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Are you ready to fly?


A review of preflight actions and risk assessments.

Checklists are used in – or should be used in – all facets of aviation. Incorporating them into preflight processes can help ensure thorough and standardized planning and preparation.
By David Ison
Professor, Graduate School Northcentral University

Aviation is full of checklists, standard procedures, and regulations that cover just about every aspect of flight. While these items help keep flight operations out of trouble, problems frequently begin to crop up before a flight takes off – and sometimes these obstacles decide to ride along.

A careful review of accidents shows that some of them had roots that can be traced back to the preflight planning phase.

Although it is obvious how critical preflight actions and planning are to flight safety, beyond regulations or company policies there is little by way of formal guidance or recommendations on how exactly to conduct all necessary preflight duties.

Much of the process ends up being at the discretion of the individual operator or pilots themselves.

Tools provided by FAA

Aviators are not left entirely in the dark about this critical part of flying. In addition to providing the bare minimum necessities via regulations, FAA has gone a step further with a few of what seem to be its favorite tools – mnemonics.

Reviewing these required and suggested items, along with resources from manufacturers, operators, and other organizations such as NBAA and AOPA, pilots can put together a standardized procedure of their own to ensure they do not miss any critical steps in the preflight process.

Starting with the regulatory side of things, of course, it depends on which set of rules apply to your flight operation. Regardless of whether you operate under Part 91, 135, or 121 regs, the barest outline of what should be done before taking to the skies can be found in FAR 91.103, Preflight Action.

Under this regulation, FAA states that pilots in command must “become familiar with all available information concerning that flight.” This leads one to think, “Well, of course. But what does that entail, specifically?” The rule goes on to state that, for all flights, you need to be aware of runway lengths and how your aircraft’s performance stacks up against these values.

When determining takeoff and landing distance, pilots must consider factors such as airport elevation and runway slope, aircraft gross weight, and wind and temperature. For IFR and flights away from the vicinity of an airport, the regulations require a review of weather reports and forecasts, fuel requirements, alternatives in case a flight does not go according to plan, and any known delays that may affect the operation.

In reality, of course, you will want to check all of these things whether or not you are IFR or leaving the traffic pattern, so I’ve always pretty much ignored that caveat. More factors come into play for IFR flights – for example, the issue of having an alternative plan if the flight cannot be completed as expected, eg, planning for an alternate airport.

This gets even more complicated for Part 135 and 121 operators, who have additional hoops to jump through. The “long story short” here is that a Plan B is often required and should always be considered. Again, the idea of having a Plan B – or even a Plan C – should be something that all pilots have in the back of their mind regardless of their type of operation or size of aircraft they fly.

A prime example of how important this is can be realized with the always-present “nearest airport” item as a readily available piece of information in onboard avionics.

PAVE checklist is a risk assessment tool outlined by FAA as a component of its overall recommendations concerning aeronautical decision making (ADM). While intended for use by individual pilots, it provides a foundation for hazard assessment strategies for all types of operation.

Regulations can be vague

Official guidance is somewhat vague. Some obvious things that should be considered are which specific weather reports and forecasts should be reviewed. As a flight instructor and stage check pilot, I remember students would often only check METARs and TAFs for the departure and destination airports, with little – if any – consideration for en-route conditions. Sadly, I have also seen this among professional pilots.

It also goes without saying that the weather check requirement refers to official aviation weather information, not reports and forecasts from the Weather Channel – although supplementing with such big-picture information never hurts.

The regulations outlined so far do not address adequately all necessary preflight considerations, but they are a starting point. Most notably, certain important elements are missing from the discussion, such as the pilot(s), aircraft, airport, and even passengers. This is where the mnemonics may enter to help keep us all on track when going through preflight machinations.


Perhaps PAVE (Pilot, Aircraft, enVironment, and External pressures) is the most familiar mnemonic. While still fairly generic, more guidance is provided on the recommended components of PAVE in various FAA publications.

Under Pilot, we can use another familiar mnemonic to help – I’M SAFE (Illness, Medications, Stress, Alcohol, Fatigue, and Eating). Pilots should always consider any of these components that may affect a flight negatively.

Further guidance from PAVE notes that currency and experience of the pilot are critical aspects as well. Some items to consider under Aircraft are performance, equipment, avionics, and fuel considerations.

For example, if the runway at the destination is somewhat short for the aircraft, what if there is a tailwind or some rain? Another example is the possibility of the weather radar not working, which could result in the flight skirting an area of convective activity.

Although the “V” for enVironment seems a bit hokey, let’s go with the fact that we should consider the weather closely throughout the flight, in addition to airport conditions and special hazards like icing and thunderstorms, while keeping in mind how the conditions stack up against the regulations and the capabilities of the P & A in PAVE.

External pressures can sometimes be a tricky part of flying. They include such pressures as get-home-itis and mission completion bias. Examples are the 12 o’clock meeting which the company CEO and investors must attend, while the closest alternate airport is too far away for them to make it in time.

Another example is the accident victim waiting for you to pick them up at a place where weather conditions are marginal at best. Having to make decisions to cancel or divert can be brutal at times, but nothing is worth your life or the lives of others.


Perhaps in response to the ambiguity within PAVE, FAA released a joint training standard with a personal and weather risk assessment guide that updated and augmented PAVE, resulting in the PAEDU methodology, where P still stands for Pilot, A is for Aircraft, E is used for Environment, D is for Duration (as in flight time), and U stands for Urgency (as in pressure to complete the flight).

The compelling aspect of the PAEDU model is that it enables you to calculate a total risk “value.” It’s essentially a score telling you how risky a flight appears to be, which is especially helpful when comparing the effect of different factors on the flight, as well as how the score on this flight compares to previous flights.

Rather than guessing risks, PAEDU provides a means to quantify them by rating each factor on a risk scale from 1 to 4. While this is somewhat subjective, it does put things in better perspective than “spitballing” it. You take your risk numbers for P, A, and E, add them together, and multiply them by the total of D and U.

Mathematically, this is (P+A+E) x (D+U). So, as long as the pilot is in good shape and experiencing little stress, P = 1. If the airplane is well equipped and functional, A = 1. If the weather is good, E = 1. If the flight duration is nowhere near the maximum endurance of plane or pilot, D = 1. If there is no urgency, then U = 1. The baseline score would come to 6. Via the equation, the calculation is: (1+1+1) x (1+1) = 3×2 = 6.

From there you can see how an urgency, like having to get to a wedding – a 4 on the risk scale – ramps up the risk value to 15 ([1+1+1] x [1+4] = 3×5 = 15). Add bad weather or other factors, and the number increases fast.

Each pilot has an individual matrix of attributes that make up their level of risk for a specific situation. Pilots must assess their perception of risk and their tolerance for such risk.

The go/no-go decision

Although this equation certainly shows how additional or changing factors can affect the risk of a flight, there is no official published scale offered, so final judgment is left up to the pilot to determine a tolerable level of risk.

Taking things a step further, FAA also provides a Flight Assessment Form with a finite scale to determine a “go” or “don’t go” decision.

In addition, operators have adopted tailored assessments that follow similar lines. These can be beneficial to decision-makers (pilots, dispatchers, etc) by establishing a red line between what is an acceptable risk and what is not, leaving little “wiggle room” where at times there may be a leaning toward taking unnecessary risks.

Assessment of pilot, aircraft, and environment is specific and exhaustive in the document FAA/Industry Training Standards: Personal and Weather Risk Assessment Guide.

For each value, the user selects the appropriate score for either a VFR or IFR flight – if the circumstance applies – and puts it into the “score” column. Positive scores can be interpreted as increases to risks, while negative values help cancel out such risks.

For example, if a pilot has fewer than 100 hours in type, they pick a +2 for VFR flights or a +3 for IFR flights, which would then be placed in the associated score box. An example of a negative score would be where the total fuel required for a flight with reserves is less than 60% of available fuel, giving a score of -2 on VFR flights or -3 for IFR flights.

It should be noted that the score values are not random. Instead, they are based on existing research into accidents and incidents, explicitly focusing on risk and how to mitigate it. Once all relevant scores are noted, they are tabulated to compare to the provided risk table.

Risk is delineated as minimal, low, medium, and high. Minimal risk flights are green-lighted as “go,” while high-risk flights are flat labeled “don’t go.” A low-risk assessment states that alternative actions should be considered, so that risk-reducing options can be weighed.

These include substituting a higher-time or more current pilot or copilot for one who is less experienced. Another solution could be to select an airport with a precision approach as the destination rather than one with only a circling approach (even if it is not convenient or close).

Medium-risk scenarios ask the user to consult an experienced CFI or, in the case of a professional pilot, other resources such as dispatchers or meteorologists.


The beneficial aspect of the flight assessment form is that it not only facilitates a hard “yes” or “no” to a flight – it also provides options for risk reduction, either by trying to remove high positive scores or by trying to get a few more negative scores to offset existing risks.

Thanks to FAA, industry, and researchers, many tools and references are available to assess thoroughly all necessary aspects of the preflight process. The key is to have a particular way of preparing meticulously for flights, and using it each time.

This is particularly helpful when things get hurried or when trying to get a flight off the ground in the middle of the night, outside the circadian rhythms of everyone involved. By following a guide or guides to preflight actions, pilots will be sure not to miss any essential items, thus minimizing risk and maximizing overall safety.

David Ison, PhD, has 35 years of experi­ence flying aircraft ranging from light singles to widebody jets. He is a professor in the graduate school at Northcentral University.