Accident Analysis: Just too much

Nevertheless, otherwise rational aviators persist in the delusion that wishful thinking and willpower somehow blur the relationship between thrust, airspeed, lift, and weight. Getting it through the doors does not mean you’ll get it off the ground.

The industry deserves a bit of the blame. A famous 1970s-vintage ad demonstrating that an upright piano could be loaded into the cabin of a Piper Cherokee Six didn’t go out of its way to mention that at 300 pounds, the spinet weighed less than the passengers who might have occupied that space. More culpability probably rests with reluctance to make difficult decisions about what to leave behind—and a faulty understanding of the performance data in the pilot’s operating handbook.

Performance’s dependence on conditions has lured some pilots into a habit of stretching the envelope.A maximum gross weight of 2,500 pounds doesn’t mean that an airplane will take off loaded to 2,500 pounds. It means that it can take off loaded to 2,500 pounds provided its tires are correctly inflated; its engine produces full rated power; and density altitude, winds, runway length, and surface conditions are all within the parameters specified in the handbook. Piloting technique must also be near perfect if any of these factors is even close to those limits.

The margin for error built into those tabulations is another source of misunderstanding. No, an airplane that can fly at 2,500 pounds won’t fail to break ground if you toss in another box of Kleenex—but keep adding stuff, and at some point there’s too much. Do you really want to find out where?

Performance’s dependence on conditions has lured some pilots into a habit of stretching the envelope. It works until the day it doesn’t. An Alaskan family routinely hauled building materials to their lodge in their cargo-pod-equipped Cessna U206F. With the cabin packed so full that witnesses couldn’t see where the passengers might sit and the tires squashed almost flat, the airplane struggled to an altitude of 150 feet before descending into a vacant automobile dealership in downtown Anchorage and catching fire. It was, at a conservative estimate, loaded at least 660 pounds above maximum gross weight. A mechanic told investigators he saw the pilot fly in what he believed to be an overweight condition on four or five occasions. Presumably the pilot didn’t jump to that loading all at once, but built it up incrementally—since everything worked last time, we can toss in a little more.

While the pilot didn’t secure that cargo, believing there was nowhere for it to shift, at least most of the passengers had seats. (A 4-year-old riding in his mother’s lap was killed.) Not only was the Cessna 180 in another high-profile Alaskan accident packed with tools, groceries, six 5-gallon jugs of diesel fuel, and a 150-pound cast-iron stove, but its pilot refused to reinstall the right seat, making his passenger ride on an ice chest. They made it 37 miles before crashing into a hillside—but the 180 was “only” 300 pounds overweight.