Proficient Pilot

Belly up

December 1, 2005

Capt. Barry Schiff retired from TWA in 1999.

About three times a week, a U.S. pilot finds his airplane impossible to taxi because it is on its belly instead of its wheels.

Many of these embarrassing and costly accidents are the pilot's fault. He forgot to lower the gear before landing, retracted it while on the ground, or raised it too soon after liftoff. Pilots are surprised to learn, though, that 58 percent of gear-up landings are caused by mechanical malfunction and not pilot error.

Last month we discussed the problem of landing with a nosewheel that fails to extend, a topic inspired by the televised landing of a JetBlue Airbus A320 with a nosewheel cocked 90 degrees (see " Proficient Pilot: Nosewheel Landing," November Pilot). This month this column is about problems associated with the main landing gear.

A recent event that also made television news involved a high-wing airplane landing with one main gear leg that would not extend. Its pilot landed on the main wheel that had extended and deftly laid the opposite wing onto a truck racing along the runway in formation. Although this was a marvelous display of skill, I hope that it does not encourage others to try it. One error and such a heroic effort can turn to tragedy.

A pilot can confirm that one or more legs have failed to extend by flying abeam the control tower or requesting that the pilot of a chase airplane move in for a look. Be cautious before undertaking any "formation" flying and be skeptical about these observations (see " Safety Pilot Landmark Accidents: Down and Locked," page 96). The gear may appear to be down but might not be locked down.

Pilots should be able to operate emergency gear-extension systems with ease. One way to gain familiarity with them is to arrange with your airframe and powerplant mechanic to raise and lower the gear using the alternate system while the airplane is on jacks during an annual inspection.

Try not to become so distracted during a landing-gear problem that a more serious problem develops. Maintaining a safe altitude and airspeed is paramount; getting the wheels down is secondary. The stubbornness of landing-gear legs that refuse to extend might be overcome with brute force, which means pulling some Gs. Then, the landing gear is made to weigh a few times its normal weight, and this could force the lagging leg(s) into position. At a safe altitude, descend at maneuvering speed, roll into a steep turn, and pull the needed Gs.

Inducing a strong yaw might be helpful, too. When below maneuvering speed, briskly push the rudder one way, release pedal pressure, and allow the airplane to stabilize. Then yaw the other way and hope that the leg(s) falls into place. If all efforts fail to stiffen the legs, a pilot should land at an airport with crash-and-rescue facilities even though a gear-up landing rarely requires such assistance.

Many believe that a gear-up landing on grass or dirt causes less damage than one on concrete or blacktop. This is not true. A smooth, hard-surface runway usually results in less damage than rough, unimproved grass strips. It does generate sparks that usually are harmless.

While proceeding toward a suitable airport, remember that range will be limited by the increased drag. Consider burning excess fuel to reduce landing speed and fire potential. If the problem is one main leg that fails to extend, consider burning as much fuel from that side of the aircraft as practical. By reducing that wing's weight, you can hold it off the ground longer during the landing.

Should flaps be used during a gear-up landing? Generally, yes, especially on high-wing aircraft to reduce touchdown speeds. An exception is when landing with a misbehaving nosewheel. You can keep the nose off the ground at slower speeds with flaps retracted.

Recommendations for low-wing airplanes are controversial. Flaps obviously reduce touchdown speeds, but landing on the belly with them extended can destroy internal wing structures. Me? I prefer to sacrifice the wings and minimize the risk to passengers.

Prior to a gear-up landing, ensure that passengers are tightly buckled, loose objects are stowed, and everyone knows how to expeditiously and calmly evacuate after the aircraft has come to a stop. Fire is rare but possible. I oppose turning everything off when on short final because this is distracting and precludes the possibility of a go-around. Besides, landing with everything on does not seem to increase the risk.

Failure of the gear to retract after takeoff is not a serious problem unless you are on an IFR departure from an airport with weather below approach minimums. You will have to proceed to another airport with reduced aircraft performance.

Some landing-gear problems can be prevented by thorough preflight inspections. Ensure that the wheel wells are clear of dirt and debris that can impair mechanisms and microswitches.

Although mechanical failures account for most difficulties, recall that many gear-up landings are caused by pilot error. If a pilot notices that something begins to scrape the runway while landing, he should not try to go around. Applying power to a possibly damaged propeller, engine, and airframe can result in a more serious problem. He should instead resign himself to the ride; it will be a short one.

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