The Recent Crash Of A Debonair In The Mountains Around Telluride......

My latest blog failed to discuss one of the worst small plane accidents that recently occurred. On February 16 at 1130 hours a 1960 Beech Debonair N400DJ took off from Telluride (KTEX) at around 1130 hours. Weather was light snow with visibility 1 mile, the average temp about 38F.

The reason I’m writing about this sad event is that there are some important factors to discuss, such as the negative effects of altitude on aircraft performance. There were no survivors in this crash, all three experienced aviators died at the scene.

The main effect of altitude is the decrease in air density as the altitude increases. The principle effect on the typical internal combustion engine is to decrease engine power output with increasing altitude. ( Reference from Airliners.net) Also the true airspeed of a stall increases at the rate of 2%/1000 feet. The indicated stall speed however remains unchanged. Very importantly, the rate of climb for a given airspeed decreases with altitude. This is what concerned me about this crash. The question being: could N400DJ climb fast enough to get around or over the surrounding terrain?

We may never know what brought these intrepid aviators down. I await the official NTSB report. I would have to wonder about engine performance and possible problems in that area.

In doing my reading, I also learned something about turboprops and jets and their problems with altitude. Apparently turboprops run into problems because of propeller efficiency and some jet types with their wing aerodynamics.

Before I sign off, I’ll tell you about a trip I made as a young and budding pilot in a Cessna 172 between Syracuse, NY (SYR) and Boston, MA (BOS). There were three fellow med students and I trying to go for a weekend break. Weather forecast so-so, VFR with clouds and minimal precip enroute. Temperatures were above freezing. Shortly after leaving SYR however, clouds started to appear. Scattered and low at first but as we kept going the cloud cover increased. As I was only VFR qualified, although I had some IFR training, I climbed above the clouds until I couldn’t get any higher. This was about 15,500 feet with no Oxygen aboard. We must have been in good shape as none of us passed out. Ouch! The airplane performance notably kept getting worse as we climbed higher. It felt light and a bit unstable. (Maybe some of that was due to light hypoxia on my part.) Finally when we got well past Albany (ALB) the clouds began to lessen. There were breaks that allowed us to see the ground, and as we passed Worcester, we could see Boston in the distance. All I can say is that we made it, and were damn lucky and awfully glad to put our feet on the ground when we landed.

So be aware of the limitations that may impact on your plane at higher altitudes. Check your flight manuals for performance data that applies.

Happy flying fellow pilots. May you fly high, fast and upright.

As February Draws To A Close And March Beckons.....

  

As February draws to a close and March beckons, I realize that it is time to publish another article for the blog. Nothing really has happened to stimulate a dramatic response from yours truly, so I’ll reflect on some rather mundane recent happenings as listed on the FAA accident reporting site.

How about the oft-mentioned gear-up landing? In this last week, there were five such incidents. They involved various types, including a sophisticated (and very expensive) Pilatus PC-12, two Pipers, a Cessna 172 a Mooney M20 and a Beech 35. That comprises quite a cross section of pilot skills (one wonders sometimes??).

The next series of accidents involved the landing or taxiing phases, some with landing gear involvement as well. For example: a Cessna170 landed and veered off the runway, two Cessna 172’s landed and struck snowbanks, one also damaging the landing gear; a Pa-46 (expensive) struck a snowbank that caused the nose wheel to collapse. Just three more. A Commander 114 slid off the runway after landing, another Bonanza had a “gear collapse” (usually a late activation of the gear handle) and finally a Cessna 421 clipped a truck with a wing tip while taxiing. These are all worth mentioning just to make the point that you’ve got to pay attention to what you are doing, especially during the landing phase of flight. Winter flying adds another layer of potential problems that must be anticipated and dealt with as they occur. An example follows.

Thinking about winter flying challenges reminds me of a winter about ten years ago here in Charlotte, NC. A week earlier I had flown in to Monroe airport (KEQY) in my Cessna 340 (N340JC), a pressurized, fully deiced twin. As Friday came and it was time to return to eastern North Carolina, the weather turned bad. There had been a cold front passage with some slushy snow and ice which for sure was going to be coating N340JC. The problem was that I couldn’t get into the hangar when I arrived as it was full, so had to park out in the open on the ramp. As a result the plane was going to be covered with a layer of frozen water/snow. Sure enough, when my future wife and I arrived at the FBO, the plane was coated from nose to tail with a white mix. We set about banging, scraping and cursing (non-productive). Finally after an hour or so the plane looked like it could fly. The control surfaces were clear, most of the ice/snow was off of the wings, tail with only a bit left on the top of the fuselage. I determined it safe to fly (if appropriate caution taken). As there was a very thin coating of ice on some of the wing I would have to use extra speed before lifting off. This would act as a safety factor to allow for a higher than normal stall speed. After a quick goodbye kiss I hopped in and started things going. As I taxied towards the departure end of the runway, I watched for snow collections or icy spots. None were seen, so far so good. The run-up went perfectly.  Before advancing the throttles I decided to add (empirically) 10 to 15 knots to normal take-off speed (usually 90 to 95 knots). This would be 100 to 105 knots. (Stall speed was 71 knots.)

As I advanced the throttles smoothly, everything seemed fine.  The engine acceleration was normal with the plane rapidly moving to 100 Knots. As I pulled back on the yoke, everything felt ok so I continued with the take-off. I noted that the thin layer of ice seen over some of the wing previously, rapidly disappeared. The remainder of the flight was uneventful, the weather excellent VFR.

The moral of the story: plan ahead particularly if things are atypical e.g. ice and snow. Have a plan and stick to it as long as it is working. In your plan include options for what to do if things don’t work out (plane feels mushy or sluggish). In the above case I would have terminated the take-off and taxied back to the ramp and pursued additional de-icing or considered renting a car and driven to my destination.

In summary: Don’t make dangerous unproven assumptions. Deal with the situation at hand as best you can. Always try and leave yourself an out.