All three occupants of a Cessna 172M lost their lives on November 16, 2012, when the aircraft collided on takeoff with a pickup truck that was crossing Runway 31 at Maine’s Knox County Regional Airport. The collision, in gathering darkness, between the Cessna and the truck—described in a preliminary NTSB accident summary as a “non-airport vehicle”—sheared off the Cessna’s right elevator and other parts of the horizontal stabilizer. Witnesses said the aircraft appeared to climb in a “chandelle” type maneuver and with a high angle of attack to the left before descending nose down into terrain 2,200 feet from the initial impact point.

The pickup’s driver and owner was a 62-year-old pilot employed by a company based at the airport. He told investigators that while holding short of the runway, he “announced his intentions on the common traffic advisory frequency using a radio in his vehicle, heard no response nor saw anything on the runway, and he proceeded to cross Runway 31. He saw something grayish in color, but continued to cross the runway, and then got out to inspect what he saw at which time he observed an airplane attempting to climb. He continued watching the airplane drift to the left of the runway and make a left turn as if attempting to return to the airport. Subsequently, the airplane was then observed in ‘slow flight’ and then it began to ‘spin.’” News accounts reported that the truck lacked a beacon-type light that an official vehicle on an airport might possess.

The 24-year-old private pilot of the Cessna, an engineering graduate student, and his two undergraduate passengers had departed from Bangor International Airport in the aero club aircraft for a sightseeing flight earlier in the day. The accident, which was a devastating blow to the close-knit university and airport communities to which the parties belonged, focused media attention on nontowered airports and how access to movement areas by ground vehicles is managed.

Months before a final NTSB report would offer a probable cause, airport officials began to discuss possible changes to ground-vehicle policies at the airport. Some hangars are located on the opposite side of the two-runway airport from the main facilities. The airport diagram depicts a crossing point just beyond the fixed-distance markers 1,000 feet from the departure end of the precision instrument Runway 31. The FAA’s advisory circular (AC) Ground Vehicle Operations on Airports “strongly recommends that all certificated airports [typically only those with commercial service] provide initial and annual recurrent driver training to all persons with access to the movement area.”

The AC also provides a sample training curriculum and training manual. A set of recommended vehicle regulations includes a provision proposing that “vehicles operating on the movement area shall be equipped with operating amber rotating beacon or equivalent.”

If a rare set of conditions conspired to allow a collision between an aircraft and a ground vehicle to occur within the contained environment of the “airside” premises of an airport, pilots should be at least as wary in the more vulnerable regions of the airports they use—especially at unfamiliar destinations.

A Cessna 172S being flown on a solo cross-country by a student pilot struck an automobile on an adjacent road as it was landing on a 3,500-foot-long, 40-foot-wide runway with nonstandard markings at Texas Northwest Regional Airport.

“The student pilot stated that just after crossing the fence the landing gear impacted the automobile, resulting in a hard landing. The nose and left main landing gear collapsed, and the airplane veered off the right side of the runway before coming to rest in the grass,” said the NTSB’s preliminary accident report.

Pilots tend to think of runway incursions as typified by one aircraft transgressing on space rightfully claimed by another, such as a disoriented pilot straying onto an active runway while taxiing. But as these two preliminary accident accounts remind us, ground vehicles with access—official or otherwise—to airport movement areas can become involved in conflicts as well. Just as obviously, radio communication is not a panacea.

Many airport diagrams depict “hot spots” where a confusing layout, or a history of conflicts, is brought to a pilot’s attention during preflight preparations. But in the absence of history or airport complexity, don’t ignore the need to study even the simplest airport diagrams for places where conflicts could arise.

Dan Namowitz is an aviation writer and flight instructor. He has been a pilot since 1985 and an instructor since 1990.

Complexities

Why accident data don't talk about gear-up landings

David Jack Kenny

One little-known quirk of GA accident statistics is that they exclude most gear-up landings. This seems odd, since repair costs start at maybe $25,000 in the best case (a low-powered single that escapes major engine damage) and can easily pass $150,000 for a pressurized twin.

With the used aircraft market still depressed, fixing the damage may cost more than the airplane is worth, with the result that gear-ups probably are one of the leading reasons older airplanes get scrapped. (Only the insurance companies know for sure, and so far they aren’t telling.) However, a careful reading of Part 830 shows that its definition of the “substantial damage” that requires an NTSB report specifically excludes “bent fairings or cowlings, dented skin, small punctured holes in the skin or fabric, ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wing tips.”

Of course, engineers do their best to protect us from ourselves. The most common safeguard is a gear warning horn; if the throttle is closed (or, in many airplanes, flaps are extended past the first notch) with the gear still up, it honks to alert the pilot. This system has its weaknesses. The horn usually isn’t wired into the audio panel, and several pilots have reported that noise-cancelling headsets can make it difficult or impossible to hear. If headwinds or a low, flat approach require landing with some power, the microswitch triggered by throttle position may stay open. And because twin-engine trainers spend so much time with one engine idling or shut down, some have a switch that disables the horn. Opening the throttle or lowering the gear resets it—but that won’t help if you forget the gear on a single-engine approach.

Not forgetting is the best solution. That means rigorous adherence to written checklists or at least cockpit flows (GUMPS check). Gear-ups are likeliest after some interruption breaks that flow. For example, to improve glide performance, one commercial student routinely left the gear up until final on 180-degree power-off spot landings. When a tower controller warned them it was up, his CFI explained—after which both pilots forgot to put it down.

David Jack Kenny is grateful that his Piper Arrow will extend its own gear if he forgets.