Archive for July, 2008

Lancair Mishaps

Thursday, July 10th, 2008

The Lancair experimental aircraft: beautiful, fast and having what the FAA calls a “disproportionate” number of fatal accidents. There have been 7 fatals since February including the most recent, which occurred this week. Here are some preliminary FAA statistics running from October of last year:

Lancairs make up just over 3% of the amateur built ( AB) fleet yet have over 10% of the fatal AB accidents. Keep in mind, however, that they also tend to fly significantly more than the typical AB local flights. These are cross country machines.

Over half the Lancair accidents in this small sample were fatal while the rest of the AB fleet is just slightly above the overall GA fleet fatal accident ratio of 1 fatal mishap for every 5 accidents. Here’s what’s interesting – unlike the typical high performance aircraft that have fatal weather encounters, the Lancairs are generally in VFR conditions and involve loss of control – i.e a stall/spin.

A couple of observations: High performance aircraft may be squirrelly in stalls but not always. The certificated Columbia ( now Cessna) 350/400, which has ties to the Lancair early in its history, has a good stall/spin safety record. “Experimental” means that aircraft handling is left up to the designer and the extent of flight testing is entirely at the designer’s discretion. It may be very thorough or not. Factory built aircraft must meet specific construction and performance standards and are FAA tested for compliance. That’s one of the reasons for the cost differential.

There may also be variability in the building process. The designer suggests that it be built this way and the builder thinks he has a better idea or just isn’t adept at putting the machine together.

A few aerodynamic realities: Small wings and big engines make for very fast aircraft with high wing loadings and glide ratios not much better than the proverbial brick. If the engine stops for whatever reason, the crash dynamics are often not very good.

I believe that pilots should be able to build and fly their own aircraft. Extra training is one way to compensate, although not always successfully, with “hot” aircraft. There’s lots of history on that. Comparative statistics on any aircraft model’s safety are complex until you’ve accumulated enough accidents to say there’s a problem – the hindsight approach – and the denominator (exposure) factor is always squishy. Government crash testing, as done on automobiles, just doesn’t seem feasible for aircraft.

Your thoughts?

Summertime and the crashing is easy

Thursday, July 3rd, 2008

With apologies to Lyricist George Gershwin and singer Billie Holiday, the livin’ ain’t so easy as density altitude climbs. In the last few days we’ve had a couple of accidents that sure look like density altitude, although it’s too soon to say for sure.

Whenever I see high temperatures and high terrain I’m suspicious. When a high performance aircraft that is typically a strong performer at lower density altitudes is fully loaded, I’m almost ready to put money on it.

The two fatal accidents that appear to fit the DA profile both happened on June 29: In Santa Rosa, NM a Cessna 206 with 5 passengers was lost shortly after takeoff. One state over, at the 7,000 foot of a mountain close to North Las Vegas, NV, a Cherokee 6 also with five passengers crashed. We’ll learn more as the investigation goes forward but if this is the case, to lose 10 people in one day because the pilots forgot that sea level performance doesn’t exist in the summertime is sad, expensive, and really unacceptable.

My experience with hot and high makes me conservative on who and how much to carry. Trip legs are frequently shorter as fuel load is lightened and I really study the route carefully so as to be at altitude before getting to the high terrain, if that’s possible.

Leadville, COSome years ago when taking a mountain flying course, while pausing at Leadville, CO to get the certificate for being at the highest airport in the U.S. , I watched a fully loaded Cessna 172 almost do the deed. The airport picture makes it look deceptively easy. The Skyhawk is not exactly a ball of fire with all seats full at sea level. With a runway of 6,400 feet, that’s less than the field elevation of 9,927 feet msl the Cessna pilot clearly did not understand what he was up against. With four people on board the Cessna rolled and rolled and rolled. It sagged off the ground, caught its breath in ground effect and then sagged some more into the the cool thin morning air. That coolness was the only thing that saved them because by early afternoon there would have been no climb at all – only forward and down.

If you haven’t done much high terrain flying recently take a look at ASF’s mountain flying course.

As we did in talking about near fuel accidents, share your experiences that you or a “friend” had in learning about density altitude beyond the academic view. Is there a way we could be teaching this more convincingly?