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Turns to Headings

A turn to a heading on instruments is the same turn you already fly, with the horizon taken away. It is the maneuver that decides whether an accidental cloud entry stays a heading change or becomes a spiral.

Basic Instrument Maneuvers — FI.XI.D

Why the maneuver exists

You end up here by accident. The night got darker than expected and the cloud you thought you were under is now around you, the weather went down faster than forecast, or the temperature slid the last degree to the dewpoint and fog formed underneath you. Continued visual flight into instrument conditions is one of the most lethal things a general aviation pilot can do, and not because the airplane stops flying. It is because the pilot stops being able to tell which way is up.

Your inner ear cannot detect a slow, steady roll. Once the horizon is gone it will report level flight while the airplane is banking, and it will keep reporting level flight while the bank steepens, the nose drops and the speed builds. That is the spiral, and it is what the maneuver is trained to prevent.

The other reason is practical. Getting out of an accidental cloud entry usually starts with a turn — a reversal back toward the air you were just in, or a heading a controller gives you — but it is rarely only a turn. The same guidance has you climb to an altitude that clears the terrain and obstacles around you, and the reversal assumes the air behind you is still the air you left, which after a few minutes of a closing sky it may not be. What stays true is that a heading change is the one thing you have to be able to fly while reading nothing but the panel.

Settle one thing before any of the rest. Practicing this is simulated instrument flight, and 14 CFR 91.109 does not let you do it alone. Under a hood or any other view-limiting device you need an appropriately rated safety pilot in the other seat of an airplane with dual controls, or an instructor. Everything below assumes there is one aboard.

What the instruments are telling you

Three of your instruments run on air pressure: the airspeed indicator from pitot and static pressure, the altimeter and the vertical speed indicator from static alone. Three run on gyros, or on the solid-state attitude reference that replaced them on a glass panel: the attitude indicator, the heading indicator and the turn coordinator.

The inclinometer — the ball in its curved glass tube, usually sitting under the turn needle — belongs to neither group. It is liquid, gravity and inertia, with nothing spinning inside it and nothing powering it, which is why it keeps telling you the truth about coordination after the vacuum pump seizes or the attitude and heading reference system drops offline. Note that now, because it is part of what you are left with later.

A glass panel rearranges that information rather than changing it: attitude in the middle, airspeed tape left, altitude tape right, HSI along the bottom, turn rate under the bank pointer. Engine indications move off to the MFD, which is exactly why pilots forget to look at them.

Keep three of them separate in your head, because they answer different questions. The attitude indicator tells you how much bank you have. The turn rate indicator tells you how fast the heading is changing. The ball tells you whether the airplane is coordinated. And the trend vectors on the tapes are a prediction, not a measurement — fly the number, and use the trend only to see where the number is going.

The scan

Work the panel as a hub and spokes. The attitude indicator is the hub: you set an attitude there, go out to one other instrument to see what that attitude produced, and come straight back. Out and back, in no fixed order — whatever the task makes most important gets looked at most often, and the engine indications stay in the loop even though they are on the other screen.

What you must not do is stop on one tape and watch it. Staring at the altimeter while it unwinds does not fix the altitude; going back to the attitude indicator and setting the pitch does.

Flying the turn

The unit you turn in is the standard rate turn: three degrees per second, a full 360 in two minutes. That rate is what makes an instrument turn predictable, because it converts a heading change into a number of seconds — ninety degrees takes thirty seconds, whatever the airplane.

The bank that produces three degrees per second depends on how fast you are going. The rule of thumb is roughly fifteen percent of true airspeed, so a trainer needs a shallow bank and a faster airplane a steeper one — but the relationship does not run on forever. The handbooks hold the bank used for a standard rate turn to about 25 to 30 degrees, and where the speed would call for more than that, roughly above 250 knots true, the answer is half standard rate rather than more bank. Set bank on the attitude indicator, then adjust it against the turn rate indicator until the needle or trapezoid sits on the standard rate mark.

1. Read your present heading and the assigned one, and turn the shorter way.
2. Roll in smoothly with aileron and rudder together, ball centered.
3. Add back pressure as the bank builds — the vertical component of lift is shrinking and the altitude will go before anything else does.
4. Adjust bank until the turn rate indicator shows standard rate, and hold the control pressures rather than trimming them away. A ninety-degree turn lasts thirty seconds, and trim you wind in going round is trim you have to wind out rolling level. Trim for a turn only when you are going to be in it for a while.
5. Scan out and back — altitude, airspeed, rate, ball, heading — correcting small deviations early rather than large ones late.
6. Lead the rollout by about half the bank angle, and roll out coordinated, releasing the back pressure as the wings come level.

Hold heading within 10 degrees, altitude within 100 feet and airspeed within 10 knots. Those are at least as tight as any version of the standard you will be tested against, so flying to them keeps you inside all of them — but read the ACS for your own certificate for the numbers that count.

What goes wrong

Failing to lead the rollout is one of the errors the handbooks list for this maneuver, and it is self-inflicted: at three degrees per second the heading keeps moving while you level the wings, so arriving wings-level on the target means starting early. Chasing the overshoot then costs you altitude, which costs you airspeed, and now you are fixing three things instead of one.

The rest cluster around the scan. Locking onto one moving tape, believing a trend vector instead of the rate, dropping the engine indications out of the loop, and misreading unfamiliar symbology all produce the same thing — a control input made from incomplete information. Rough or uncoordinated inputs make it worse, because every correction made with a jerk hands you a new deviation to chase.

When the panel quits

Know your airplane's failure indications before you need them, and know that they are not common property across manufacturers. On a Garmin G1000 a lost sensor shows as a red X over the affected display, and a failed PFD is handled with reversionary mode, which rebuilds the primary display on the remaining screen. Avidyne, Dynon, Aspen and the rest annunciate failures and revert to backup displays in their own ways, and the airplane's flight manual supplement for the panel you actually fly is where to learn yours. What does not change is the fallback: know how to fly the same turn partial panel, with the turn rate indicator and the ball standing in for the attitude picture and the altimeter and airspeed doing the pitch work.

Use the autopilot if it is working and you understand its modes — it reduces workload, it does not make decisions, and you should know how it disengages before you need that.

Then use the controller, and use them for what the situation actually is. A VFR pilot in instrument conditions is an emergency, and the FAA's guidance is to treat it as one in the first minute rather than the tenth. Declare it — mayday if you are in distress, pan-pan if it has not gone that far — and then say plainly that you are VFR in instrument conditions and ask for vectors to visual conditions. Declaring is what buys you priority handling, terrain and obstruction advisories, and a controller working your problem rather than fitting you into the flow. Under 91.3(b) you may deviate from any rule to the extent required to meet the emergency, and the consequence people worry about is a written report, submitted only if the administrator asks for one. The words most pilots have rehearsed, unable VFR, request vectors, are still worth saying — after the declaration, not instead of it.

Where you meet it next

Turns to headings sit in the basic instrument maneuvers block on the checkride, alongside straight-and-level, climbs and descents, and recovery from unusual attitudes. The examiner asks for them under a view-limiting device one after another, so what is really being tested is the scan. The standard rate turn is then the building block of every instrument procedure you fly later — holding entries, procedure turns and vectors to final are all this maneuver with a clock or a course needle attached. In the ground school library, Instrument Straight-and-Level Flight sets up the scan this lesson borrows, Constant Airspeed Climbs and Descents adds the vertical half, Recovery From Unusual Flight Attitudes is where the spiral in the first section gets undone, and Systems and Equipment Malfunctions goes further into the partial-panel case. The weather lessons there cover the conditions that put you here in the first place.