By Thomas P. Turner
There are those who have, and those who will. If youve eventhought about checking out in a retractable-gear airplane youve probably heard this glib saying about gear-up landings.
The accident record dramatically reinforces the unfortunate fact that about half of all mishaps in retractable-gear airplanes involve the landing gear. Its no wonder some people consider landing gear-related mishaps an inevitable part of flying retractable-gear airplanes.
In fact, landing gear-related mishaps – any accident where the landing gear is a significant factor – happen more than eight times a week on average in the United States to factory-built piston airplanes.
Although they almost never cause serious injury and often only minor damage as defined by FAA/NTSB reporting standards, LGRMs are costly. The average minor damage gear-up landing costs about $40,000 to fix in single-engine piston airplanes. The same mishap in a piston twin can cost $60,000 or more to repair. It may take months to get the airplane flying again, and a gear-related accident can render a pilot virtually uninsurable for up to five years following the mishap.
How many $1,500-a-year policies do you think an insurance company has to sell to cover the more than 400 LGRMs that befall certified, piston-engine airplanes every year? In fact, the likely $25 million-plus annual cost of gear-related claims makes insurance costlier for everyone, even owners of fixed-gear airplanes, as the insurance companies increase premiums to cover these frequent and expensive claims.
There are three types of landing gear-related mishaps: The classic oops, I forgot gear-up landing, where the pilot simply did not put the landing gear down before touchdown, gear collapse events, where the pilot put the gear down but for some reason it did not remain down on the ground, and gear problems resulting from mechanical causes, where some identified system failure prevented proper gear extension and lock-down.
In calendar year 2002 there were 874 FAA mishap reports involving certified, piston-powered retractable-gear airplanes in the United States. Of those 431 – 49 percent of all accidents – were LGRMs. Of those 431 gear-related reports, 208 (48 percent) were gear collapse mishaps, 158 (37 percent) gear up landings, and the remaining 65 (15 percent) involved an identified gear-related mechanical cause. Note that cases where the gear failed after a hard landing short of the runway or off-airport are not included, nor are excursions from the prepared runway surface that ended up with a collapsed gear. In short, these are accident in which the gear was a cause, and not simply collateral damage.
Arent Those Numbers High?
If you think those numbers sound higher than reported elsewhere, thats because most reports on aviation accidents come from the records of the National Transportation Safety Board, while these data come from the FAAs preliminary reports. NTSB data does not reflect this epidemic of LGRMs and vastly understates the true number and nature of airplane mishaps.
Thats because NTSB rules require pilots to report an aircraft accident or incident to the NTSB. By NTSB definition an accident is an occurrence … in which any person suffers death or serious injury, or in which the aircraft receives substantial damage.
The NTSB further defines substantial damage as damage or failure which adversely affects the structural strength, performance or flight characteristics of the aircraft. An incident, according the NTSB, is an occurrence other than an accident … which affects or could affect the safety of operations.
But the NTSB also says that damage limited to … bent fairings or cowling, dented skin, small punctured holes in the skin …, ground damage to … propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes or wingtips are not considered substantial damage….
By definition, then, most LGRMs are specifically exempt from the reporting requirements and therefore are not included in most aviation safety studies. Only the FAA preliminary reports, which appear on the FAAs web site for two weeks following the report and are then purged, give an accurate picture of the true number of light plane mishaps – and the whopping percentage of all accidents that are LGRMs.
Landing gear-related mishaps dont happen in a vacuum. With the exception of the truly mechanical causes, gear up landings and gear collapses usually happen when the pilot is faced with outside distractions. The contributing factors in most LGRMs can be boiled down into a fairly short list:
Flight instruction. A disproportionate number of LGRMs happen with during dual flight instruction, when two brains and two sets of hands and eyes fail to prevent the LGRM. Its common when receiving instruction to delegate (consciously or not) responsibility to the instructor pilot. Pilots getting training or flight reviews often behave differently than normal, thinking they have to act differently while under observation or evaluation. And although instructors dont like to admit it – its easy to get complacent, especially with an experienced pilot in the left seat – and fail to step in when gear discipline demands.
Touch and goes. Gear collapse accidents very frequently happen when the pilot is flying touch-and-goes. About half happen with an instructor on board. Theres so much to do in the very short time on the runway during a touch-and-go that retract pilots frequently move the landing gear switch instead of the flaps – with predictable results.
Cleaning up. Many training airplanes recommend retracting flaps as soon as the airplane touches down, which reduces landing distances. Many pilots carry that technique into retractable-gear airplanes. As in the case of touch-and-goes, though, the mishap record is flush with stories of pilots inadvertently pulling on the gear handle instead of the flaps. Usually the nose wheel folds up and the engine(s) and propeller(s) drop expensively onto the pavement.
Open doors or windows. Another common contributing factor is the noise and distraction of an open door or window. Although open cabins rarely affect flying performance significantly, the noise level can be overwhelming, especially to the pilot who has never been trained in this scenario. All too often the pilot is so distracted by the open door (and perhaps the reaction of passengers) that he or she forgets to lower the gear prior to landing.
Wind. Strong or gusty surface winds are frequently cited in LGRM reports. After the airplane turns final into a strong wind, its ground speed and angle of descent may make performance look like the gear is down when its not.
Electrical failures. Most landing gear systems have at least some electrical component, whether the gear is totally electric or uses an electric motor to power a hydraulic retraction system. More often than wed hope, the FAA preliminaries report a pilot who landed gear up after a total electrical failure, either unaware theres always a manual landing gear extension procedure as a backup, or sometimes only partially completing a manual gear extension because of unfamiliarity with the system.
Technology At Work
Classic risk management theory tells us the best way to avoid accidents is to remove the cause. Although some airplanes (notably the Cirrus SR22) now obtain retract-like cruise speeds with fixed landing gear, negating the sole advantage of retractable gear, there will always be retracts in the fleet – and you know Cirrus has to be at least thinking about how a retractable SR22 would perform.
With retracts here to stay, you might turn to training as the answer. However, pilot experience does not seem to be much of a factor in LGRMs. High-time pilots may suffer from complacency that negates the advantage of experience.
Safety engineering holds that if you cant eliminate the hazard altogether, you should design safety systems to prevent accidents. Most retracts have several technological aids designed to prevent gear-related mishaps.
Almost all retracts have a gear warning horn. Usually, if the throttle is pulled to idle but the gear is still up, a warning horn will sound. Some late-model airplanes rig the horn to sound when flaps are fully down but the gear is up also; many include a flashing annunciator light on the instrument panel. The beep-beep-beep of the gear horn is designed to be distinctive from the steady tone of the stall warning.
Unfortunately, the gear warning system doesnt seem to prevent gear-up landings. Many pilots report hearing the beep-beep-beep before that awful scraping sound, but not recognizing the warning in time. Many pilots of light twins get accustomed to hearing the horn during engine-out training, ignoring the warning when its needed for real.
Its also common instructor practice to pull the warning horn circuit breaker to shut off the alarm – but sometimes the MEI forgets to reset the breaker, contributing to a later mishap.
Since the warning doesnt always get the pilot to extend the gear, designers have also played around with mechanisms that would just lower the gear rather than sound a warning. Piper built Arrows and Lances with this system for several years.
The system automatically extends the landing gear if the throttle is at idle and the airspeed drops below some figure. However, this proved to be a less-than-perfect solution. Theres also the danger of a stall if the gear automatically drops following an engine failure or other emergency. In fact, the FAA once mandated the disconnection of Piper autoextend systems in the wake of a gear-and-stall-related crash, but the AD was later rescinded.
Other technological solutions involve switches that prevent retraction unless the throttle is advanced sufficiently or that prevent retraction if theres weight on the gear.
The throttle switch is designed to prevent inadvertent retraction during a touch-and-go. The record suggests that even this simple technology doesnt completely work to avoid gear collapses.
Squat switches, which are almost universally installed on retracts, interrupt electrical flow to the retraction mechanism and prevent gear retraction when theres weight on the wheels. But the gear collapse record shows that even squat switches arent always effective.
I was able to see this for real in a Beech Baron, equipped with dual squat switches (one on each main gear). That Baron also has a BF Goodrich Skywatch traffic avoidance system. To prevent constant traffic alerts while taxiing around other airplanes on the ground, the Skywatch is wired into the gear squat switches so that it goes into standby mode when the Baron is on the ground.
One day I asked a front-seat passenger to tell me exactly when the Skywatch went to standby mode after landing. The company assured me there is no delay built into the standby feature, which means the Skywatch would tell me the point in the landing roll when at least one squat switch engaged.
I found repeatedly that the squat switch does not engage until the end of the landing roll, when the airplane slows to a walking pace taxi. At least in this one airplane, the squat switches would not prevent an inadvertent gear retraction caused by hastily cleaning up during the landing roll or reconfiguring for a touch-and-go.
The LGRM record suggests squat switches are ineffective in preventing gear collapse in the fleet as a whole.
Some models of airplane have a reputation for landing gear-related mishaps. Critics are quick to point to models of the Beech Bonanza and Baron that have the gear handle on the right of the throttle quadrant and the flap switch on the left – exactly the opposite of the convention most manufacturers use. Transitioning pilots can move the wrong switch, or move the gear switch at the wrong time, because the gear switch is where they expect the flaps to be.
Sure, there are lots of Beech LGRM reports in the FAA record. But it seems that may be more a factor of the sheer number of Bonanzas and Barons in the fleet, and not a problem related to gear switch placement.
At 43 percent and 46 percent LGRMs for the Bonanza and Baron, respectively, the Beech record is actually far better than the 60 percent in Cessna 210s, 70 percent in Cessna 310s and 320s, the 52 percent in Piper Comanches, and 55 percent in Piper Senecas. Further, the Piper Apache/Aztec airplanes (which also have backwards gear handle placement) have one of the lowest rates of LGRM among popular retracts. Therefore the location of the gear switch alone does not appear to be a major factor in landing gear-related mishaps.
If retractable landing gear systems and safety devices cant protect you from a LGRM, its up to you to do it yourself. Luckily, mishap history tells us some things we can all do to avoid adding to the statistics.
Admit theres a threat. Dont forget that anyone can have a bad day, and that many bad days are manifested by a LGRM.
Learn your system. Make sure you know how your landing gear system works. Include a practice manual landing gear extension in your next flight review, if not before. Read the POH and practice manual gear extension for every make and model retract you fly because few systems are identical.
Train to proficiency. Most retract checkouts dont spend nearly enough time on gear extension discipline. You tend to do things the way you first learned them, which for most pilots means flying a fixed-gear airplane. A retract checkout needs to provide enough practice so the Law of Primacy is replaced by the Law of Exercise – you remember most what you practice the most.
Three times around the field for an RG checkout obviously doesnt cut it, given the LGRM record.
Overcome distractions. If the wind is strong and gusty, a door or window has popped noisily open in flight, or any of a multitude of other distractions robs your attention, remember that well-practiced procedures, backed up by reference to checklists, will help you prevent a LGRM.
Dont clean up until youre stopped. Many, many gear collapses result from inadvertent gear switch movement during the landing roll. Get in the habit of touching nothing until youve completed your landing. Come to a complete stop on a taxiway where you have time to properly identify a switch before you move it.
Swear off touch and goes. Make all your retract landings to a full stop to reinforce the discipline of stopping before you reconfigure the airplane.
The appalling LGRM rate erodes the aircraft population and is extremely expensive in repair costs and airplane downtime. It adds to the cost of airplane insurance for everyone, and can make the offending pilot miserable for years. We all know the phrase there are those who have, and those who will. Its up to you to ensure youre one of those who wont.
-Thomas P. Turner is head of Mastery Flight Training LLC, which provides aviation safety and instructional materials for major universities and airplane owners groups.