AVIATION SAFETY NEWSLETTER
Thought for the month..... Danger is relative, but poor planning magnifies it.
Plan-out Errors... A cockpit is a terrible place to try to make decisions. Even when
we are proficient in the aircraft we're flying, it takes a lot of brainpower to operate the systems and keep everything
pointed in the direction we want to go. One of the toughest decisions we have to make is whether to keep on going.
We usually have a bunch of external factors driving us toward our destination and it's really hard at times to
evaluate how changes that have occurred during the flight will affect the outcome.
When we plan a flight we normally provide some margins to help insulate ourselves and give us an opportunity to react to those changes. If we don't build-in those margins right from the start, then we have to make things up as we go along. When we do that, we open the door for an increase in the number of errors that can slip in. Some of the more obvious places we build in margins are weather, fuel, and performance.
Year after year pilots continue to prove that trying to fly VFR in IMC is fatal. When a pilot elects to continue into worsening weather, he is allowing his built-in margins to reduce to zero. Perhaps one of the reasons that happens is that the built-in margins were unsatisfactory. The warning bells that tell us that we're going to have to make a decision don't go off in time, or even at all. One of the first triggers that we should set to trap weather errors is whether the forecast and the actual conditions line-up with each other. If the forecast scattered is really broken, or the winds aloft are 20 instead of 10 and the temperatures are off by several degrees, its definitely time to get an update. Sometimes we won't do that because we're spring loaded to the GO position and we don't want to hear anything that will interfere with our plan. This is particularly true if the changes help us out, such as a 10-knot increase in our tailwind. But that might also mean that the generally benign winds we were expecting at our destination might be gusts to 30 and a 45º right crosswind when we get there. Differences between the forecast and the actual conditions could indicate errors trying to get at us through weather.
Many pilots fly with only a vague idea of how much fuel is going to be needed to complete the flight. This is particularly true for pilots who fly infrequently and rent aircraft. They're used to picking up the airplane with full tanks and that always seems to be enough to get down to Gaston's and back. If you just don't care to do the math and figure out what your actual fuel burn is, you'll need to adopt a really conservative margin. If the book says you have four hours of fuel, adopt three hours as being the maximum amount of fuel available. Visualize and treat the ¼ fuel remaining mark on the gauge as the empty mark. Even if we pick up an unexpected tail wind, it doesn't mean we have more fuel. More than one pilot has been tricked into believing that the increase in ground speed means they can over fly their intended fuel stop and continue on to the destination using the 60% to 70% power they were cruising at. If the wind falls off or changes direction before we get there, it could lead to a tight situation.
One of the fuel hazards associated with high-wing aircraft is that pilots don't seem to pay much attention to the individual fuel gauges because the fuel selector is on both. Fuel is gravity fed to the engine fuel pump from both tanks simultaneously - as long as both fuel lines are open. If one line is blocked, the four hours of fuel specified in the handbook just became two. Uneven fuel use should be a trigger we set to help catch errors trying to slip into the flight through the fuel system.
Each year numbers of pilots find themselves part of the landscape because ole trusty couldn't clear the trees at the end of the runway. The performance figures available in most AFMs or POHs need extra margins when trying to predict how an aircraft will fly in given conditions. The charts available to us were developed during testing when the airplane was new and being flown by a company test pilot. Fifteen or twenty years later, after having lived an exciting life, most aircraft aren't going to make those numbers. If you're flying from a grass runway that hasn't been trimmed lately, you just became the test pilot.
We normally think of takeoff as being the most critical time to get our performance calculations correct, but loss of control during landing is a major accident producer. One factor that affects landings is speed and we often land with too much of it. Operating handbooks usually list landing speeds for max gross weight. We don't normally land that heavy so if we use those figures, we're coming down the pipe too quickly. If we haven't planned our touchdown point accurately we may find ourselves floating down the runway, maybe to a point where we can't make a successful go-around. Conservative performance planning on takeoff and landing can help bar errors from ruining an otherwise fun flight. Proper planning can reduce the potential harm errors can cause. Failure to plan can magnify it.
MACTS - The Midwest Aviation Conference and Trade Show (MACTS) will be held at the Busch Student Center of Saint Louis University on January 7 & 8, 2006. Maps and information about the presentations can be found at www.macts.org. Flight instructors who have renewal dates through the end of April can attend the presentations for the sixteen hours of required training and renew their CFI certificate maintaining the same renewal date. Any flight instructor with a current certificate and a renewal date outside that range can renew early at the Conference, but will get a new renewal date of 31 January, 2008. There is a charge for flight instructors renewing their certificates at the Conference. For additional information go to: www.gslfia.com or call (314) 286-9905.
Register at http//faasafety.gov for E-mail notification of safety seminars in the St. Louis District.
Let's Not Meet By Accident
Operations Safety Program Manager
800-322-8876 ext 4835