Private pilot · ACS PA.VIII.C
Constant Airspeed Descents (Instruments)
A constant airspeed descent by instruments: reduce power, hold airspeed with pitch, and level off on altitude.
Why this one matters
Descending below a cloud layer may seem like the way out of IMC, but a descent into unknown terrain is how many VFR-into-IMC accidents end. Controlled descents matter, and so does knowing when it’s safe to descend at all.
Can’t miss
- •To start a descent at your cruise airspeed, reduce power and lower the nose together to the attitude that holds it. To descend slower than cruise, reduce power, hold altitude while the airspeed decays, and lower the nose as the target speed approaches. Then trim, on the assigned heading, coordinated: establish, trim, cross-check, adjust.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- •Pitch holds the airspeed; power sets how fast you descend.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- •Leveling at the descent airspeed: start about 10% of the vertical speed early (50 feet at 500 fpm), raise the pitch to the level attitude and add power to the level-flight setting together, then trim and cross-check. Leveling at a faster cruise speed: add power about 100 to 150 feet early, hold the descent attitude while the speed builds, then pitch to level.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- •Descending turns: rolling in reduces the vertical lift, so the descent rate increases; expect a small power increase and a pitch check to hold the rate and airspeed. Keep it coordinated at no more than standard rate, lead the rollout to the heading, and coordinate the rollout with the level-off.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- •The minimum safe altitude is a floor you never descend below blind, not permission to descend looking for VFR. In cloud, stay at or climb to a safe altitude, turn back to VMC if it's safely possible, and get ATC help early.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures (inadvertent flight into IMC); AIM, Chapter 6, Emergency Procedures)
- •Spatial disorientation can make a descending turn feel level: watch the attitude indicator.(PHAK (FAA-H-8083-25C), Aeromedical Factors)
- •Checkride standard: level off within ±200 feet, heading ±20°, airspeed ±10 knots.(Private Pilot ACS (FAA-S-ACS-6C), PA.VIII.C.S3)
What you should know
The instruments and the scan K1 · R5 · R6
- Attitude instrument flying uses control instruments (the attitude indicator and the power instruments) to set pitch, bank and power, and performance instruments (altimeter, airspeed, VSI, heading indicator, turn coordinator) to check the result.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Scan with the attitude indicator at the center: glance out to each performance instrument and back to the attitude indicator, adjusting as needed.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Three scan errors: fixation (staring at one instrument), omission (leaving one out) and emphasis (relying on one instead of cross-checking).(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Primary and supporting instruments: for each of pitch, bank and power, one instrument is primary (the one that shows the target you're holding) and others support it. In level flight, the altimeter is primary for pitch, the heading indicator for bank, and the airspeed indicator for power; each lesson below gives its own set. Use it alongside the control-and-performance method.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Know each instrument's limits. Heading indicator: it precesses, so realign it with the compass about every 15 minutes, only in straight, level, unaccelerated flight. Attitude indicator: a vacuum or electric gyro (check the suction gauge or power source) with pitch and bank limits, beyond which it can tumble. VSI: lags 6 to 9 seconds and shows a trend; confirm it on the altimeter and attitude indicator. Altimeter: only as good as its setting. Compass: turning (undershoot north, overshoot south) and acceleration errors.(Instrument Flying Handbook (FAA-H-8083-15B), Flight Instruments)
- A failing instrument shows up as disagreement: if the attitude indicator disagrees with the turn coordinator, altimeter and VSI, suspect it. Pitot-static blockages: a blocked static port freezes the altimeter and zeros the VSI (airspeed is right only at the altitude where it blocked); a blocked pitot (with the drain blocked) makes the airspeed act like an altimeter. Use the alternate static source if fitted.(Instrument Flying Handbook (FAA-H-8083-15B), Flight Instruments; PHAK (FAA-H-8083-25C), Flight Instruments)
Controlling the airplane by instruments R7 · R8
- Learn your airplane's numbers: the attitude picture and power setting (RPM or manifold pressure) for level cruise, climb and descent. Attitude plus power gives predictable performance: set that combination first, trim, then cross-check and adjust only slightly.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Make small, smooth pitch and bank changes on the attitude indicator, then let the airplane settle and check the performance instruments before the next change. Size them: for an altitude error of 100 feet or less, about a half bar-width of pitch; more than 100 feet, a full bar-width until within 100, aiming for a VSI rate about double the error (150 feet high: about 300 fpm down). For heading, a bank about equal to the degrees of error, never more than standard rate.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Trim off control pressure for every sustained attitude or power change: a trimmed airplane holds attitude while you scan and do other tasks. For a brief turn, hold the extra pressure by hand instead; if you do trim for it, take the trim out on rollout.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
- Keep the ball centered with rudder: uncoordinated flight makes heading and attitude harder to hold.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
Why a VFR pilot trains this R1 · R2 · R3 · R4
- The goal is to escape instrument conditions you entered by accident, not to fly in them. VFR into IMC kills through spatial disorientation and loss of control, often within a few minutes.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures (inadvertent flight into IMC))
- Your inner ear can’t sense slow turns or tell a turn from a climb: the leans, the graveyard spiral and false climb sensations. Trust the instruments, not the feeling.(PHAK (FAA-H-8083-25C), Aeromedical Factors)
- Fatigue and stress make it worse. The escape, in order: aviate first (wings level on the attitude indicator, your known attitude and power, trimmed, ball centered, and don't turn while you're still stabilizing); hold altitude, or climb to a safe altitude if terrain clearance is in doubt (the minimum safe altitude is a floor you never descend below blind, not a reason to descend looking for VFR); then turn toward known VMC, with a standard-rate 180 only if clear weather is known to be behind you; and call ATC early, confess, and declare an emergency if it's deteriorating (121.5 and 7700 if you can't reach anyone). If it keeps getting worse, an off-airport precautionary landing in VFR conditions may be the safest option left.(Airplane Flying Handbook (FAA-H-8083-3C), Emergency Procedures (inadvertent flight into IMC); AIM, Chapter 6, Emergency Procedures)
- ATC radar can help a VFR pilot in difficulty only with two-way radio and within radar coverage; the help is advisory, doesn't authorize breaking a rule, and safe flight stays your responsibility. Tell them you aren't instrument rated, and choose a course to a VFR landing.(AIM 6-2-1)
- Under the hood or in clouds you can’t see other aircraft, terrain, obstacles or wires. In training, the safety pilot looks out; in real IMC, fly a known safe altitude and heading that clears terrain and obstacles. ATC traffic help doesn't guarantee terrain clearance.(AC 90-48, Pilots' Role in Collision Avoidance)
- When you’re overloaded, prioritize: keep the wings level and the attitude steady first, then navigate and talk.(Risk Management Handbook (FAA-H-8083-2A))
Primary instruments in the descent K1
- In a stabilized constant-airspeed descent: airspeed indicator primary for pitch, heading indicator primary for bank, manifold pressure or tachometer primary for power; the attitude indicator, altimeter, VSI and turn coordinator support.(Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying)
On the flight
ACS standards
- Level off at the assigned altitude and maintain altitude ±200 feet, heading ±20°, airspeed ±10 knots.(Private Pilot ACS (FAA-S-ACS-6C), PA.VIII.C.S3)
What your instructor is watching for
Your instructor watches a smooth power reduction, steady airspeed control, coordination in turns, and a level-off that leads the altitude with power added on time.
Scenarios
Decide what you would do first, then see the worked answer.
Descending at 500 fpm, the airspeed keeps creeping up.
What do you do? See the worked answer
Raise the nose slightly to hold the airspeed, and reduce power a bit if you want the same descent rate.
Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying
Leveling off at 3,000 feet from a 600 fpm descent.
When do you start? See the worked answer
About 60 feet early, around 3,060 feet, adding power as you raise the nose.
Instrument Flying Handbook (FAA-H-8083-15B), Airplane Attitude Instrument Flying
A descending turn in cloud feels like level flight.
What’s happening? See the worked answer
A graveyard spiral starting: in a prolonged turn the inner ear stops sensing it (the somatogyral effect), so it feels level while the airplane descends in a tightening turn; pulling back only tightens it. Recover in order: reduce power, level the wings with coordinated aileron and rudder on the attitude indicator, then gently raise the nose to level. (The leans are different: a false sense of bank after rolling out of a turn you didn't notice.)
PHAK (FAA-H-8083-25C), Aeromedical Factors
Common mistakes
Descending without knowing what’s below.
CFIT.
Instead: Know the minimum safe altitude and the terrain before you descend.
Forgetting power at level-off.
Airspeed decays below cruise.
Instead: Add power as you raise the nose.
Pitching for descent rate.
Airspeed goes off.
Instead: Pitch for airspeed, power for descent rate.
Now train it
Say it out loud, hear it asked, and take the quick check in this lesson’s practice pack. It tracks your shaky spots.
Got it?
When it feels solid, practice constant airspeed descents (instruments) out loud with our examiner.
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Go to the source (free)
Teaching this? The instructor lesson plan →
Sources
- Instrument Flying Handbook (FAA-H-8083-15B): Flight Instruments; Airplane Attitude Instrument Flying; Human Factors
- Airplane Flying Handbook (FAA-H-8083-3C): Emergency Procedures (inadvertent IMC)
- Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C): Flight Instruments; Aeromedical Factors
- Aeronautical Information Manual (AIM): Chapters 4 and 6
- Private Pilot ACS (FAA-S-ACS-6C): Area VIII
Study aid, not FAA guidance. Regulations change; check the current text at eCFR and the ACS. Checked against current sources 2026-11-12.