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Aviation Risk Factors

Risk Factors

Every activity we undertake has a certain amount of risk involved. Some of us like bungee jumping or skydiving and have an inherently higher risk level than those sitting at home and reading a book or this website about flying.

Driving a car in every day traffic, despite the horrific accidents and numerous deaths, is an accepted basic need as we seem to think that the rewards are worth it. Everything is done to minimize the risk and reduce the chance of an injury even while some drivers are really trying to get someone else killed.

The same is done in aviation, rules and regulations are developed and might be seen as restricting but most rules came to be with safety in the back of the minds of the creators. General aviation is safer than ever but the risks can be high if the flight and its environment are not evaluated properly by the pilot.

Risk is cumulative and some say even multiplicative so that the effect of the individual risk becomes greater then the factor itself. Its like the whole is greater than the sum of its parts with all risk factors involved for the flight. Managing all resources to minimize the risk is the job of the pilot in command.

Evaluating flight factors

Every flight and its risk factors can be placed into four categories so that the pilot or crew can make any sense and be able to come to an accurately informed decision about the risk involved.

The aircraft

The type of airplane and the equipment on board are an important factor in the amount and level of risk involved in the proposed flight. Having a minimal IFR equipped C-172 or Piper PA-28 might lull the pilot into thinking that he is able to cope with the bad weather forecast for his flight. This is a false sense of security and it immediately raises the risk level.

Multi engine

The AOPA ASA Air Safety Foundation did some research into fatal accidents with small twin engined aircraft and the chance of having and engine failure doubled between Bonanza and Baron aircraft. Having two engines means basically that the chance for a failure is also doubled. But keep in mind that should one engine fail, the twin pilot can still fly to an alternate and the single engine pilot must land immediately.

It must be said that the twin pilot must be current and sharp on his/her skills flying with one failed engine to keep the aircraft under control, if not then the chances for a deadly accident are greater than in a single engine aircraft. Recurrent training is most important for the pilot.

Other factors contributing to a higher risk level can be summarized as follows:

  • Conventional versus nose gear configuration
  • High performance aircraft
  • Maintenance level
  • VFR only vs basic IFR vs full IFR equipped

Other equipment like: de-icing, radar and stormscope are not usually found on experimental homebuilt aircraft but they do raise risk in larger general aviation aircraft if the pilot does not receive proper training on these devices.

The pilot

As already mentioned in a previous article human factors are the most important variable with decisions impacting the safety of the flight, see also our chapter on human factors in aviation.

The FAA published the "I'm Safe" model for pilot self assessment and each letter represents a checklist item, click here for the complete pilot preflight checklist.

The environment

We can divide this into two parts: weather and day or night. Flying at night is inherently more risky than during the day and weather just ads tremendously to that risk level.

Weather limits

Meteorology is an important factor in aviation related accidents. When looking at the categorical outlook model, which is also used on the weather depiction chart by Jeppesen we can see several classifications:

Categorical Outlook
  Visibility Ceiling (ft)
VFR > 5 SM | 8047 m > 3000
MVFR 3 - 5 SM | 4828 - 8047 m 1000 - 3000
IFR 1 - 3 SM | 1609 - 4828 m 500 - 1000
LIFR 0,5 - 1 SM | 805 - 1609 m 200 - 500
VLIFR < 0,5 SM | 805 m < 200

Now check on your license if your IFR is valid and you are current in the logbook before setting off in IFR weather, even more so for VFR pilots when weather turns out to be marginal VFR either enroute or at your destination airport. The risk level is raised when you go on a cross country VFR flight in legal minimums: 1 SM and 500 ft AGL cloud bases. At that point you will enter the domain of the IFR pilot.

The situation

This is where you take all the factors together, make a list of all aircraft, pilot and environmental factors and combine them into a go-no-go decision. This is most of the time done on the day of the flight as weather can chance unpredictably.

A list of factors could contain items like: single engine airplane, IFR conditions, icing in clouds, short daylight hours, pressure of some sort, lack of recent flying/ landings, pilot fitness, fatigue, medical issues and so on.

Thus the situation is the sum totaling the other risk factors, with the pilot as the risk manager. You must constantly evaluate as factors chance during the flight and be mentally ready to make a diversion or land early if the situation asks for it. Remember that safety can never be sacrificed to obtain the goal of the flight.

Written by EAI.

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