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Pilot's Handbook of Aeronautical Knowledge
Aeronautical Decision-Making
Hazard and Risk

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Likelihood of an Event
Likelihood is nothing more than taking a situation and
determining the probability of its occurrence. It is rated as
probable, occasional, remote, or improbable. For example, a
pilot is flying from point A to point B (50 miles) in marginal
visual flight rules (MVFR) conditions. The likelihood of
encountering potential instrument meteorological conditions
(IMC) is the first question the pilot needs to answer. The
experiences of other pilots coupled with the forecast, might
cause the pilot to assign "occasional" to determine the
probability of encountering IMC.

The following are guidelines for making assignments.
• Probable—an event will occur several times.
• Occasional—an event will probably occur
• Remote—an event is unlikely to occur, but is
• Improbable—an event is highly unlikely to occur.

Severity of an Event
The next element is the severity or consequence of a
pilot's action(s). It can relate to injury and/or damage. If
the individual in the example above is not an instrument
flight rules (IFR) pilot, what are the consequences of him
or her encountering inadvertent IMC conditions? In this
case, because the pilot is not IFR rated, the consequences
are catastrophic. The following are guidelines for this
• Catastrophic—results in fatalities, total loss
• Critical—severe injury, major damage
• Marginal—minor injury, minor damage
• Negligible—less than minor injury, less than minor
system damage

Simply connecting the two factors as shown in Figure 17-4
indicates the risk is high and the pilot must either not fly, or
fly only after finding ways to mitigate, eliminate, or control
the risk.

Although the matrix in Figure 17-4 provides a general
viewpoint of a generic situation, a more comprehensive
program can be made that is tailored to a pilot's flying
[Figure 17-5] This program includes a wide array of aviation
related activities specific to the pilot and assesses health,
fatigue, weather, capabilities, etc. The scores are added and
the overall score falls into various ranges, with the range
representative of actions that a pilot imposes upon himself
or herself.

Mitigating Risk
Risk assessment is only part of the equation. After determining
the level of risk, the pilot needs to mitigate the risk. For
example, the pilot flying from point A to point B (50 miles)
in MVFR conditions has several ways to reduce risk:
• Wait for the weather to improve to good visual flight
rules (VFR) conditions.
• Take a pilot who is certified as an IFR pilot.
• Delay the flight
• Cancel the flight
• Drive.

One of the best ways to single pilots can mitigate risk is to
use the IMSAFE checklist to determine physical and mental
readiness for flying:
1. Illness—Am I sick? Illness is an obvious pilot risk.
2. Medication—Am I taking any medicines that might
affect my judgment or make me drowsy?
3. Stress—Am I under psychological pressure from the
job? Do I have money, health, or family problems?
Stress causes concentration and performance
problems. While the regulations list medical conditions
that require grounding, stress is not among them.
The pilot should consider the effects of stress on
4. Alcohol—Have I been drinking within 8 hours?
Within 24 hours? As little as one ounce of liquor, one
bottle of beer, or four ounces of wine can impair flying
skills. Alcohol also renders a pilot more susceptible
to disorientation and hypoxia.
5. Fatigue—Am I tired and not adequately rested?
Fatigue continues to be one of the most insidious
hazards to flight safety, as it may not be apparent to
a pilot until serious errors are made.
6.Emotion – Am I emotionally upset?

The PAVE Checklist
Another way to mitigate risk is to perceive hazards. By
incorporating the PAVE checklist into preflight planning,
the pilot divides the risks of flight into four categories: Pilot in-
command (PIC), Aircraft, environment, and External
pressures (PAVE) which form part of a pilot's decision making