Preflight Action - FAR 91.103

Preflight Action - FAR 91.103

By Jordan Bullock CFI, FO B737

The first topic usually discussed in flight school is the daunting preflight. Most pilots see it as a barrier to them and the sky. Something that consumes a chunk of their precious time. Usually, a preflight is physical in nature, checking the quality of the aircraft before you get in the air. This usually includes a physical walk around of the aircraft, a sampling of the fuel to ensure no contaminants are found, checking that the lights work, checking the oil quantity and a number of other things on the actual aircraft. This walk around is what a lot of pilots consider as the only facet of the preflight.  While the integrity of the aircraft is extremely vital to the flight, a vast majority of pilots overlook other tasks that should be a part of a good preflight.

Thankfully, the FAR AIM points us in the right direction. In §91.103, it states: 

Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—

(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.


As this shows, the preflight process goes well beyond simply sumping fuel and kicking the tires. So let's break it down and take a look at what you should be doing to properly preflight before you take to the air. 

IFR Flight or Flight Not in The Vicinity of an Airport

The first part of this regulation is for instrument flights or flights being conducted away from airports. There’s a multitude of things mentioned so let's discuss how each one is important to the safety of flight. 

Weather reports and forecasts are the first task mentioned. Obviously weather is a big deal for aviators, especially during an IFR flight. Knowing what kind of weather to expect not only at your destination, but enroute is vital for every flight. If hazardous weather exists or is to be expected, it’s best not to conduct the flight. 

Mentioned second is fuel requirements. Depending on whether you’re flying on an instrument flight plan, or just going VFR and burning holes in the sky, a different fuel requirement must be met. Abiding by the legally mandated fuel requirement will ensure you don’t run out of gas miles up in the air. 

Next, the reg mentions alternates. Having a planned alternate, even when not required, just might save your life one day. A lot of times the weather can change instantly and you can find yourself without a plan b. By planning ahead of time and having an alternate airport in mind, you ensure that you’re fully prepared. Be sure to choose an alternate that suits your needs. Things to look at when choosing an alternate are: runway lengths, weather, services and distance from your planned arrival airport. 

Finally, the reg mentions ATC delays. Often busy airports, or airspaces, will issue ATC delays. This allows a pilot to plan ahead for any delays that might occur. Many times, it's metering the number of aircraft going into a specific area. This could cause you to wind up holding in the air and potentially burning precious fuel for which you might not have planned. 

Most of the tasks mentioned in this first part are time sensitive. The point of the FAA throwing these preflight tasks into their regulation book is to emphasize how important planning is.

Runway Lengths and Conditions

The second part of this regulation has to do specifically with performance. It states, “...other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.”. This portion of the regulation is essentially discussing takeoff and landing performance along with airport and runway information. Let's break each one down and look at it. 

First up is aircraft performance with airport elevation and runway slope. Airport elevation is extremely important and oftentimes not taken into account by pilots. The higher the elevation of the airport, the more runway that will be required for you to takeoff. The slope of a runway has a similar effect for taking off, as going uphill will require more distance to reach your rotation speed. The slope of the runway can be found in the FAA’s Chart Supplement. 

Next aircraft gross weight is listed. Obviously, the weight of the aircraft has instant implications on your landing roll. Assuming you’re inside weight limitations, the heavier you are the more runway you will need to takeoff or land. For larger jet aircraft, the gross weight of the aircraft is even more important as certain runways are limited to strict weight restrictions. 

Last but not least, the regulation mentions wind and temperature. In the Pilots Operating Handbook of your aircraft, varying charts and graphs are given for takeoff and landing performance. Giving you a distance in feet that will be required, which allows you to ensure the runway you plan to operate on is long enough for takeoff and landing. The temperature and winds affect these performance numbers, so ensure you are using the right graph for the present weather conditions. 

Conclusion

Many pilots assume a preflight is simply a physical walk-around of an aircraft. The point of §91.103 is to ensure that every pilot is taking into account the tasks that go beyond the mechanical side of flying. Checking the weather, ensuring your performance and all the other tasks mentioned is just as important as the operation of the aircraft. Remember, a pilots job begins and ends on the ground!

By Jordan Bullock CFI, FO B737

Northstar Aviation References brings you the Pre-Tabbed ASA FAR/AIMDIY tabs for your FAR/AIM and other pilot resources such as prepware so that you can more easily study the regulations that form the foundation of your flying career or hobby. Have any questions? Check out our FAQs page or contact us. Check out other blog posts here.