Southwest Airlines Crash Landing: Key Questions Remain

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A Southwest Airlines flight, which originated in Nashville, remains on runway after a crash landing at LaGuardia Airport.

There is a lot left to be explained about Monday’s crash landing at New York’s La Guardia airport of a Southwest Airlines Boeing 737. The one detail so far revealed by the National Transportation Safety Board is that the airplane’s nose wheels collapsed rearwards with enough force to push upward into the fuselage and damage the electronics bay.

But what investigators most urgently have to establish is: Why did the gear collapse without the pilots having advance warning that it was faulty?

There is all the difference in the world between an airplane making an emergency landing because the pilots already have been alerted that the nose gear may collapse on contact with the runway – the most common kind of this fairly rare event – and when that happens, as it did at La Guardia, without prior warning.

Crucially, the passengers were not prepared for a crash landing and in the brace position; the airport had not been able to clear and prepare a runway for an emergency, with fire trucks at the ready; and other flights had not been held off. When pilots are on final approach and lower the landing gear they have to confirm that it is “down and locked.” If it is not, they abort the approach, inform the tower, and climb into a holding pattern to burn off fuel, to reduce weight and the chance of fire on landing, and only when the airport is prepared for them do they make another approach.

The Southwest Airlines 737 skidded down the runway at well over 100 mph and finally came to rest on a grass area between runways. Pilots often compare landing at La Guardia to landing on an aircraft carrier—the runways are only 7,000 feet long compared to an average of 10,000 feet as well as running close to water and to each other. The careening 737 could easily have encroached on another runway, endangering other airplanes.

Normally, the nose gear has to take far lighter impacts than the main gear—the main gear hits the tarmac first and takes the maximum loads, and the nose then settles to stabilize the direction of the landing; the nosewheels are also used to steer the airplane from the runway. With the nosewheels gone, the airplane is basically impossible to steer.

The 737’s main landing gear has an unusual characteristic. Its design dates from the first models of the 737 that flew in the 1960s. Even though much of the design has been updated since then, the main gear remains shorter than later model Boeings, meaning that the fuselage sits closer to the ground.

As the 737 evolved from the 1960s through to the present, its engines have become larger. With each increase in size, the clearance between the nacelles hanging beneath the wings housing the engines and the ground has become less. This means that if the nose gear fails and the nose of the airplane hits the tarmac, the engine nacelles can also come into contact with the runway as sparks are spewing from the friction of the crash.

The next model of the 737, the 737 MAX, due to fly in 2017, has even larger engines. Because of this the nose gear has been redesigned and slightly extended to provide more clearance. But the fact remains that the original 1960s configuration inhibits the extent to which 737 can adapt to larger and more fuel-efficient engines—and maintain a safe gap between them and the ground.