've flown in a small 4-seater a few times, I'm not a pilot — so please forgive me if I misused some terminology.)

One thought I had is that if the landing gear had been destroyed at the end of the runway, the crash could have been a lot less severe. In particular, I was thinking that a small wall could have been designed to knock the gear out, making the plane start skidding on its belly and presumably coming to a stop much sooner. It wouldn't be exactly safe, but it seems like it would be safer than relying on just the gear's braking power.

Does such a device exist at any airports? And if not, has it been considered and rejected for some reason?

Answer 1

There is indeed such a system installed at some airports. It is called an engineered materials arrestor system (EMAS). Incidents such as Southwest 1248 have shown the potential safety issues of runway overruns, as you have pointed out. The EMAS solution uses a pad of special material at the end of the runway, designed to allow landing gear to sink into the material. The landing gear is not ripped off, but as the gear travels through the material, the plane is slowed down.

Destroying the gear is not a desirable option. Although the gear on airliners is designed to safely separate from the aircraft, there is still the potential for damaging fuel tanks or other structure. The aircraft will also be even less controllable after the loss of landing gear. If a small aircraft is not going very fast, a small wall could cause it to flip over, worsening the situation.

In the crash you referenced, the aircraft was traveling very fast at the end of the runway, and an EMAS may not have been sufficient to stop the plane. An EMAS typically has a max entry speed of 70 knots, so in incidents like the one linked from the question, this kind of system may not completely prevent a fatal incident. Since the aircraft's gear must break through the material, lighter aircraft may not be stopped as effectively. However, small aircraft have been stopped with such a system.

The FAA is looking at places where these systems could be useful, with a focus on runways that cannot have the recommended 1,000 foot safety area at the end. The runway safety area (RSA) is the best option for a safety buffer at the end of a runway, providing extra distance for an aircraft to stop. The article above notes that the EMAS at Burbank airport took $4 million to install, and that is a fairly small airport that doesn't usually see anything larger than a 737. Any overrun will incur certain recovery costs, but an EMAS will need to be repaired after any overrun or accidental damage, possibly closing the runway, and will be less effective until repairs are completed. Airports must weigh all of their options for providing a safe facility.

Answer 2

The short answer is yes; EMAS and other arresting systems up to and including nets are in place at many airfields of varying sizes. The most common AFAIK is a gravel pit, aka the litterbox; it's filled with sugar sand, a lightweight gravel like pumice rock or a manufactured alternative, that yields and/or crushes much like EMAS panels under the weight of landing gear to increase rolling resistance and stop a plane that rolls off the end of the runway. They are not designed to damage the plane such as by snapping the gear off (though such damage is often par for the course), as that would actually take away the plane's most effective stopping method, its brakes and rubber tires, instead forcing the plane to skid to a stop on its slick underbelly. They're also definitely not designed or intended to stop a plane barreling off the end of the runway under full engine power.

There is no safety mechanism in existence that can 100% replace the human brain in ensuring safe performance of inherently dangerous tasks. In the accident you refer to, several basic yet critical checklist steps were skipped that would have indicated the presence of a gust lock, among them visually inspecting and checking for free movement of control surfaces during the walkaround, and the stick/rudder movement check during runup to ensure the flight controls are unhindered and properly manipulate the control surfaces. The NTSB places the blame for this accident squarely on the failure to perform basic preflight checks prior to the attempted takeoff. Preflight checks exist for this exact reason; to prevent pilots attempting to fly a plane they will not be able to operate safely due to some mechanical defect or hindrance, whether that's a gust lock, water in the fuel tanks, a bird nesting in the engine cowling, or a bullet hole in the rudder. The walkaround is literally the first thing a new civilian pilot learns on their first flight.

There really is no such thing as a foolproof system; fools are too ingenious. The pilot(s) of an aircaft are ultimately responsible for the safe operation of that aircraft, because it's ultimately their lives depending on a safe flight. That's why it's part of their job to do the preflight checks. If a pilot doesn't value his own life enough to do something as basic as this, he shouldn't be anywhere near an aircraft, because when his lack of regard leads to the loss of his life, it's very unlikely his life will be the only one lost.