What might have happened in plane crash that killed Duluth man

The Laramie (WY) Boomerang reports that a Duluth doctor has been killed in the crash of his homebuilt airplane.

The Star Tribune identifies him as former St. Louis County medical examiner Donald Kundel, 79. The Duluth News Tribune says he had recently beaten cancer and was on his way to Laramie to celebrate on a hunting trip with his son.

I know every inch of the type of plane Kundel was flying; it’s the same type of airplane I built.

What happened?

A key may be in the FAA’s description of the crash as occurring under “known circumstances.” ( Update Sunday 3 p.m. – The FAA is making clear it was under unknown circumstances. Original reports used “known.”)That means the pilot had advised air traffic control that he had a problem. What kind of problem is impossible to say. It could be medical — a 79 year pilot flying at altitudes requiring oxygen — or it could be mechanical.

In the latter category, investigators will almost certainly look immediately at the possibility he ran out of fuel, especially since a witness reports the engine had stopped. But witness statements can be notoriously unreliable. And there are lots of things that could make an engine stop. More and more experimental aircraft use electronic ignitions, for example, and one bad alternator can quickly discharge a battery.

The RV-7A holds 42 gallons of fuel, but only about 41.5 gallons is “usable.” A pilot would normally calculate fuel usage when planning such a trip. Here, for example, is what the trip would look like (using the Weathermeister.com flight planning tool) today, given the weather conditions (click far larger view).

kdlh_klar.jpg

There’s a two-gallon penalty for headwinds and, flying west, there’s almost always a headwind.

The above flight plan, however, calculates flying at 7,500. The pilot of this flight flew at 12,500, requiring more fuel to climb to that altitude. There is, however, more fuel economy at high altitudes because of the thin air, which also requires less fuel. The destination was well within the airplane’s capability.

The Aircraft Owners and Pilots Association flight planner says at it’s likely most wasteful setting, a plane would require about 53 gallons, but that assumes a fuel-burn rate which may be higher than what the pilot might have normally experienced. Aggressive “leaning” (adjusting the mixture of gasoline and air) can change fuel consumption by as much as 40 percent. Some RV-7A pilots I’ve talked to have said they use only 5.8 gallons per hour at the higher altitude.

kdlklar_aopa.jpg

The flight’s data, tracked by FlightAware.com, shows that the pilot did not make a fuel stop.

But the flight data doesn’t provide any answers beyond that. The last indicated position was still 20 or so miles away from the airport. The pilot apparently had cleared mountains to the east of Laramie and was descending. Judging by the speed of his airplane at that point, his engine was working.

The first report of the crash came 8 minutes later.

It is possible the plane had “extended range” fuel tanks, which would have provided another 10 gallons of fuel.

It’s also important to remember that engine and propeller combinations can vary, even among the same model of airplane. The company that markets the plane, for example, claims the range of a tank of gas can be over 1,000 miles, but that supposes running the tanks dry.

The picture of the crash scene in the Laramie newspaper (link above) doesn’t provide much of a clue other than that although there was enough fuel to start a grass fire, there apparently wasn’t enough to burn the plane.

But even that doesn’t prove fuel exhaustion. In an emergency landing, the pilot would typically shut off the fuel supply to the engine to prevent a post-crash fire.

  • kennedy

    With the wide range of possible fuel burn rates (6-10 gallons per hour) what is the recommended or common practice for calculating fuel needs? It seems to me that a flight plan with a possibility of running out of fuel is risky.

  • Bob Collins

    Keep in mind, we don’t know that’s what happened here.

    Fuel planning is part of what all pilots are *required* to do, including the 30 minute reserve (daytime). Calculating average fuel burn of a plane in various configurations is pretty easy the longer you fly.

    That said, most pilots who fly cross country I talk to say the bladder will fill before the fuel tank will empty.

  • kennedy

    The flight data in the link provided shows the last recorded position with an altitude of 12,100 feet and a speed of 135 knots. Laramie airport is 15 miles away at an altitude of 7200 feet. I don’t know the performance of the plane but an 8:1 glide is the minimum it would take to get there (not accounting for wind).

  • kennedy

    correction: 16:1 glide required

    8:1 is typical performance, so not enough to glide home from the last measured position.

    In comfort, I can’t calculate. Clearly even more difficult under pressure in the cockpit.

  • Bob Collins

    I’m still doing best-glide testing in the RV-7A but, generally, I’m seeing most RV-7 pilots reporting something in the neighborhood of 10:1. A lot of this also depends on the type of prop — fixed pitch vs. constant speed — one of which can be adjusted to reduce drag.

    I’ve been looking at the picture of the wreckage. There wasn’t much damage to the airframe — which is never good — and all landing gear collapse. Don’t see a lot of marks in the ground.

    The longer you can make a ‘crash’ last, the better your chances at survival. Very sad.

  • Mundelius

    I saw it happen and he stalled it on final about 100 feet AGL. Very sad for him. Was driving by and saw him in final crossed WY HWy 130 then right wing stalled and he went in. I was about 500 to 700 feet from the crash sight. Could not get to crash site due to a 10 foot airport fence.. Fire started on impact then a larger grass fire.