Cheryl Allegretti's husband was a meticulous pilot with more than 20 years experience when the plane he was piloting crashed in a northwest Iowa cornfield, killing him and two passengers, apparently because it ran out of gas.
"It's still hard for me to believe it at all," said Allegretti, of Cambridge, Wis. "Like everybody has told me, he was the most cautious, safety pilot that they ever knew."
National Transportation Safety Board officials say what baffles them is the frequency with which pilots run out of gas. In the past five years, according to the NTSB, fuel exhaustion was the cause or a factor in 238 small plane crashes in the U.S., killing 29 people.
"It's surprising to me that there's a group of pilots who will knowingly push it, thinking 'I can make it the last couple of miles' and come up short," said Tom Haueter, director of the NTSB's Office of Aviation Safety.
There were 8,016 crashes of civilian planes _ a category that excludes commercial and military flights _ from 2004 through 2008, according to the NTSB. Pilot error is blamed in about 75 percent of those crashes, which killed 2,640 people on board.
In accidents where pilots were at fault, 3,909 happened during takeoffs or landings and 1,500 were because of mistakes made during bad weather, according to the NTSB.
Comparatively, the 238 small planes that crashed because they ran out of gas isn't a large number, but aviation experts say it shouldn't happen at all.
"There's a certain group of accidents out there that are inexplicable. You just go 'What are you thinking? What are you doing?' They're hard for us to get a handle on,'" Haueter said. "It seems like it's an easily preventable accident."
The June 23 Iowa crash that killed Frank Allegretti, 64, Thomas Boos, 60, of Fort Atkinson, Wis., and Malcolm McMillan, 65, of Milton, Wis., happened just a few miles from a small airport in the farm town of Sheldon. The men were flying from Wisconsin to South Dakota on a hunting trip.
Witnesses reported that the plane flew low and the engine sputtered before the crash.
When planes run out of fuel, the NTSB usually points to mistakes by pilots _ inadequate preflight inspections, mistaken fuel planning or not checking the fuel caps.
A pilot who crashed his Cessna 205 on June 24 in Porterdale, Ga., told investigators the seals on his fuel caps were worn, so he borrowed fuel caps from a friend's airplane, a Cessna 182.
"The pilot stated he had replaced the seals in the borrowed caps in order to prevent water from leaking into the fuel, but that the new seals did not fit as tightly and that fuel must have been 'sucked' out of the tanks," an NTSB report stated.
Another pilot who refueled during a November 2007 flight down the West Coast had filled up on a slope, leading him to mistakenly believe his tanks were full, according the NTSB. About two hours after taking off, the plane crashed into a citrus grove in McFarland, Calif., killing the pilot and two passengers.
The majority of civilian planes flying date to the 1960s and 1970s and aren't equipped with fuel warning signals, said Thomas Turner, owner of Mastery Flight Training in Rose Hill, Kan. Fuel gauges also can be unreliable because airplanes bounce around in flight, causing inaccurate readings.
Pilots also sometimes take off with less than full fuel tanks because baggage and passengers would otherwise push planes beyond weight limits, Turner said.
Despite all possible factors, Jane Berg, chief flight instructor at Indian Hills Community College in Ottumwa, Iowa, called running out of fuel "probably the silliest mistake that a pilot can make."
Berg, who has 25 years of flying experience, said pilots may miscalculate how long they have been flying or underestimate the winds.
"Or they get home-itis: 'If I can stretch it just a little further I won't have to stop,'" she said.
The Aircraft Owners and Pilots Association, a nonprofit general aviation group, offers about 200 free safety seminars to more than 40,000 pilots a year and repeatedly emphasizes the need to watch fuel levels. It also offers online courses and posts "pilot service announcements" about fuel on its Web site.
Combined with better technology, such as low-fuel warning lights on newer planes, awareness efforts seem to be helping, said Bruce Landsberg, president of the association's Air Safety Foundation.
Fuel mismanagement crashes declined from 167 in 1999 to 76 in 2008, Landsberg said.
It's important to remember that people run out of gas for a number of reasons and that it's easy to criticize in retrospect, said Steve Davis, a pilot with the Des Moines Flying Club.
"I'd like to find a pilot, or the driver of a car, or in a boat that maybe went over a dam, who left his house that morning thinking he was purposely going to run out of fuel," Davis said.