U.S. Department
of Transportation

Federal Aviation

St. Louis
Flight Standards District Office

10801 Pear Tree Lane
Suite 200
St. Ann, Missouri 63074


April 2000 




Thought for the month......All of us can exercise a certain degree of influence on someone, at some point, at some place.

Managing Aviation Errors....Errors in aviation can basically be broken down into five types - communication errors, decision errors, procedural errors, proficiency errors, and non-compliance or violations. At least one of these is present in every accident or incident. When we compare the proportion of errors and the consequences, or undesirable effects of those errors, some interesting relationships appear. For example, a study compiled over a 15 year period revealed that the highest percentage of aviation errors were non-compliance or violations. But, non-compliance errors also had the lowest proportion of consequences. The lowest percentage or errors were proficiency errors, but they had the highest proportion of consequences.

Non-compliance is a conscious failure to adhere to procedures or regulations so it makes sense that to violate a procedure or regulation, we must at least know what it is to begin with. We also probably have some concept of the possible consequences of our actions. If we elect to not comply with the requirement to make left-hand turns at a non-towered airport, we are probably aware that pilots who are flying by the rules will be entering traffic on the opposite side and we will be looking for them there. As a result, the risk that something bad will occur is reduced (high percentage - low consequence).

Because not following the rules rarely causes anything bad to happen, it's a pretty easy habit to get into. Eventually the rule is forgotten all together and the habit becomes the rule. The most frequent example of this is the use of a checklist. On a relatively uncomplicated aircraft, we quickly learn what should be checked and soon quit carrying a checklist around with us during the pre-flight. As we prove to ourselves that there are little or no consequences to pre-flighting a particular aircraft without a checklist it will eventually become a habit, our standard of operation.

Unfortunately, habits go with us when we fly other aircraft. Hey, a Bonanza is has all the same basic operating systems as a Cessna 152, two wings, three wheels and one motor. What's the big deal? Kick the tire, light the fire, press GO TO on the GPS.

A proficiency error is due to a lack of knowledge or skill. If we do not know how to intercept and track a bearing from a non-directional beacon, attempting to execute an NDB approach to an unfamiliar airport in the mountains in IMC conditions could have very serious consequences. The number of times we will put ourselves in that position is probably very low, mainly due to the fact that the first time will most likely be the last (low percentage - high consequence).

Improving proficiency has always been the goal of the FAA Safety Program. An airman with good proficiency is probably best equipped to survive non-compliance, poor decisions, bad procedures and screwed-up communications.

Decision errors occur with about the same frequency as proficiency errors, but the proportion of consequences is less than with proficiency errors. A decision error is defined as making a decision that unnecessarily increases risk. The decision error with the most notable consequences is the decision to continue VFR into IMC conditions. Decision errors are often combined with non-compliance, and the severity of their outcome is most directly affected by proficiency. A pilot may decide to perform aerobatics over the citizens of West County in his Extra 300. It's a bad decision and not in compliance with the rules, but because the pilot is proficient, nothing bad happens. Unfortunately, bad decisions that do not result in consequences can also become habit forming.

Procedural errors have the closest proportion with their consequences. A procedural error is when we follow a procedure incorrectly. If we input the wrong airport identifier into the GPS, the consequences are that we will go to the wrong place - garbage in, garbage out. The severity of the consequences will vary depending on whether we discover our error before the GPS leads us into a violation or worse. Procedural errors are often the result of human limitations or bad procedures to begin with. GPS's are not that user friendly. The same knob may have different functions depending on the mode or page being used. Many flight management systems have been programmed improperly, leading to disasters.

Communication errors complete the set. The relative frequency of communication errors in aviation isn't such a high percentage of the total, but the chances are pretty good that each time one occurs, something negative will result.

The current focus on runway incursions demonstrates that a combination of errors can produce consequences greater than their individual proportions. An incursion is always a procedural error, and usually combined with a communication error. Decision errors also affect all the error types because our decisions are influenced by our attitudes and personalities.

The results of such studies have been more than just an interesting set of statistics. They provide us with some pretty obvious options - we can either reduce the errors or reduce the consequences if we want to make flying safer. Traditionally we have targeted non-compliance. It's the easiest to discover and most frequently found. Unfortunately, even a significant reduction in non-compliance, would have only a minimal effect on the consequences. The real target remains proficiency, but because it has such a low proportion of errors to consequences, it's very difficult to make progress in that area. The two error types that can be most effectively addressed are procedural errors and decision-making errors.

Learning and teaching established procedures is the single most effective way of reducing errors and the consequences of those errors. Statistically, the ratio of consequences is less than the percentage of procedural errors so we have a little buffer to work with. Anything we can do to reduce procedural errors will have a multiplied effect on reducing the consequences. The most influential force in decision making is peer pressure. When we consistently use the correct procedures we set the standard for our peers. All of us can exercise a certain degree of influence on someone, at some point, at some place. Make it count.

Upcoming Events

Apr. 13
Creve Coeur Aviation
Creve Coeur Airport
Mid-Air Collision Avoidance
7pm to 9pm.

Jun. 1

Spirit of St Louis Airport
Thunder Aviation
Runway Incursions
Airport User Meeting
7pm to 9pm.

Jun. 5

Florissant Valley College Multi-purpose Room
GPS for VFR Operations
7pm to 9pm.


Safety Program Manager

1-800-322-8876 x 4835