As an examiner giving a commercial pilot practical exam, I enjoy abundant discretion in the maneuvers I can ask the candidate to perform. For example, in testing the performance maneuvers, I can request a steep turn or a steep spiral as well as choosing between a chandelle or a lazy eight. No two exams need ever be the same, and it’s nice for me too because it keeps things interesting.
But eights on pylons must be part of every commercial exam. It’s one of the few maneuvers that’s also required on every flight instructor practical exam, and I confess the FAA’s fascination with eights on pylons has always puzzled me. Most pilots don’t seem to understand the basic ingredients and, honestly, I am rarely impressed when the maneuver is complete.
The Airplane Flying Handbook describes elementary eights—eights along a road, eights across a road, and eights around pylons—as a family of maneuvers based on the familiar turn around a point. In each case, the pilot makes roughly a figure eight pattern, guiding the aircraft around one pylon in a left bank and then around another in a right bank. In each case, it’s important to maintain a constant altitude and distance from the pylon during the banked turn.
Eights on pylons is a distant relative (think third cousin, twice removed) to the elementary eights. In this case, the pilot keeps a constant line of sight with the pylon and any winds means that both the altitude and distance from the pylon will necessarily change during the turn. It’s a fun math exercise to prove that, for a given ground speed in knots, squaring the groundspeed and dividing by 11.3 yields the appropriate altitude in feet above ground level called the pivotal altitude. Since the ground speed will naturally vary as the aircraft changes direction, the pilot needs to gain altitude when flying with a tailwind component and lose altitude when flying into a headwind. Deviating from this special pivotal altitude means that the pilot will not succeed in maintaining a fixed line of sight.
It’s a challenging maneuver and I vaguely remember performing eights on pylons on my own commercial checkride. At the time I hadn’t fully considered the maneuver, so passing the exam was more a testament of a forgiving examiner rather than any mad flying skills I fancied myself exhibiting. It seems that my own confusion wasn’t isolated, as during an internet search I found several flight instructors who don’t seem to understand the maneuver.
For those who may be eyeing an upgrade to a commercial or flight instructor certificate, I’ve assembled some practical advice in preparing for eights on pylons.
Understand the maneuver. An airplane isn’t an effective classroom unless it’s preceded by solid ground instruction. Make the most of the lesson with your instructor by consulting a reputable source first. The Airplane Flying Handbook has a good description of eights on pylons as well as common errors. William Kershner’s Advanced Pilot’s Flight Manual drives home the effect of wind during the maneuver and dispels any notion that the distance between the airplane and pylon remains constant. Kershner’s text features helpful drawings that show what the pilot will see during a successful version of eights on pylons.
Compute your pivotal altitude. No, I don’t mean getting your calculator out in the airplane and plugging in your ground speed while flying precariously close to the ground. At home, create a table that gives pivotal altitude for various groundspeed values. Once you estimate your ground speed, find the closest or interpolate between two and use that altitude—it’s good enough for government work (which passing a checkride in a sense is).
Start small. Moving directly from the elementary eights to eights on pylons is a big step because there is little time to concentrate on nailing the control of pivotal altitude before it’s time to find that second pylon. Start by cutting the maneuver in half for what I’ll call a turn on a pylon. Find an appropriate pylon with options for an emergency landing site should engine problems turn the airplane into a glider. Enter the turn on a pylon at the computed pivotal altitude and with a direct tailwind so that the pylon is approximately 1,500 feet off the wing tip. If the pylon appears to move ahead of the airplane, lower the nose to increase the airspeed. Pitch the nose up if the pylon seems to move behind.
Complete several circuits so that adjusting for pivotal altitude becomes second nature. Then vary the initial distance from the pylon and notice that it is still possible to maintain line of sight. The greater the distance from the pylon, the smaller the bank angle and the longer time you’ll spend in the turn. While a shallow bank angle might seem prudent the longer the maneuver takes, the harder it is. There is a happy medium where the bank angle stays reasonable, but the maneuver is flown efficiently.
Graduate to the full maneuver. With the ability to maintain a direct line of sight under your belt, choose a pair of distinctive pylons so that the axis between them is perpendicular to the wind. If you felt that, say, 1,200 feet is a comfortable distance, find pylons that are about 3,000 feet apart (roughly twice the radius plus a buffer for flying between the pylons). On the upwind side, fly parallel to that axis to get an estimate of your ground speed, find the pivotal altitude from the chart, and add that to the surrounding elevation (which is fairly constant because you wisely chose not to do this maneuver over hilly terrain). On the downwind side, fly parallel to the axis once more and enter on a 45-degree angle that cuts evenly between the two pylons. During the turn, use turn on a pylon technique to maintain a line of sight with the reference.
When rounding a pylon, look out for traffic and keep the other pylon in the scan to enter another 45-degree angle to the line between the pylons. It’s easy to roll out too soon after the first turn and end up flying over the second pylon, a common error that I witness on practical exams. It’s better to err on the side of rolling out too late if it means maintaining a responsible distance from the second pylon.
Finishing touches. Unless you have strong winds, the wind vector on your GPS is not a reliable way to determine wind direction. I’ve seen too many candidates align themselves downwind according to the GPS only to find that the “winds have shifted” once they enter the maneuver. Smoke emanating from a stack, the ripple of water on a local lake or even wind direction from a local AWOS is a much better indicator of surface winds than the GPS.
Know when to cancel the maneuver. The airmen certification standards dictate that other ground reference maneuvers should be flown between 600 and 1,000 feet agl and I delight when candidates use an altitude closer to the higher end. Since altitudes change during eights on pylons, it would be easy to calculate pivotal altitude to begin the maneuver and fail to realize that the altitude will become unsafe when flying into the headwind. For example, if a Cessna 172 flies the maneuver at 90 KTAS and the prevailing winds are 25 knots, the airplane will be less than 375 feet above the ground on the upwind portions—way too low! In this case, the pilot can choose to fly the maneuver at a higher power setting or simply wait for another day.
Finally, safety of flight is first and foremost. It’s easy to fixate on the pylon and fail to sufficiently scan for traffic. I’d personally rather see a candidate fly less-than-stellar eights on pylons because of looking out for traffic and terrain. Remember that the examiner can only write up the temporary certificate if she survives the flight.
Eights on pylons is an advanced maneuver and so satisfying to nail. With helpful ground resources and some practical advice, you won’t have to rely on a generous examiner in upgrading to a commercial certificate.