Tuesday, September 13, 2011

Two Kinds Of Fatal Errors And How To Avoid Them

So, now it’s official, or at least formally proposed that some pilots are unable to fly when the autopilot quits. What are they talking about? Something that I have alluded to in previous articles. Pilots get more dependent on their digital devices and are then slow or unable to respond to basic flight data such as air speed, attitude etc. Face it with all those big screens showing you the way, who wants to bother checking primary data sources? But still, signs of a stall are not easy to miss. When the flight gets slow and mushy, you push the control column, not pull it back. We all learned that in the infancy of our flight training. And, when the needle of the airspeed indicator is in the yellow or red arc, watch out. You are already or soon will be stalling.

Now to be fair, I never flew the heavy stuff and had the opportunity to fly sexy simulators as the pros do, but even simulators can mimic a stall. In addition to improving flight training, the answer may lie in modifying training and installing yet another type of warning system for those unable to respond to unexpected situations.

Another different type of error may have been at least partly responsible in the recent crash of an airliner in Russia. According to news reports, the plane was slow to gain sufficient airspeed for liftoff, crashing near the end of the runway. There are multiple reasons for slow acceleration including: engine failure, slush or mud on the runway, low tire pressures etc. The failure to accelerate too slowly may be difficult for some pilots to perceive. There are techniques for recognizing and/or dealing with this. For example, I have heard of some aircrews that use a stopwatch to determine whether a critical speed is reached fast enough. This would apply when one has a co-pilot aboard. The technique I used was more basic. To have a point on the runway picked, for example, a building, that when the plane is abreast of it, the plane must be at a certain airspeed. Usually this would be lift-off speed. If too slow at this point, then the take off would be aborted, generally for most smaller airports, this would be about midfield.

In a past blog, I wrote about just such an event. My wife and I were at the Hendersonville airport several years ago. We were in the A-36. The day was warm in late autumn. The take off end, slightly uphill, was covered with loose stones. Since then the runway has been redone. This meant not shoving the throttle to full rpm too quickly to prevent stone damage to the prop. It also meant that the acceleration would be slower than usual. Before starting the take-off roll, I had decided that if we weren’t at takeoff speed by a certain set of buildings we would abort the takeoff. Well, sure enough, after a slow start, when reaching the decision point, airspeed was barely 60 knots. So we aborted. My wife at this point, never a happy flyer anyway, decided that I would make a test takeoff minus her. Oh, yes there were trees opposite the departure end of the runway. Well, the short of it was this. I taxied back for another try. This time however I used a short field technique. This meant one notch of flaps and about a 60-65 knot lift off speed. Then maintaining a slow airspeed just above stall until clear of all obstacles, then retracting the flaps and a return to normal airspeed. It worked perfectly, so I landed, picked up my wife and away we went, using the short field technique.

Again, the message is plan ahead. With regards to short fields, if not fast enough at a designated point, abort and go to plan B. When flying with the autopilot engaged, monitor what’s happening, and have a plan in case the autopilot quits.