Re-Thinking Risk Assessment

Robert Chapin
2016-12-24T12:51:16+00:00

Assessing Risk, image from Risk Management HandbookThe best tool available for pilots to quantify overall flight risk is the form found in the FAA’s Personal and Weather Risk Assessment Guide.  However, that form is more than 10 years old and needs many improvements.  It is based on the “PAVE” method or checklist, and enables a pilot to assign a predetermined point value to each area of risk.  This helps to minimize subjectivity and encourages detailed preflight planning.  Using this process in connection with Aeronautical Decision Making is a great idea, but I want to illustrate several ways to make it more complete and hopefully more accurate.

PDF Icon Flight Assessment Form Download (29 KB)

Unidentified Risk

One of the six types of risk defined in the Risk Management Handbook is unidentified risk.  This concept is relevant to the Flight Assessment Form in two important ways.  First, by definition, “some risk is never known,” and one cannot quantify what one does not know.  Second, the Flight Assessment Form simply fails to identify many risks by omission.  There are also certain line items that I feel are too coarse in terms of assigning points above or below a certain threshold while ignoring more severe or inverse conditions.

Fuel Calculations

The two line items used to assess fuel management risks are inadequate in at least one quantifiable aspect.  The first line item reduces the risk score when the pilot calculates and confirms the minimum fuel quantity required by applicable flight rules.  The second line item further reduces the risk score when the required minimum fuel is less than 60% of the usable fuel quantity.  Scoring here seems to be based on an assumption that common fuel management techniques never increase the overall risk of flying.  However, pilots also commonly assume the risk of flying aircraft that have notoriously unreliable fuel gauges.

If on a percentage basis the minimum fuel calculation is in error due to a change in aircraft performance, a change in wind conditions, or due to incorrect preflight calculations, then it is possible to identify the risk of flying with a usable fuel quantity less than the minimum plus the percentage margin of error.  This is particularly relevant to any aircraft lacking fuel flow or totalizer instrumentation that could be used to verify the calculations in flight.  For example, I assume that the acceptable risk of a fuel flow error is 25%, and the required minimum fuel quantity is 100 gallons.  If the usable fuel quantity is less than 125 gallons, then the identified risk is not zero.  Consider that, for a flight longer than 1.5 hours, a fuel reserve of 0.5 hours would be smaller than the margin of error because 0.5 hours is only 25% of the required 2.0 hours endurance.  I describe this risk as follows:

< 25% extra fuel and no fuel flow instrumentation (+2 risk)

I also want to end the risk reduction based on a preflight calculation for minimum fuel only.  The reduction should only apply to airplanes that do have a fuel flow instrument:

Fuel & reserves calculated & fuel flow monitored (-1 risk)

Low Visibility

The visibility factors on the Flight Assessment Form never made sense to me because they occupy multiple line items and assign zero risk to IFR flights with more than one mile visibility.  Clearly, this is an unidentified risk.  Even worse, IMC visibility only increases the VFR risk score by three points.  How could that be right?  I suggest a much more aggressive risk value for any visibility less than ten miles:

Visibility – Each mile less than 10 SM (+3 risk VFR; +0.5 risk IFR)

Flying at Night

Night flying is mentioned in the PAVE checklist, but somehow omitted in the Flight Assessment Form.  To its credit, the AOPA Flight Risk Evaluator has a night flying question on the first section of its forms.  I feel the primary risk of flying at night is the limited positional awareness potentially caused by near-instrument conditions.  I decided to add a single line item without getting too complicated:

Flying at night (+1 risk)

Controlled Flight Into Terrain

The FAA included an entire CFIT Checklist at the end of the Risk Management Handbook, but it is too large and complicated to incorporate into the overall assessment.  I think the most significant CFIT risk that needs to be included is a reminder to check terrain elevation along the planned route.  Flight students are instructed on how to do this, but when training in non-mountainous areas this practice is usually not reinforced during flight plan reviews.  I summarized this concern in one line item:

MEF or OROCA above cruise level minus 2000 ft (+1 risk)

Extreme Temperatures

Surface temperatures influence many risk factors that should be quantified in some way.  Aircraft performance, climate control, ramp safety, hydration, and emergency preparedness are always changed by a temperature outside of the usual and comfortable operating range.  This is true whether operating near the surface for prolonged periods of time, or when climbing into cold air, or descending into hot air.  I used my personal comfort range and the type of equipment to arrive at this new line item:

Surface temp less than -5° C or more than 35° C (+1 risk)

Unacceptable Risk

While it might be helpful in some situations to quantify the risk of flying into known icing conditions, visibility less than one mile, or ceilings less than 500 AGL, in many situations these are considered unacceptable risks.  These should be defined by personal limitations or standard operating procedures.  The Flight Assessment Form needs to be modified with a few extra blank lines, or customized with a list of disqualifying factors.

Acceptable Risk

Some of the existing line items on the Flight Assessment Form need to be clarified or tweaked for accuracy.  Here is a list of the additional changes I’ve made.

Supplemental Oxygen

The two supplemental oxygen line items, one for day and one for night, seem redundant and might not apply to all pilots.  I have never perceived an increased risk flying the same cruise altitudes at night as during the day.  While I don’t doubt that there could be some very small influence on night vision and other factors, I just don’t agree that flying 6,500 ft at night would be more risky than flying 4,500 ft.  I removed the extra line item on my version of the form and simplified the wording.

Above 10,000′ PA with no supplemental oxygen (+2 risk)

Fuel Reserves

The description of fuel reserves on the Flight Assessment Form is wordy, confusing, and has annoying typos.  This is easier to understand:

Required fuel and reserves plus 67% extra (-2 risk VFR; -3 risk IFR)

Runway Length

It is too wordy and confusing to try to ask a pilot how much runway they will use.  I simplified the description to focus on the length of the runway.

Runway length less than 200% of requirement (+2 risk)

Low Ceilings

Should conditions such as OVC029 and OVC011 receive identical risk scores?  I think not!  I usually want my students to have a ceiling much higher than 3,000′ AGL anyway.  This needs to be revised to quantify the risk in 100 ft increments.  That can be done in a single line item.

Ceilings – Each 100′ less than 4,000′ AGL (+1 risk VFR; +0.1 risk IFR)

Radar Environment

The phrase “radar environment at destination” is rather nebulous to new pilots.  I revised this line item to remind my students that they can look in the A/FD for the ® symbol.

Radar environment at destination (circle-R symbol) (-1 risk)

IFR Flight Plan

An error on the Flight Assessment Form shows the IFR risk reduction in the VFR column.  I simplified this line item.

VFR flight following or IFR flight plan in VMC (-1 risk)

1 Feb 2015

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Aeronautical Knowledge

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