Accident report: Frozen-lake fever

Winter flying is a tonic for pilots, too, provided they adapt safely to the challenging conditions of a changing and sometimes extreme environment. When they don’t give this obligation its due, the perils of impulsive decision-making and risky maneuvering increase—sometimes beyond the point of recovery, as the examples of a botched buzz job over a friend’s place and a trouble-plagued touchdown while landing on a frozen waterway to socialize with a group of ice fishermen bear witness.

Light aircraft pilots love calm, windless conditions, but hazards may still abound. Take flat-light conditions: When lighting and/or snow-covered ground obscure terrain features, an illusion may be created that gives the pilot the impression that the aircraft has more terrain clearance than it actually has.

A Cessna 170B pilot was returning to a private airport in New Hampshire from a brief cross-country with three passengers aboard on December 22, 2007, when, according to a National Transportation Safety Board accident report, a decision was made to deviate from the arrival and “make a low pass over an adjacent lake, near a friend’s property.”

Often prelude to trouble, the decision to maneuver down low ended the flight then and there, although fortunately, without injuries: “The pilot said that his depth perception was negatively affected due to the flat light and snow on the ground. While maneuvering over the lake, the right main landing gear contacted the snowy frozen surface, which resulted in the right wing impacting the surface,” the report said.

Although the NTSB said the probable cause of the accident was the 1,700-hour, 48-year-old pilot’s failure to maintain clearance from the frozen lake while maneuvering, it noted the contributing influence of “unfavorable lighting conditions,” which, as reported at an airport 10 miles away, included calm winds and an overcast at 2,200 feet.

Not every airplane that ends up scuffed and stranded on a frozen lake winds up on the surface by chance. Landing an aircraft on frozen water bodies is not an uncommon winter pastime and in some places takes the form of scheduled entertainment for ski-equipped aircraft or airplanes still rolling through the season on regular aircraft tires or large tundra tires.

Seven days after the flat-light incident in New Hampshire, the 62-year-old, 1,800-hour pilot of an older model Cessna 172 dropped in on a frozen lake in Crystal Falls, Michigan, to socialize with a group of ice fishermen.

So far that day, the NTSB reported, the pilot’s outing had been going well: “He stated that he had landed at one end of the lake and spent about 20 minutes talking to some fishermen and then got back in the airplane and flew to the opposite end of the lake. Upon landing, the nose landing gear struck a crack in the ice and collapsed. The airplane then slid about 400 feet before coming to rest. Examination of the airplane revealed damage to the engine, propeller and firewall.”

The pilot was not injured in the accident, of which the probable cause was determined to be the “rough, unsuitable terrain encountered during the landing” that resulted in the failure of the nosewheel.

Would you recognize flat-light conditions in a forecast or upon encountering them in flight, and be on guard for the kind of optical illusion they can induce?

What technique would you use for landing on a frozen lake? How much information about existing surface conditions or obstructions at an off-airport destination, and what level of personal proficiency and aircraft familiarity would satisfy you of the safety of conducting the flight?

It is no illusion that these are weighty questions to answer before putting yourself—and perhaps a planeload of trusting passengers—into a slippery situation.

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