5.D : Taxiing

The student should develop knowledge of the elements related to taxiing an airplane as required in the ACS/PTS.

References : Airplane Flying Handbook (FAA-H-8083-3C, page(s) 2-14,10-6)

To taxi the airplane from point A to point B on the airport surface a pilot must know how to interpret the signs and markings used on the airport grounds. The most ubiquitous taxiway marking is the continuous yellow centerline stripe. Stay centered on the stripe to stay safe. At certain airports there are also taxiway edge markings. A continuous yellow line means that the shoulder is not intended for use by aircraft, and a dashed line means an aircraft may use at least a portion of that pavement.

Holding short lines denote a location that the aircraft must not cross until it is cleared to do so. These lines are four yellow lines stacked together, two solid and two dashed. When approaching the hold short lines from the dashed side the aircraft may cross without clearance, but when approaching from the solid side the aircraft must have a clearance before progressing.

Along with the surface markings signs help direct the pilot to the desired location on the airport surface. The following image show a number of the common signs found on the airport surface. This includes runway designation signs, ILS critical area indications, taxiway locations, pointers indicating taxiway directions, taxiway ending signs, as well as others.

Once the pilot knows how to find their way around the airport, they must know how to control the aircraft while taxiing on the airport surface. Steering is generally accomplished with the rudder pedals and brakes (there are some exceptions, but this is the most common arrangement for small aircraft).

To turn apply rudder in the direction of the desired turn, and use power/brake to control the taxi speed. It can be the case that brakes are needed to facilitate a turn, and this is done by adding brake on the "inside" of the turn. Rudder is held until just short of the point where the turn is to stop, then pressure is released to maintain the taxiway centerline.

Brakes are used to both assist in turns, moderate the taxi speed of the aircraft, and stop the aircraft. Do not ride the brakes as this can unnecessarily wear and heat the brakes, and in extreme cases this could heat them enough to start a brake fire. Moderate taxi speed with throttle as much as possible. Speed is controlled first with throttle, and second with brake. It should be noted that you may need to use some extra power to start the aircraft moving, but that power should be pulled back to a more moderate level once the aircraft breaks loose from the parking spot.

The centerline should be maintained during taxiing, and the student should work with the instructor to determine the sight picture that results in a position on the centerline. Adjust the sight picture as needed for the individual pilot and aircraft.

At an airport with a tower, permission must be obtained before taxiing the aircraft into a movement area when the tower is in operation. Together, runways and taxiways are known as the movement areas of the airfield. All other areas (ramp, etc.) are considered non-movement areas. A clearance also must be obtained prior to crossing any runway. ATC will issue an explicit clearance for each runway crossing. Any runway means literally any runway, whether active, inactive, open, closed, etc.

When assigning taxi instructions ATC will specify :

Always read back the taxi instructions to the controller. Before taxiing ensure that they make sense, and that every step is understood. If there is any doubt have the instructions clarified, or request a progressive taxi. Always have an airport diagram on hand to help identify the route issued.

At the start of taxiing there are a few quick checks that should be performed. As the aircraft starts to move out of the parking spot perform a quick check of the brakes to insure they are functioning properly. If not, retard the power and shut down the aircraft immediately.

Verify instruments by confirming that the attitude indicator shows no more than about 5° of either pitch or bank. The turn and slip indicator should indicate the movement in the direction of turns, and that the inclinometer is full of fluid. The magnetic compass and heading indicator should be moving toward known headings and that the magnetic compass shows no cracks, fluid leaks, or bubbles.

During taxi operations the wind should be factored into the positioning of the aircraft controls. Taxiing downwind will generally take a little less power after the ground roll has started. To avoid overheating the brakes keep engine power at a minimum and only apply them occasionally.

Taxiing with a quartering headwind ailerons should be turned into the headwind and the elevator is held neutral. This helps avoid having the wind lift the upwind wing. The upwind aileron is UP reducing the effect of the lifting action, and the downwind aileron will be DOWN adding a small amount of lift/drag on that wing to also help keep the upwind wing down.

Taxiing with a quartering tailwind requires different controls positions. The way many remember positioning is that the ailerons are positioned to "dive with the wind" and the elevator is positioned DOWN. These corrections help minimize weathervaning and provide easier steering.

It is critical to maintain situational awareness of the environment and the location and movement of other aircraft and vehicles. Visually scan the area constantly looking for hazards, and the pilot should spend a minimum amount of time with their "head in the cockpit". Any checklists should be completed only when the aircraft is not in motion.

While taxiing also monitor the appropriate frequency, and use transmissions from other aircraft or ATC to help maintain situational awareness. During taxiing apply all the normal aircraft right-of-way rules, and don’t become a hazard by inattention.

Taxi slowly, and when yellow taxiway stripes are provided they should be observed. Slow before turns, as high speed turns put excessive load on the gear and can risk an upset or ground loop.

When taxiing, maintain a sterile cockpit to avoid distractions. There should be no checklists being run, conversations, phone calls, texting, or other distractions which would detract from a safe taxi operation.

Always have a taxi diagram if available. Read back all taxi instructions, hold instructions, and do so using proper phraseology. Review NOTAMs for the airport prior to taxi (looking for taxiway closures, construction, etc.) and be familiar with airport markings and signs. If in doubt, request a progressive taxi.

While taxiing use proper position and taxi lights, and when landing clear the runway in a timely manner. At night there often is an aircraft light which is considered most useful for taxiing, and this is often referred to as the "taxi light". In addition, it is often considered a good practice to operate the aircraft anti-collision light while taxiing, just to increase visibility.

In the event of a radio malfunction it may be necessary to resort to the use of light gun signals. If possible prior agreement with the tower for use of light gun signals should be made, and there must be a clear understanding on the part of the pilot as to the meaning of the various signals.

Requirements for safe taxiing include positive control of the aircraft, the ability to recognize potential hazards in time to avoid them, and the ability to stop or turn where and when desired without undue reliance on the brakes. Also, be aware of other traffic and its movement, write down and read back all clearances, and maintain the proper crosswind correction.

To determine that the applicant: