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Rectangular Course

A rectangle flown at a constant distance around a field, low enough that the wind's effect on your track is impossible to ignore. It is the traffic pattern with the runway taken away and the drift left in.

Ground Reference Maneuvers — FI.X.A

Why you fly it

The stated objective is the one an examiner works from — that you understand ground reference maneuvers, can apply that understanding, manage the risks of maneuvering at low altitude, and fly to standards. What it actually builds in you is narrower and more useful: the habit of flying by what you see outside, and the reflex of fixing a ground track with bank rather than rudder.

That reflex is the reason the maneuver exists. The airplane flies through the air, but your track is over the ground, and the two only agree in still air. A pilot who tries to stretch a ground track with rudder alone ends up skidding — and a skidding turn at pattern altitude is the setup behind the base-to-final stall, with no altitude left to trade for a recovery. The rectangular course is where you learn to see drift early, while the correction is still small.

The shape is not arbitrary either. Four legs held at a fixed distance from a boundary, with a corner between each pair, is the geometry of every pattern you will ever enter. Out here nobody has painted a runway down the middle of it, so there is nothing to aim at, and no way to mistake pointing at the field for tracking beside it.

Setting it up

Choose a field with square, well-defined boundaries — section lines, a fenced pasture, a block of orchard — with open country around it. The open country is not just a convenience. Over a congested area, 14 CFR 91.119(b) requires 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet, which puts this maneuver out of reach entirely. Over other than congested areas, 91.119(c) requires 500 feet above the surface — except over open water or sparsely populated areas, where there is no floor above the surface at all and the requirement is instead that you come no closer than 500 feet to any person, vessel, vehicle, or structure. And 91.119(a) applies everywhere: an altitude from which you could make an emergency landing without undue hazard to persons or property on the surface.

So the 600 to 1,000 feet AGL these maneuvers are flown at belongs over sparse country and nowhere near a town. That band is a compromise: high enough to give you a few seconds if the engine quits, low enough that drift is obvious out the window.

Read the wind before you get there — smoke, dust, crop rows lying over, ripples moving across water, the drift you noticed flying out. Friction slows and backs the wind near the surface, so the wind at 800 feet is not the wind the tower gave you on the ground.

Then run a pre-maneuver flow. CHAPS is one common version of it. It is a school mnemonic rather than FAA material — you will not find it in the Airplane Flying Handbook, the PHAK or the ACS — but it covers the ground those documents ask you to cover before you maneuver low.

• C — clearing turns. Two 90s or one 180, with your eyes outside. Traffic displays help; they are not the scan.
• H — heading. Note the entry heading, so you know where you started and where the wind was.
• A — altitude. Be in the band and level before the first leg, not fixing it on the way round.
• P — proper configuration. Set the power your POH gives for maneuvering, along with anything else that airplane asks for — mixture, carburetor heat, and a propeller control or fuel pump if it has them — and then leave it alone.
• S — safe place to land. Pick the field you would use and brief the engine failure out loud.

Enter on the downwind leg, parallel to a boundary, at a distance you can hold — close enough that drift is visible, far enough out that no turn needs more than a medium bank. That distance becomes the distance for all four sides. The rectangle you fly is the field offset outward, not the field itself.

The four legs

Textbook diagrams, the Airplane Flying Handbook's included, draw the tidy case: the wind square to the course, so two legs are pure crosswind and two are pure head or tail. Real air rarely lines up that way. Lay the course out against whatever the wind is actually doing and every leg needs some correction, in different amounts — which is the case worth practicing.

In the clean case your heading is your track on the downwind and upwind legs, and the wings stay level. On the two crosswind legs they cannot be: you hold a heading angled into the wind and let the airplane travel sideways down the boundary, which is the whole point of the exercise. It feels wrong the first few times, because the nose is not pointing where the airplane is going. When the wind sits at an angle to the field instead, that same crab appears on all four legs, larger on some than others, and nothing else about the maneuver changes.

Groundspeed changes on every leg — fastest downwind, slowest upwind — while your indicated airspeed stays very nearly constant, because the wind is not something the airplane feels. Leave the power where you set it, hold altitude with pitch, and trim off the pressure so the airplane keeps what you gave it while you are looking outside. Pitch and power are a pair, though, not rivals: if altitude will not hold at the power you chose, adjust the power rather than fight it with pitch alone.

The four turns

Each corner is flown differently, in two ways at once. The bank differs at all four, because the groundspeed differs at every corner and is changing all the way through each one. The heading change differs too, and it goes by which leg the turn touches: a turn that begins or ends on the downwind leg is more than 90 degrees, and a turn that begins or ends on the upwind leg is less than 90. In the clean case the amount over or under is the crab angle you are carrying on the crosswind leg.

1. Downwind to base. Highest groundspeed of the maneuver, so this is the steepest bank, and more than 90 degrees of heading change, because the turn leaves the downwind leg.
2. Base to upwind. Groundspeed falling, so the bank shallows. Less than 90 degrees, because the turn ends on the upwind leg.
3. Upwind to crosswind. Slowest groundspeed, shallowest bank of the four. Less than 90 degrees again, because the turn leaves the upwind leg.
4. Crosswind to downwind. Groundspeed building back up, so the bank steepens. More than 90 degrees, because the turn ends on the downwind leg.

Do not memorize the list. Memorize the two rules underneath it: bank follows groundspeed, and a turn touching the downwind leg is more than 90 degrees while a turn touching the upwind leg is less. Then fly the course both directions, so the shape lives in your eyes and not in a left-hand habit.

What goes wrong

Almost every fault is late wind correction. You wait until you can see yourself off the line, then put in a large correction, which throws the next corner off, and the rectangle turns into a lopsided oval. The fix is to decide what the wind will do to the next leg before you roll out onto it.

The second is over-controlling — abrupt, large inputs chasing a track that is only slightly wrong. A small correction held is always better than a big one taken out again.

The third is attention. Eyes outside is correct, but altitude and airspeed drift while you are looking at the field, so trim the airplane properly and let the scan come back inside briefly and often. Fixating on the reference costs you the traffic scan, the altitude and the coordination all at once.

Flown to standard, the course holds altitude within 100 feet and airspeed within 10 knots, the ball stays centered through the corners, and the track is a rectangle someone on the ground would recognize as one. Those two numbers are the Private Pilot ACS tolerances for Ground Reference Maneuvers, Task PA.V.B; check the current ACS for the certificate you are flying for, since the wording and the numbers do get revised.

Where you meet it next

You meet it on every landing you make. What this maneuver does is make visible the corrections a pattern hides, and the wind that crabs you down a crosswind leg is the same wind you resolve into a crosswind component on final. Read it before you go: the wind group in a METAR is where the day's drift starts. On the flight instructor side it sits under Ground Reference Maneuvers in the Flight Instructor for Airplane ACS, FAA-S-ACS-25, and the examiner watches your coordination in the corners more than the neatness of the rectangle.

It is also the first of a set. S-turns across a road and turns around a point ask the same question — bank against groundspeed — with a curve in place of a corner, and eights on pylons adds altitude to the answer. Those three, and the normal and crosswind approach and landing where all of it finally gets used for real, are in the lesson index.