Instrument Flight

• Altitude ±100 feet during level flight
• Selected headings ±10°
• Airspeed ±10 knots
• Bank angles ±5° during turns

The examiner is also grading the process — proper cross-check, interpretation, and pitch/bank/power/trim corrections (IR.IV.A.S2).

Control and performance — set an attitude on the attitude indicator and a power setting, then confirm the result on the performance instruments.

Primary and supporting — for each maneuver, classify instruments by control function: one instrument is primary for pitch, one for bank, one for power, and the rest support it.

Both use the same instruments and the same control responses — they differ in how much they lean on the attitude indicator versus interpreting the others (IFH ch. 6).

Three groups:

• Control — immediate attitude and power indications: attitude indicator plus power indicators (manifold pressure, tachometer, fuel flow)
• Performance — what the airplane is actually doing: altimeter, ASI, VSI
• Navigation — position relative to a facility or fix

Four steps: establish an attitude and power setting on the control instruments, trim until control pressures are neutralized, cross-check the performance instruments for the desired result, and adjust attitude and/or power as necessary (IFH ch. 6).

The primary instrument gives the most pertinent information for the maneuver — usually the one that should hold a constant indication. In straight-and-level flight:

• Altimeter — primary for pitch
• Heading indicator — primary for bank
• Airspeed indicator — primary for power

The attitude indicator and the rest support them (IFH ch. 6).

Eyes stay on the attitude indicator 80–90 percent of the time, with quick glances out to one performance instrument and back — AI, altimeter, AI, heading indicator, AI, airspeed, and so on. The eyes never travel directly between the flight instruments; the AI anchors the scan because it is the one instrument showing pitch and bank in a single glance. The maneuver determines which instruments join the pattern (IFH ch. 6).

• Fixation — staring at a single instrument, e.g., wondering how the altimeter got 200 feet low while heading wanders off
• Omission — dropping an instrument, e.g., leveling off a steep turn on the AI alone and missing the heading drift caused by its precession error
• Emphasis — relying on the instrument that is easiest to read instead of the combination; the AI alone can't hold altitude with precision (IFH ch. 6)

3° per second — a complete 360° circle in 2 minutes. The bank required increases with speed: rule of thumb is 15 percent of true airspeed, computed by dividing airspeed by 10 and adding half the result — at 100 knots about 15° (100 ÷ 10 = 10 + 5), at 120 knots about 18°. Roll in on the attitude indicator, then hold the turn coordinator's standard-rate indication as primary bank (IFH ch. 7).

Start the level-off at about 10 percent of the vertical speed — climbing at 500 fpm, lead by 50 feet; at 1,000 fpm, lead by 100 feet. Same rule applies to leading the roll-out of a turn: lead the desired heading by half the bank angle (IFH ch. 7).

A warning flag or an inconsistency between the attitude indicator and the supporting performance instruments. Maintain aircraft control first, expedite the cross-check to include every instrument, and compare the AI against the turn indicator and VSI — that comparison checks the vacuum/pressure, electrical, and static systems against each other so you can isolate the failed component and fly on what remains (IFH ch. 11).

Once the airplane stabilizes at climb speed and attitude:

• Airspeed indicator — primary for pitch (airspeed is what you're holding; small pitch changes correct it)
• Heading indicator — primary for bank, as in straight-and-level
• Tachometer or manifold pressure — primary for power, confirming the climb power setting

During the entry itself, before things stabilize, the attitude indicator is your pitch reference while the ASI catches up (IFH ch. 7).

As power comes up, the ASI is primary for pitch until the vertical speed approaches the target. Once the VSI needle stabilizes, the roles swap: VSI primary for pitch, ASI primary for power — you hold the rate with pitch and the airspeed with power. Prompt, closely coordinated pitch-and-power corrections are the whole game: vertical speed correct but airspeed low — add power; vertical speed high and airspeed low — lower the nose slightly first (IFH ch. 7).

Entry — effective with or without an attitude indicator: reduce airspeed to the selected descent speed in level flight, then make a further power reduction to a predetermined setting, simultaneously lowering the nose to hold airspeed constant, and trim off the pressures.

Constant-airspeed descent: any deviation from the desired airspeed calls for a pitch adjustment (ASI primary for pitch).

Constant-rate descent: same entry, but the VSI becomes primary for pitch once it stabilizes near the target rate, and the ASI primary for power — closely coordinated pitch-and-power corrections, just as in climbs.

Leveling off at an airspeed higher than descent speed takes more lead — at 500 fpm, about 100–150 feet; leveling off at descent airspeed, about 50 feet, adding power as the pitch comes up (IFH ch. 7).

• Turn coordinator — primary for bank (the AI supports it; note the AI's bank angle when the TC shows standard rate)
• Altimeter — primary for pitch
• ASI — primary for power; as bank steepens, vertical lift decreases and drag rises, so expect a pitch and power touch-up

Rolling out, the AI becomes primary bank until roughly level, then the heading indicator takes over. In a timed turn, the clock replaces the heading indicator — at standard rate the airplane turns 45° in 15 seconds (IFH ch. 7).

The common procedure is to underpower or overpower the target power setting — overshoot it to accelerate the airspeed change, then set the known cruise value — while the altimeter stays primary for pitch and the heading indicator stays primary for bank throughout. During the change the manifold pressure gauge (or tachometer) becomes primary for power; once airspeed settles, the ASI takes the role back. Expect trim and control-pressure changes around all axes as power changes — a single-engine airplane yaws and rolls left as power comes in — so cross-check speed has to rise (IFH ch. 7).

• Older (spillable) units tolerated only about 60° of pitch and 100° of roll — beyond that the gyro tumbled, hence the caging mechanism; newer instruments do not have these tumble limits
• Gyro erection takes 2–3 minutes after start (up to 5)
• Slight nose-up indication during rapid acceleration, nose-down during rapid deceleration
• Small pitch-and-bank error after a 180° turn — these inherent errors self-correct within about a minute of straight-and-level flight (IFH ch. 5)

VSI: the pointer lags a few seconds behind the actual pressure change, but it is more sensitive than the altimeter and excellent as a trend instrument; an IVSI (instantaneous VSI) uses accelerometer-driven pumps to remove most of the lag. If the VSI shows a small climb or descent in known level flight, it's out of calibration — use that indication as your zero.

ASI: lags on pitch changes, not from instrument construction but from the airplane's momentum: a rapid airspeed change means a large pitch change happened a moment ago (IFH ch. 5, ch. 7).

A non-slaved gyro heading indicator isn't north-seeking — you set it from the magnetic compass. The Earth rotates 15° per hour while the gyro holds its position in space, producing apparent drift, on top of mechanical precession. Standard practice: compare it with the magnetic compass at least every 15 minutes (in straight, level, unaccelerated flight) and reset as necessary (IFH ch. 5).

The semicircular canals sense angular acceleration through fluid deflecting sensory hairs. In a prolonged constant-rate turn the fluid catches up with the canal walls, the hairs straighten, and the brain concludes the turn has stopped. Rolling out then swings the fluid the opposite way — a false sensation of turning in the opposite direction — and the disoriented pilot may roll right back into the original turn. The otolith organs add their own lie: forward acceleration feels like tilting the head back, i.e., a false climb (IFH ch. 3).

Illness, medication, alcohol, fatigue, sleep loss, and mild hypoxia all increase susceptibility to spatial disorientation — being physically tuned for flight is a listed countermeasure, not a nicety. In flight:

• Avoid sudden head movements, especially during takeoff, turns, and approach
• If you drop something, retrieve it with minimal head movement (coriolis)
• Use only reliable fixed points when outside references are available
• Above all, become proficient on the instruments and trust them over your sensory perceptions — the sensations can't be prevented, only overridden (IFH ch. 3)

Flying an electronic-flight-display airplane without using the autopilot has been shown to increase workload and decrease situational awareness for pilots still learning the system — the scan you've automatized on round dials doesn't transfer for free to tapes and trend vectors. The flip side is also tested: the autopilot should be used to reduce workload, which buys attention for monitoring the flight. Know the display, the failure annunciations, and the automation modes before you take an unfamiliar panel into IMC (IFH ch. 6, ch. 7).