A lack of knowledge is a dangerous thing

by Dale Nielsen

At this time of year, most of us fly less often than we do during the spring, summer and fall. Our flying skills may get a little bit rusty. We may also get a little rusty in our knowledge of aircraft procedures, systems and emergencies. Flying skills are as much mental as physical. A review of the aircraft manuals before the next flight may be warranted.

The pilot of a Cessna 305 reported the aircraft engine quit as he was making a left turn after takeoff, resulting in a forced landing into some trees. He did not use carb heat before takeoff to ensure the engine was clear of carb ice, despite weather conditions conducive to carb icing. He believed the type of pressurized carburetor installed in his aircraft was immune to carb icing.

The pilot of a Piper PA 32R was flying IFR when he noticed a gradual loss of electrical power. He requested a diversion to a nearby airport for landing. Enroute to the diversion airport, all electrical power was lost. On arrival at the diversion airport, he circled overhead until he received a green light from the airport control tower. On final approach for landing, the green light from the tower changed to red. The pilot went around for a second approach, from which he landed with the landing gear up. When asked why he did not lower the landing gear with the emergency landing gear system, the pilot said he thought he felt landing gear drag when he used the normal landing gear lever (electrical activation of the gear system).

Shortly after takeoff, a Beaver RX550 ultralight was seen to pitch slightly up, roll rapidly to the right, and descend in a steep nose down attitude into the ground. The pilot died and the passenger was critically injured. Examination of the Rotax 503 two-stroke engine revealed sudden stoppage due to "four point piston stoppage." According to the engine manufacturer, such a seizure is a severe piston sidewall scuffing phenomenon, resulting from inadequate engine warm-up.

The pilot of a Piper PA 25-235 Pawnee flew a trip of one hour and 12 minutes, after which he added 27.5 U.S. gallons of fuel to top up his tanks. He then attempted to fly the aircraft on a planned two hour ferry flight to home base, at 2,350 rpm and with the mixture full rich. One hour and 42 minutes later, the aircraft ran out of gas. The pilot survived a forced approach to a field.

The Pawnee pilot stated that he normally used the aircraft owner’s performance data, which indicated a fuel burn of 15 U.S. gallons per hour at 2,350 rpm, and a tank capacity of 35 U.S. gallons. The fuel used during the previous trip showed the actual fuel burn with the mixture at full rich was actually 23 U.S. gallons.

The pilot of a Grumman American AA5B Tiger attempted to land on a 2,000 ft bumpy, wet, up slope grass runway, in a 30 degree crosswind at 15 kts gusting to 20 kts. He approached at 70 kts with the flaps retracted. He touched down one third of the way down the runway, pumped the brakes to try to stop, overran the end of the runway, proceeded down an embankment, and struck a tree. The Pilot’s Operating Handbook indicates the approach should have been flown at 63 kts with the flaps full down. The landing roll on a dry grass runway should be 1,046 ft with maximum braking.

The Cessna 305 pilot did not know his carburation system. Pressurized carburetors can get carb icing. Many pilots check carb heat operation during the run-up by checking for the drop in rpm when the carb heat lever is pulled, and they check for the rise in rpm when the carb heat lever is return to the cold position. Too few of us leave the carb heat out long enough to see if the rpm will rise on its own after the initial drop. Carb ice can, and does, happen on the ground during taxi for takeoff. If carb ice is detected on the run-up, or if the weather conditions are conducive to carb ice, it is a good idea to re-select carb heat once more just before takeoff, to confirm the carb is free of ice.

The PA 32R pilot did not know his landing gear system. If he wasn’t absolutely sure the landing gear was down, he should have used the emergency gear system. The sudden change of the signal light from the tower, from green to red, should also have warned the pilot that something was amiss.

The Beaver RX550 pilot did not know the warm-up requirements of the Rotax 503 engine.

The Pawnee pilot did not attempt to determine the actual fuel burn of his aircraft.

He also did not seem to know that the employer’s fuel burn figures were based on a properly leaned mixture, or that the mixture should be leaned when on a ferry flight.

The Transportation Safety Board determined the Tiger pilot had sufficient runway to carry out a safe landing if he had flown the approach according to the manufacturer’s recommendations, and had used proper braking technique. Touching down near the start of the runway would also have helped.

Attempting this landing on the surface described, and under the wind conditions at the time, may have been possible – but it was not wise. Slippery, wet grass may easily double the landing roll. Bumpy surface conditions also reduce braking effectiveness. An up slope will help, but how much in this case, we don’t know. A gusty crosswind certainly increases the difficulty of an approach, and may make it tough to land on the selected touch down point.

Each of the pilots in the accidents described above did not know something about their aircraft, and it cost them. A periodic review of the aircraft operating procedures, systems and emergency procedures is a good investment of time. Over time, aircraft and engines may not perform exactly as they did when new. Take this into consideration when reviewing aircraft performance figures.

Mental preparation for a flight is the most important part of pre-flight planning.

There is safety in knowledge.