Somewhere between the pilots who commit gear-up landings and the nonpilots who scoff at them are the investigators who must assign blame, if any, and recommend ways to avoid the problem in the future. This may be the toughest job of all, especially where human factors are concerned.
The good news about gear-up mishaps is that they occur on runways, at relatively low speeds, at the end of approaches perceived as normal up to that point. As a result, they rarely lead to serious injuries or fatalities. This inherent survivability allows us to hear directly from the parties involved and gather more than the usual amount of detail about the chain of events leading to them. Often we hear from pilots in reports filed with NASA's Aviation Safety Reporting System. Gear-ups are natural candidates for ASRS reports because they are inadvertent incidents that could result in certificate actions against the pilots involved. ASRS reports, with their incentive of immunity against certain certificate actions, prompt pilots to share their thoughts on mishaps so others can learn from their experiences and be wary.
The reports are as varied as the people who file them. Some ASRS filings are frank confessionals that face up to reality and try to spare others the same pain through thoughtful reflection. Others are lawyer-type briefs that bob, weave, and obfuscate until the bitter end. Some are reticent in the extreme. "On climbout, I noticed my left engine getting hot. So I feathered the left engine and returned....After landing it appears there may have been a cowl plug from my aircraft on the runway. This could have been a factor." What happened in the interval between that climbout and that landing was harrowing in the extreme - but more on that later. The better reports are worth study because they give us important clues as to how to avoid being snared in the same trap.
A charter pilot in Alaska was nearing his destination in a twin-engine Piper Navajo. The pilot was used to certain minor malfunctions with the airplane's stall-warning system, and this led to the trouble that followed, according to the ASRS filing. "I placed the aircraft in landing configuration (with exception of the gear) in preparation for landing. On final approach, I heard a warning horn but thought it was the stall warning horn. After checking the airspeed, attitude, power setting, and reassessing my approach path, I determined that a stall was an unlikely event and continued the approach to its unfortunate result - a gear-up landing. The reason I had concluded that it was the stall horn and not the gear horn was that I had been flying through rain showers and the stall vane will sometimes leak and short out, giving a false indication."
Yes, I can hear you all saying, but the landing gear system includes a position switch and a set of lights, either shining red when the gear is unsafe or green when it's down and locked. What about that?
The pilot's report continued: "I probably missed the gear handle position and the three green lights in my quick assessment because I had an approach plate clipped to my yoke blocking my view. I normally put the gear down abeam my landing site or earlier. My prelanding check consists of pointing at the items on my checklist to check their positions. Neither of these items was completed."
Candid enough, certainly. The pilot's preoccupation with the aircraft's tendency to falsely advertise an imminent stall - a concern which diverted his attention from the prelanding checklist - may have triggered this event. It was certainly distracting. If nothing else, this argues strongly for the prompt resolution of even the most minor maintenance items, even if they seem unlikely to ever enter the causal chain of an accident. The National Transportation Safety Board gave no weight to this mitigating factor in its report, which determined the probable cause of the accident as: "A failure of the pilot to follow the aircraft checklist, and an inadvertent wheels-up landing."
Another Navajo, another distraction, and another wheels-up landing in Alaska - almost. Although the props had already contacted the ground, this pilot made a go-around and made a more successful landing. During the arrival phase, the pilot had spent time communicating with other traffic, verifying that no conflict existed, and discussing a radio frequency used to control lighting. Upon arrival at touchdown height, the pilot of this airplane "sensed the landing gear was not taking the aircraft's weight. This was followed by uncharacteristic noise (blade strike) and a confirmation of three green lights not showing. A go-around was immediately executed and landing made without further problems."
In the meditations that followed, this pilot also had some thoughts on the aircraft's design features. And here again, there was the suggestion that at least one system was not working properly. "Audible gear-unsafe horn was not heard, and a higher throttle threshold setting (for warning-horn activation) would have assisted or, if there was additional link to the flap setting. Low prominence of placement of landing gear lights on (the) instrument panel (one light always obscured by gear handle) was a factor in recognition of (the) problem. Although having called clear, the time of day and overcast sky took extra time in (identifying) the other aircraft being clear of the runway."
For the armchair observer, it's easy to debate the relative merits of these pilots' observations. We can discuss the cases ad infinitum and assign any weight we wish to the possible causes. But if we are wise, we will study the testimony and see the reflection of someone we know well in the proverbial mirror. We can also see that what we put into our preparation for flight often correlates directly with what we get out of it. And this raises the ever-present question: Can you cope with the "realistic distractions" for which we are presumed to be trained? Do you make a careful preflight inspection as a matter of course, knowing that the simplest walk-around is the strongest link to the safety of the proposed flight?
The terse nature of the ASRS account of the cowl-plug incident, in a twin-engine Piper Aztec, gives no clue as to how that simple lapse immediately snowballed into a flight marked by a single-engine instrument approach, a failure to extend landing gear, a botched one-engine go-around, a stall, and a crash. Quoting the official report, once an engine began to overheat, "the pilot shut the engine down and returned to the airport. During the instrument approach the pilot attempted to extend the landing gear and flaps. While [the pilot was] on a one-mile final approach, the tower advised the pilot to go around because the landing gear wasn't fully extended. The pilot said the airplane was past mid-field before he applied power to go around. He said the airplane continued to descend prior to entering a stall/mush. The airplane crashed into a taxiway and slid onto a grass area. The on-scene investigation revealed no anomalies with the normal and emergency hydraulic systems."
The only anomalies known to have existed were in the conduct of the preflight inspection when the pilot failed to remove a cowl plug. The NTSB acknowledged this in its determination of a cause. Whether this resulted in any penalties against the pilot may have depended on the immunizing effects of an ASRS report. But the best product of that report, and the thousands more available for study by any pilot, is the insight it offers into how extraordinary incidents and accidents usually arise from the most ordinary causes.
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