How to fly a procedure turn
A reversal procedure turns you around at a fix and puts you on the inbound track, established for the approach. ICAO draws three of them: the 45/180 procedure turn, the 80/260 procedure turn, and the base turn, where the outbound track deliberately is not the reciprocal of the inbound one. All three start with a timed outbound leg of one to three minutes. This guide covers each shape, where the numbers come from, and how the wind and your speed change what you get.
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WHAT IS A REVERSAL PROCEDURE?
Sometimes you arrive at a fix pointing the wrong way for the approach. A reversal procedure turns you around in a known piece of sky and puts you on the inbound track, established and stable.
All of them start the same way. You cross the fix, track outbound on a published track, and time the leg. This trainer always times it, one to three minutes, which is what the ICAO figure shows and what works with an NDB as well as with a VOR. Then you reverse.
Your exercise starts half a minute before the fix, established on the track and tracking toward it, with the panel already set. That is 1 NM at 120 kt and 2 NM at 240, because half a minute is half a minute whatever you have set the speed to. So you fly the station passage first: watch the flag go from TO to FROM, and start the clock as it flips. Getting established is not the exercise, the reversal is.
The turn side is the manoeuvring side, the side a chart marks with a barbed arrow. Everything happens on that side of the track.
THE 45/180 PROCEDURE TURN
The one you will see most. At the end of the outbound leg, turn 45 degrees away from the track toward the manoeuvring side. Hold that heading for one minute, then turn 180 degrees the other way.
You roll out cutting the inbound track at 45 degrees, which is a comfortable angle to intercept. Turn onto the inbound track as the needle comes alive, and track back to the fix.
One minute on the 45 degree leg is the category A and B timing, which covers the speeds this trainer flies. Faster aircraft are given a little longer.
THE 80/260 PROCEDURE TURN
Same outbound leg, no straight bit in the middle. Turn 80 degrees away from the track, and as soon as you get there roll straight into a 260 degree turn the other way.
Those two numbers are not arbitrary. Eighty out and 260 back is a net 180 degrees, and the two turns are sized so you roll out on the inbound track rather than beside it. No intercept to judge, which is why some pilots prefer it. The price is that you are turning continuously for nearly a full minute.
THE BASE TURN
A base turn looks similar and is a different animal. The outbound track is not the reciprocal of the inbound track: it diverges by a few degrees. Then a single sweeping turn of a little more than 180 degrees brings you onto the inbound track.
How far it diverges is not a free choice, and there is a number for it: 36 divided by the outbound time in minutes.
- One minute outbound: 36 degrees.
- Two minutes: 18 degrees.
- Three minutes: 12 degrees.
It is a reciprocal because of where it comes from. A turn of about 180 degrees moves you sideways by two turn radii, so the outbound leg has to end that far off the inbound track for the turn to arrive on it. The longer the leg, the less divergence that takes.
Both the leg and the turn radius grow with speed, so the same base turn works over a range of speeds. Not all of them: above about 170 kt the turn is bank limited, the radius grows faster than the leg, and you sail through the track. Fly one at 120 kt and again at 250 with SHOW SOLUTION on, and you will see it.
TIMING, WIND AND CHECKING YOURSELF
Start the timer as you pass the fix, or abeam it if you can tell, whichever comes later. That is where the outbound leg begins, and it is why the exercise puts you a mile short of the station rather than already outbound: the station passage is part of the job.
Wind matters more here than in a holding, because you fly the reversal only once and there is no second lap to fix it. The same rules of thumb apply, and they are a suggestion rather than a law:
- Take the crosswind in knots, halve it, and use that as your wind correction angle on the inbound track.
- A headwind outbound means you cover less ground, so the reversal ends up closer to the fix. A tailwind pushes it further out.
The honest check is the map. Fly it, then use SHOW SOLUTION: the amber track is the procedure drawn to scale for the speed you flew, so your white trail should sit on it. Where it does not is where the timing or the wind correction was off.
Then hide it and fly the next one on the instruments alone.