Straight-In Autorotation in a Single-Engine Helicopter

Objective

The student will develop and demonstrate proficiency in executing a straight-in autorotation to a power recovery from at least 500 feet AGL in a single-engine helicopter. Upon completion, the student will be able to:

• Explain the aerodynamic principles of autorotative flight, including energy management, rotor RPM control, and the effects of environmental conditions (wind, temperature, density altitude, gross weight)
• Demonstrate proper procedure for initiating, flying, and recovering from a straight-in autorotation
• Maintain main rotor RPM (Nr) within normal limits throughout the maneuver
• Establish and maintain autorotation airspeed ±5 knots
• Compensate for wind drift to arrive at the intended touchdown point
• Execute proper deceleration and flare to achieve safe tail boom clearance
• Terminate the autorotation to a stabilized hover within 100 feet of a designated point
• Identify and mitigate risks associated with autorotative flight, including low rotor RPM, excessive descent rates, collision hazards, and loss of situational awareness

ACS Reference: CH.VIII.B – Straight-In Autorotation in a Single-Engine Helicopter

Content

Regulatory Foundation

14 CFR 61.127(b)(1) requires that commercial helicopter applicants receive training in autorotations, including power-off 180-degree autorotations. The straight-in autorotation is a fundamental emergency procedure that commercial pilots must execute with precision, as they may be required to demonstrate this skill during passenger operations, aerial work, or when conducting external load operations under 14 CFR 133.

14 CFR 91.119 governs minimum safe altitudes, which becomes critical when practicing autorotations. Commercial pilots must ensure sufficient altitude exists to complete the maneuver safely and comply with the requirement that helicopters be operated at an altitude allowing an emergency landing without undue hazard to persons or property on the surface.

Aerodynamic Principles of Autorotation

An autorotation is a powered-off descent condition where the main rotor is driven solely by upward airflow through the rotor system. When engine power is lost or deliberately reduced to flight idle, the collective must be lowered immediately to maintain rotor RPM. This reduces blade pitch angle and allows the relative wind—now coming from below—to keep the rotor turning.

The rotor disk divides into three aerodynamic regions during autorotation:

1. Driven Region (outer 30% of blade): Produces forces that tend to slow the rotor due to high induced drag
2. Driving Region (middle 30-50% of blade): The resultant aerodynamic force has a forward component that drives rotor rotation
3. Stall Region (inner 25% near hub): Low relative velocity results in stalled airflow; produces minimal useful force

The driving region provides the autorotative force. During steady-state autorotation, the accelerating forces from the driving region equal the decelerating forces from the driven and stall regions, maintaining constant rotor RPM.

Energy Management: An autorotation is fundamentally an energy management exercise. At entry, you possess potential energy (altitude) and kinetic energy (forward airspeed and rotor RPM). Your goal is to convert these energy stores efficiently to achieve a controlled landing or power recovery.

• Potential energy = altitude: This is your primary energy reserve. Higher entry altitude provides more time and options.
• Kinetic energy = rotor RPM + airspeed: Rotor RPM is stored energy that will be converted to thrust during the flare. Airspeed provides energy that can be traded for rotor RPM during deceleration.

You cannot create energy in an autorotation—only manage what you have. Every action is a trade: lowering the nose trades altitude for airspeed; raising collective trades rotor RPM for lift.

Effects of Environmental Conditions

Wind: Wind significantly affects glide distance and ground track. A headwind increases groundspeed difference from airspeed, steepening the glide angle over the ground but increasing total glide distance available. A tailwind decreases effective glide distance. Crosswinds require continuous drift correction to track toward the intended touchdown point.

Think of it this way: You’re always gliding through the air mass at a specific airspeed. But the air mass itself is moving relative to the ground. If that air mass is moving toward your target (headwind), you cover more ground distance even though your airspeed remains constant.

Weight (Gross Weight): Increased weight increases the descent rate for a given airspeed because more lift is required to support the helicopter. A heavier helicopter has greater momentum and stores more kinetic energy, which can be beneficial during the flare. However, the increased disc loading (weight divided by rotor disc area) results in a higher rate of descent throughout the autorotation.

Lighter helicopters descend more slowly but have less kinetic energy available during flare—the flare must be initiated earlier and executed more gently to avoid rotor RPM decay.

Temperature and Density Altitude: High density altitude reduces air density, which degrades rotor efficiency. At high density altitudes:

• The rate of descent increases for a given airspeed
• Rotor RPM is more difficult to maintain in the normal range
• Less lift is generated during the flare for a given collective pitch application
• Power available for recovery is reduced (critical consideration for practice autorotations)

High-density-altitude autorotations require earlier flare initiation and more aggressive flare application. Commercial pilots must be particularly cautious when conducting aerial work or external load operations at high gross weights in high-density-altitude conditions—the margin for error decreases dramatically.

Real-world scenario: On a hot summer day in the mountains (high density altitude), conducting external load operations at max gross weight, your autorotative descent rate could be 2,000-2,500 FPM instead of the sea-level book value of 1,600-1,800 FPM. Your flare effectiveness is reduced, and you have minimal power available for a go-around. This is why density altitude calculations aren’t academic exercises—they directly affect your survival margin.

Main Rotor RPM (Nr) Management

Maintaining rotor RPM within normal operating limits (typically green arc on tachometer) is paramount. Rotor RPM is your stored energy reserve for the flare and landing.

Low Rotor RPM or Rotor Stall: If RPM decays below the normal range:

• Available rotor thrust decreases
• Flare effectiveness is severely compromised
• A rotor stall can occur where retreating blade stall develops across the entire disc
• Recovery requires lowering collective immediately and lowering the nose to accelerate airflow through the rotor
• In extreme cases, rotor RPM may decay to the point where recovery is impossible

Causes of low rotor RPM:

• Excessive collective pitch (too much blade angle for the energy available)
• Airspeed too slow (insufficient upward airflow through rotor system)
• Aft cyclic input that reduces airflow velocity through rotor
• High gross weight or high density altitude (increased power demands)

Rotor RPM Overspeed: Exceeding maximum RPM limits can occur if:

• The nose is lowered excessively, increasing airflow velocity
• Airspeed becomes excessive (beyond Vne)
• Collective is reduced too aggressively during entry
• Forward cyclic is applied abruptly

Rotor overspeed risks mechanical damage to the rotor system, mast, transmission, and other dynamic components. Monitor rotor RPM continuously using the tachometer and correlate with engine RPM during powered flight.

Rotor RPM Control Inputs:

• Collective: Primary control for rotor RPM in autorotation. Lowering collective decreases blade pitch, reducing drag and allowing RPM to increase. Raising collective increases blade pitch, increasing drag and decreasing RPM.
• Cyclic (Pitch Attitude/Airspeed): Lowering the nose increases airflow velocity through the rotor, increasing RPM. Raising the nose decreases airflow, decreasing RPM.
• Pedals: Necessary to maintain heading, but have minimal direct effect on rotor RPM

Effect of Bank Angle and Airspeed Variations

Bank Angle: Turning in an autorotation requires increased rotor thrust to maintain altitude (or accept an increased descent rate). Since no power is available, any turn will:

• Increase descent rate
• Require lowering the nose to maintain rotor RPM (trading altitude for energy)
• Decrease available energy for flare and landing

Steep turns in autorotation are dangerous and should be avoided. If turns are necessary (e.g., to avoid obstacles or compensate for wind drift), use shallow banks (15-20 degrees maximum) and accept the increased sink rate. Anticipate the need to lower the nose slightly to maintain rotor RPM during the turn.

Airspeed Variations:

• Below recommended autorotation airspeed: Reduced upward airflow decreases rotor efficiency. Descent rate increases dramatically. Rotor RPM becomes difficult to maintain. This is the settling-with-power region—avoid it.
• At recommended autorotation airspeed (typically 60-70 KIAS depending on helicopter model): Optimal balance between descent rate, rotor efficiency, and energy available for flare. This is typically close to best glide speed.
• Above recommended autorotation airspeed: Increased parasite drag increases descent rate despite improved rotor efficiency. Risks approaching or exceeding Vne. However, higher airspeed provides more kinetic energy available for conversion to rotor RPM during flare.

The POH/RFM specifies recommended autorotation airspeed based on manufacturer testing for optimal glide performance.

High Descent Rate: Causes and Effects

High descent rates are dangerous because they:

• Reduce time available to identify and solve problems
• Increase ground impact velocity if flare is ineffective
• Increase likelihood of tail boom contact with terrain
• Decrease margin for error in flare timing and execution

Causes of excessive descent rate:

• Airspeed too slow or too fast (off the back side of the power curve)
• High gross weight
• High density altitude
• Turbulence and downdrafts
• Turning flight (bank angle)
• Aft cyclic (reducing forward airspeed and upward airflow)

If descent rate becomes excessive during an autorotation, evaluate immediately:

1. Is airspeed on target? Adjust pitch attitude as needed.
2. Is rotor RPM in the green arc? Adjust collective if needed.
3. Are you turning? Roll wings level.
4. If conditions don’t improve, consider power recovery immediately if altitude permits.

Risk Management Considerations

Low Entry Altitudes: Practicing autorotations below the manufacturer’s recommended entry altitude (typically 500 feet AGL minimum) leaves insufficient margin for error. If rotor RPM decays, airspeed deviates significantly, or a distraction occurs, insufficient altitude may exist to recover. For commercial training, use conservative entry altitudes that provide margin above the minimums.

Flight Control Inputs: Abrupt or improper control inputs can lead to:

• Rotor RPM excursions outside normal limits
• Excessive descent rates
• Loss of heading control
• Inability to reach the intended landing area

All inputs during autorotation must be smooth, coordinated, and deliberate. Avoid overcontrolling. Remember that the helicopter responds more sluggishly in autorotation due to reduced rotor thrust.

Turbulence and Wake Turbulence: Turbulence during autorotation destabilizes the helicopter and can cause:

• Sudden rotor RPM fluctuations
• Unpredictable descent rate changes
• Difficulty maintaining precise airspeed and heading
• Increased pilot workload

Avoid practicing autorotations in moderate or greater turbulence. Be particularly cautious of wake turbulence from other aircraft—helicopters are highly susceptible due to lower wing loading. Maintain awareness of other traffic and delay autorotation practice if necessary.

Windshear: A sudden change in wind speed or direction during autorotation (particularly during the flare) can cause:

• Unexpected changes in groundspeed and glide distance
• Airspeed fluctuations affecting rotor RPM
• Altitude loss or gain
• Difficulty achieving the intended touchdown point

Be alert for windshear indicators: sudden airspeed changes, vertical speed changes, or pitch/roll attitude changes without pilot input. If windshear is encountered, focus on maintaining rotor RPM and airspeed first, then reassess landing area as needed.

Powerplant Failure During the Maneuver: Although practicing autorotations with the engine at flight idle, an actual engine failure during practice is possible. Warning signs include:

• Unusual engine noises, vibrations, or smells
• Illuminated warning lights
• Loss of engine RPM indication
• Inability to add power during recovery

If an actual engine failure occurs during practice autorotation, continue the autorotation to the ground. Do not attempt to add power. Treat it as a real emergency and execute a full touchdown autorotation.

Collision Hazards: Autorotations are practiced in confined landing areas, often with obstacles present. Continuously evaluate:

• Proximity to wires, towers, buildings, trees
• Other aircraft in the practice area
• Vehicles or persons on the ground
• Animals that might move into the landing area

Maintain obstacle clearance throughout the descent. If obstructions compromise safety, execute a power recovery immediately.

Terminating an Autorotation: The transition from descent to power recovery or touchdown involves rapid control inputs and energy management. Risks include:

• Premature flare (excessive altitude loss after rotor RPM decay)
• Late flare (insufficient time to arrest descent, tail boom strike)
• Excessive collective application (rotor RPM decay)
• Insufficient collective application (hard landing)

Power Recovery and Go-Around: During the power application phase:

• Smoothly add power to avoid overtorquing or over-temping the engine
• Coordinate collective increase with power application
• Maintain rotor RPM by limiting collective application rate
• Be prepared for yaw due to torque increase—apply left pedal as needed
• Monitor engine instruments for normal indications during power increase

If the approach becomes unstable or unsafe, execute a go-around immediately. Brief all go-around criteria before beginning the maneuver.

Distractions, Task Prioritization, Loss of Situational Awareness, Disorientation: Autorotations are high-workload maneuvers requiring continuous attention to multiple parameters simultaneously:

• Rotor RPM
• Airspeed
• Altitude and descent rate
• Landing area alignment
• Wind drift correction
• Obstacle clearance

Distractions such as radio calls, cockpit alerts, or external events can lead to task saturation. Prioritize: maintain rotor RPM first, then airspeed, then navigate toward the landing area. If you become task-saturated or disoriented, execute a power recovery immediately if altitude permits. Situational awareness includes knowing your altitude AGL, distance to intended touchdown point, and energy state (rotor RPM + airspeed).

Procedure: Straight-In Autorotation to Power Recovery

Pre-Maneuver Preparation:

1. Complete pre-maneuver checklist (simulated emergency checklist readily available)
2. Select a suitable landing area: clear of obstacles, into the wind, with defined touchdown point
3. Clear the area: minimum two 90-degree clearing turns, check approach path and departure path
4. Make radio call: “[Location] traffic, [Callsign] practicing autorotations [location], [altitude]”
5. Position helicopter on downwind at pattern altitude (typically 500-700 feet AGL), aligned with intended ground track to landing area
6. Brief the maneuver: entry altitude, entry airspeed, target rotor RPM, recovery altitude (typically 50-100 feet AGL), go-around criteria

Entry (Simulated Engine Failure):

1. At the predetermined entry point (abeam touchdown point), smoothly roll throttle to flight idle or simulate engine failure per POH
2. Simultaneously: lower collective fully to maintain rotor RPM, apply right pedal to maintain heading (compensating for loss of torque)
3. Establish slight nose-low attitude to maintain/regain autorotation airspeed
4. Trim collective full down to reduce pilot workload
5. Verify rotor RPM in normal operating range (green arc)

Descent:

1. Maintain autorotation airspeed ±5 knots (per POH, typically 60-70 KIAS)
2. Continuously monitor rotor RPM—keep it in the green arc using small collective adjustments
3. Use cyclic to maintain ground track toward touchdown point, compensating for wind drift
4. Use pedals to maintain heading aligned with ground track
5. Monitor approach angle—should intercept a point approximately 50-100 feet prior to the intended touchdown point
6. Continuously assess: “Can I make the landing area? Do I need power now?”

Deceleration and Flare (50-100 feet AGL):

1. At approximately 50-100 feet AGL (specific altitude varies by helicopter model and conditions), initiate aft cyclic to begin deceleration
2. As airspeed decreases, the nose will rise—this is the flare
3. Progressively increase aft cyclic to trade airspeed for rotor RPM and lift
4. The flare should be aggressive enough to arrest descent rate but not so abrupt that excessive altitude is lost after rotor RPM peaks
5. Use pedals to maintain heading (right pedal requirement decreases as collective is raised)
6. Monitor rotor RPM—it will increase during the flare due to decreased collective and kinetic energy conversion

Power Recovery (10-20 feet AGL or as briefed):

1. At the predetermined recovery altitude (or when airspeed approaches translational lift speed), smoothly roll throttle to flight position while coordinating collective increase
2. Apply left pedal to compensate for increasing torque
3. Use collective to arrest descent and establish a hover
4. Avoid excessive collective application—let engine RPM stabilize and match rotor RPM before large collective movements
5. Adjust cyclic to maintain position over or near the intended touchdown point
6. Adjust pedals to maintain heading

Stabilized Hover:

1. Establish hover altitude (typically 3-5 feet AGL)
2. Position within 100 feet of the designated touchdown point (commercial standard)
3. Verify all engine parameters normal (RPM, temperatures, pressures)
4. Verify positive aircraft control in all axes
5. Make radio call if appropriate: “[Location] traffic, [Callsign] autorotation complete, remaining in the area”

Common Errors and Corrections

Schedule

Equipment

Required Aircraft Equipment

• Single-engine helicopter (per 14 CFR 61.45) with current airworthiness certificate, registration, and operating limitations
• Functional throttle governor or correlator (or capability to operate at flight idle)
• Functional rotor tachometer with clearly marked normal operating range
• Hobbs meter and tachometer for recording flight time
• Cockpit checklist or POH/RFM readily available
• Functioning radio for traffic calls

Required References (Instructor)

• FAA-S-ACS-16: Commercial Pilot – Rotorcraft Helicopter Airman Certification Standards (current edition)
• FAA-H-8083-21B: Rotorcraft Flying Handbook, Chapter 11 (Autorotation)
• FAA-H-8083-9B: Aviation Instructor’s Handbook, Chapter 9 (Teaching Practical Risk Management)
• Aircraft-specific POH/RFM: Autorotation procedures, limitations, airspeeds, and performance data
• 14 CFR Part 61: Certification: Pilots, Flight Instructors, and Ground Instructors (§61.127, §61.133)
• 14 CFR Part 91: General Operating and Flight Rules (§91.119, §91.3)

Required References (Student)

• POH/RFM for aircraft being flown
• Commercial Pilot Rotorcraft ACS (FAA-S-ACS-16)
• FAA-H-8083-21B: Rotorcraft Flying Handbook
• Autorotation emergency checklist (if not integrated in POH)

Training Aids and Materials

• Whiteboard or kneeboard for drawing autorotation profiles and energy management diagrams
• Rotor system diagram showing driven, driving, and stall regions
• High-altitude airport chart or density altitude calculator (for environmental effects discussion)
• Weight and balance form with multiple loading scenarios
• Video recording device (tablet/GoPro) for post-flight video debrief (optional but highly recommended)
• Model helicopter for demonstrating control inputs and rotor disc orientation (optional)

Logbook Requirements

Instructor must endorse student logbook per 14 CFR 61.189 for dual instruction given. Entry should reference autorotation training and note progression toward commercial certification standards.

Instructor Actions

1. Conduct preflight briefing covering the objective, ACS standards, risk management items, and completion standards. Use the whiteboard to diagram the three phases of autorotation: entry, descent, and recovery. Draw the rotor blade regions and explain how upward airflow drives the rotor during autorotation.

2. Explain energy management using an analogy: “Think of yourself starting at the top of a snowy hill on a sled. You have two energy reserves: your altitude (potential energy) and how fast you’re moving (kinetic energy). Your job is to trade these energy reserves efficiently to arrive at the bottom safely. If you waste altitude going too slow, you run out of energy. If you go too fast, you can’t control the landing. In the helicopter, rotor RPM is like having a flywheel on your sled—it stores energy you can trade for lift at the last second.”

3. Review environmental factors systematically:

   • Draw wind triangles showing headwind vs. tailwind effects on glide distance
   • Use weight and balance scenarios: “At 2,400 lbs vs. 1,800 lbs, how does descent rate change? Why?”
   • Calculate density altitude for current conditions and compare to sea-level performance: “Today we’re at 4,500 feet density altitude. Book value says 1,700 FPM descent at sea level. Expect 2,000+ FPM today. What does that mean for our flare initiation point?”

4. Demonstrate the complete maneuver in the aircraft with continuous narration:

   • “Clearing the area, two ninety-degree turns, looking for traffic and obstacles.”
   • “Radio call: ‘Springtown traffic, helicopter 123 practicing autorotations on the north ramp, 500 feet.’”
   • “Entry point: abeam the numbers, 500 feet. Simulated engine failure: throttle to flight idle—watch—collective down simultaneously, right pedal, slight nose-down for airspeed.”
   • “Rotor RPM, green arc, good. Airspeed coming to 65 knots. Trim collective.”
   • “Watch your ground track—wind is from the left, so I need a slight left cyclic input to track straight.”
   • “Monitoring rotor RPM constantly. Descent rate about 1,700 feet per minute today.”
   • “100 feet, starting the flare. Aft cyclic, progressively increasing. Watch rotor RPM climb as we convert airspeed to rotor energy.”
   • “50 feet, entering translational lift, adding power smoothly. Collective up, throttle to flight, left pedal for torque. Rotor RPM matching engine RPM.”
   • “Stabilizing in a hover, 3 feet, right over our touchdown point.”

5. Debrief the demonstration, emphasizing key decision points: “Notice I started the flare at 100 feet. That’s specific to this helicopter at this weight and density altitude. In denser air or lighter weight, I could start lower. In high-density altitude or heavy, I’d start higher. You need to calibrate this through practice.”

6. Set up the student for their first attempt using guided instruction:

   • “You have the controls. Set up on downwind, 500 feet, tracking parallel to the runway.”
   • “Your entry point will be abeam the numbers. I’ll call ‘simulated engine failure’ and you execute: throttle idle, collective down, right pedal, nose down for airspeed.”
   • “I’ll follow on the controls and guard for rotor RPM excursions. Your job: rotor RPM green arc, airspeed 65 knots, track toward the numbers.”

7. Provide real-time coaching during student execution:

   • “Rotor RPM a little high—raise collective slightly.”
   • “Airspeed 55 knots, we need 65—lower the nose a bit more.”
   • “Good, you’re drifting right—correct with left cyclic.”
   • “Descent rate looks good. Keep scanning: rotor, airspeed, ground track.”
   • “Approaching 100 feet, get ready to start your flare… now, aft cyclic.”
   • “More… more… watch the rotor RPM building. Good.”
   • “50 feet, add your power. Smooth on the throttle, collective coming up, left pedal.”

8. Critique each iteration immediately after landing:

   • “That was a solid first attempt. Your rotor RPM management was good—you caught the high RPM early. Your flare was a little late; we had 2,000 FPM descent at 75 feet. Next time, initiate at 100 feet. Your landing point was about 150 feet long. Wind correction needed earlier. Let’s do it again.”

9. Progressively reduce assistance as student demonstrates competency:

   • First attempt: follow on controls, provide continuous verbal cues
   • Second attempt: hands/feet near controls, verbal cues only at critical points
   • Third attempt: monitor only, intervene only if safety compromised
   • Fourth attempt: student briefs the maneuver, executes independently

10. Introduce abnormal situations after baseline proficiency is established:

    • “On this next one, I’m going to simulate low rotor RPM during descent. You’ll hear the low rotor horn. Show me your immediate corrective action.” (Instructor will simulate by calling “low rotor horn” without actually inducing low RPM)
    • “This time, as you start your flare, I want you to recognize you’re too high and execute a power recovery instead of continuing to a hover.”

11. Emphasize common student errors and corrections:

    • “I’m seeing you chase rotor RPM with large collective movements. Remember: small inputs, then pause and assess. The rotor has inertia—it takes time to respond.”
    • “You’re fixating on the landing area and ignoring rotor RPM. Eyes must move: rotor tach, airspeed, outside, rotor tach, airspeed, outside. That’s your scan pattern.”
    • “Your flare was too aggressive. You gained 200 feet of altitude, then ran out of rotor RPM. Flare needs to be progressive: start gentle, increase gradually as you get closer to the ground.”

12. Discuss risk management continuously:

    • “Notice we entered at 700 feet today, not 500. Why? High density altitude reduces our margin. If rotor RPM decays, we need altitude to recover.”
    • “If we were heavy today—say max gross weight—what would change? Descent rate increases, flare effectiveness decreases, power available for recovery is marginal. That’s why knowing your helicopter’s performance is critical.”
    • “What are our go-around criteria? I briefed three: rotor RPM below green arc and not recovering with corrective action, descent rate exceeding 2,500 FPM, or drifting more than 200 feet off course. If any of those happen, we add power immediately.”

13. Integrate decision-making scenarios:

    • “You’re in the descent, 300 feet AGL, and you notice a vehicle entering your landing area. What do you do?” (Expected answer: Execute power recovery immediately; do not continue the approach)
    • “You’re at 150 feet in the descent and rotor RPM starts decaying into the yellow arc despite full-down collective. What’s your immediate action?” (Expected answer: Lower the nose to increase airflow through the rotor, trading altitude for rotor RPM; if RPM doesn’t recover, execute power recovery immediately)

14. Conduct post-flight debrief using specific ACS criteria:

    • Review each maneuver execution against ACS standards (airspeed ±5 knots, rotor RPM in limits, landing within 100 feet)
    • Assign a grade: passing or additional training required
    • Document performance in instructor records and student logbook
    • Assign practice items: “For next lesson, review rotor RPM recovery techniques and practice mentally chairing through a complete autorotation while sitting in a chair at home. Visualize each control input and crosscheck.”

15. Provide encouragement and realistic feedback:

    • “You’re progressing well. Your first attempt was rough, but by the fourth iteration you were nailing the airspeed and rotor RPM. Your landing points are still inconsistent—that’s normal at this stage. Focus on wind correction earlier in the descent.”
    • “This is a challenging maneuver that requires constant practice. Even as a commercial pilot, you’ll need to practice autorotations regularly to stay sharp. The goal isn’t perfection today—it’s building the foundation of good technique.”

Student Actions

1. Review all assigned reading prior to the lesson: FAA-H-8083-21B Chapter 11 (Autorotation), POH/RFM autorotation procedures and performance data, ACS standards for Task CH.VIII.B.

2. Complete aircraft preflight inspection per POH checklist, verifying airworthiness documents, aircraft configuration, fuel quantity, and weight and balance within limits.

3. Participate actively in preflight briefing by asking clarifying questions about energy management, environmental effects, and risk management items. Demonstrate understanding by explaining back key concepts when prompted by the instructor.

4. Calculate current density altitude using field elevation, temperature, and altimeter setting. Compare to POH performance charts and brief expected descent rate and flare performance.

5. Complete pre-maneuver checklist items:

   • Verify simulated emergency checklist accessible
   • Identify suitable landing area (clear of obstacles, into wind, defined touchdown point)
   • Conduct two 90-degree clearing turns
   • Make radio call: “[Location] traffic, [Callsign] practicing autorotations [location], [altitude]”
   • Brief entry altitude, entry airspeed, target rotor RPM range, recovery altitude, and go-around criteria

6. Execute straight-in autorotation procedure as demonstrated:

   • Position helicopter on downwind, 500-700 feet AGL, aligned with landing area
   • At entry point (abeam touchdown point), smoothly roll throttle to flight idle while simultaneously lowering collective to maintain rotor RPM and applying right pedal to maintain heading
   • Establish and maintain autorotation airspeed ±5 knots
   • Monitor rotor RPM continuously—maintain within green arc using small collective adjustments
   • Compensate for wind drift using cyclic to track toward the intended touchdown point
   • Initiate deceleration and flare at appropriate altitude (50-100 feet AGL)
   • Apply power smoothly at recovery altitude (typically 10-20 feet AGL or as briefed)
   • Terminate to a stabilized hover within 100 feet of designated touchdown point

7. Maintain continuous situational awareness by cross-checking:

   • Rotor RPM (primary instrument scan item)
   • Airspeed indicator (target ±5 knots)
   • Altitude AGL (knowing position in descent profile)
   • Landing area alignment and drift correction needed
   • Obstacle clearance
   • Engine instruments during power recovery phase

8. Verbalize abnormalities or unsafe conditions immediately:

   • “Rotor RPM is decaying, lowering collective and nose”
   • “Descent rate is excessive, I need power now”
   • “I’m going to overshoot the landing area, adding power”
   • “Vehicle entering the landing area, executing go-around”

9. Respond to instructor coaching by making prompt corrections:

   • If rotor RPM is out of limits: adjust collective and/or pitch attitude immediately
   • If airspeed deviates: adjust pitch attitude to correct
   • If drifting off course: apply cyclic correction into the wind
   • If flare timing is incorrect: adjust flare initiation point on next attempt

10. Demonstrate task prioritization when distractions occur:

    • Maintain rotor RPM first (survival priority)
    • Maintain airspeed second (energy management)
    • Navigate toward landing area third (situation permitting)
    • If task saturation occurs, announce intention to execute power recovery

11. Perform self-critique after each iteration:

    • “My rotor RPM was good until the flare—I raised collective too aggressively and it decayed into the yellow. Next time I’ll raise collective more gradually.”
    • “I started the flare at 75 feet, which was too low. I barely arrested the descent. Next time I’ll start at 100 feet.”
    • “I landed 200 feet past the intended point because I didn’t correct for the tailwind component. Next time I’ll steepen my approach angle.”

12. Ask questions when procedures or techniques are unclear:

    • “In high-density altitude, should I increase my autorotation airspeed or keep it at the POH value?”
    • “If I start to overshoot the landing area, is it better to steepen the approach or add power and go around?”
    • “How do I judge the correct flare initiation altitude when conditions change?”

13. Practice decision-making during scenario-based questions:

    • When asked, “What would you do if rotor RPM decayed below limits at 200 feet AGL?” respond with: “Immediate corrective action: lower collective fully, lower the nose to increase airflow through the rotor. If RPM does not recover within 2-3 seconds, execute power recovery immediately. Altitude is still sufficient for recovery.”

14. Demonstrate risk management by identifying hazards before and during the maneuver:

    • “Wind is from 280 at 12 knots, so I’ll need continuous left drift correction during descent.”
    • “Density altitude is 5,500 feet today, so I expect higher descent rate and reduced flare effectiveness. I’ll enter at 700 feet instead of 500 feet.”
    • “There’s a vehicle near the south end of the runway. I’ll select a touchdown point well north of that position.”

15. Complete post-flight procedures:

    • Conduct normal landing, taxi, and shutdown per checklist
    • Secure aircraft per POH
    • Participate in post-flight debrief, acknowledging areas of strong performance and areas needing improvement
    • Document lesson in personal training records
    • Review errors and plan specific improvements for next lesson

Completion Standards

The lesson is complete when the student consistently demonstrates the ability to execute a straight-in autorotation to power recovery meeting the commercial pilot ACS standards for Task CH.VIII.B. Specifically, the student must:

1. Complete the appropriate checklist(s) including pre-maneuver checklist, simulated emergency checklist (accessible and reviewed), and post-recovery checklist. Checklist usage must be timely and not interfere with aircraft control.

2. Make radio calls as appropriate including pre-maneuver position and altitude call to announce autorotation practice, and post-recovery call if remaining in the practice area. Radio calls must use standard phraseology and include aircraft identification, location, altitude, and intentions.

3. Select a suitable landing area that is:

   • Clear of obstacles (wires, towers, buildings, vehicles, persons)
   • Oriented into the wind to the maximum extent possible
   • Of sufficient size to provide margin for lateral drift or overshoot
   • Has a clearly defined touchdown point for precision landing evaluation

4. Clear the area by completing a minimum of two 90-degree clearing turns, visually scanning for conflicting traffic, and verifying the approach path and landing area are clear of obstacles and hazards.

5. Select an appropriate entry altitude that provides sufficient altitude for the complete maneuver with safety margin. Minimum entry altitude is per POH/RFM or 500 feet AGL, whichever is higher. Entry altitude should be increased when:

   • Density altitude is high
   • Gross weight is high
   • Student proficiency is developing
   • Turbulence or windshear is present

6. Initiate the maneuver at the proper point such that the descent profile will result in arriving at the intended touchdown point. Entry point is typically abeam the touchdown point on a downwind leg at pattern altitude. Student must demonstrate judgment in positioning based on wind conditions (headwind requires closer entry point, tailwind requires more distant entry point).

7. Establish power-off glide with the helicopter trimmed and autorotation airspeed, ±5 knots. Upon simulated engine failure:

   • Collective is lowered smoothly and fully to maintain rotor RPM
   • Right pedal is applied to maintain heading
   • Pitch attitude is adjusted to achieve autorotation airspeed per POH/RFM (typically 60-70 KIAS depending on helicopter model)
   • Airspeed is maintained within ±5 knots throughout the descent (ACS standard)
   • Collective is trimmed full down to reduce control pressures

8. Maintain main rotor (Nr) within normal limits throughout all phases of the maneuver:

   • During entry: rotor RPM remains in green arc (no excursion into yellow or red)
   • During descent: rotor RPM is actively managed to remain in green arc using small collective and pitch attitude adjustments
   • During flare: rotor RPM is allowed to increase as airspeed decreases, but does not exceed redline
   • During power recovery: rotor RPM is maintained in green arc by coordinating collective application with power increase
   • Student must demonstrate immediate corrective action if rotor RPM trends toward limits

9. Compensate for wind speed and direction as necessary to avoid undershooting or overshooting the selected landing area. Student must:

   • Analyze wind direction and velocity during preflight planning
   • Apply cyclic inputs during descent to maintain ground track toward touchdown point
   • Adjust descent profile (steeper or shallower) as needed to arrive at the intended point
   • Demonstrate awareness of wind gradient effects during final descent and flare

10. Use proper deceleration and collective pitch application that permits safe clearance between the aircraft tail boom and the surface. During the flare and recovery:

    • Flare is initiated at an altitude that allows complete energy management without tail boom strike risk
    • Aft cyclic is applied progressively and smoothly to decelerate the helicopter
    • The helicopter transitions from nose-low to level or slightly nose-high attitude
    • Collective application during power recovery is coordinated with pitch attitude to maintain tail boom clearance
    • At no time does the tail boom approach within 2 feet of the surface (safety margin)

11. Initiate proper power recovery by:

    • Rolling throttle from flight idle to flight position smoothly (typically 1-2 seconds)
    • Coordinating collective increase with power application to prevent rotor RPM decay
    • Applying left pedal as needed to compensate for increasing torque
    • Monitoring engine instruments (RPM, torque, temperatures) for normal indications
    • Avoiding overtorquing or over-temping the engine during power application
    • Establishing positive rate of climb or arresting descent as appropriate for altitude

12. Terminate autorotation to a stabilized hover, within 100 feet of a designated point (ACS standard for commercial):

    • Hover is established at 3-5 feet AGL (or POH-recommended hover altitude)
    • Lateral position is within 100 feet of the pre-designated touchdown point
    • The helicopter is stable in all axes (no oscillations, drifting, or altitude deviations)
    • Heading is within ±10 degrees of the intended heading (into the wind)
    • All engine parameters are normal and aircraft is in controlled flight

Additional Completion Standards

• Risk Management: Student identifies and mitigates all ACS risk management items during the preflight briefing and demonstrates risk awareness during execution (e.g., monitoring for low rotor RPM, maintaining situational awareness, recognizing energy state deterioration, executing go-around when appropriate).

• Consistency: Student executes a minimum of three consecutive autorotations meeting all ACS standards above without instructor intervention.

• Decision-Making: Student demonstrates appropriate aeronautical decision-making by:

  • Recognizing when a go-around is necessary (unstable approach, rotor RPM out of limits, excessive drift, obstacle conflict)
  • Executing immediate corrective action when parameters deviate from acceptable ranges
  • Communicating intentions clearly and maintaining situational awareness under task-loading conditions

• Knowledge: During oral questioning (preflight or post-flight), student accurately explains:

  • Effects of wind, weight, temperature, and density altitude on autorotation performance
  • Energy management principles and trade-offs between altitude, airspeed, and rotor RPM
  • Causes and effects of high descent rates
  • Rotor RPM management techniques and hazards of low/high rotor RPM
  • Risk management items from ACS Task CH.VIII.B

Grading: Student performance will be evaluated as:

• Satisfactory: Meets all completion standards above on at least three consecutive iterations with minimal instructor coaching
• Unsatisfactory: Fails to meet one or more completion standards, requires significant instructor intervention to maintain safety, or demonstrates insufficient understanding of knowledge or risk management items

Remedial Training: If completion standards are not met, instructor will identify specific deficiencies, provide additional demonstration and practice as needed, and schedule continuation training focused on problem areas.

ACS Reference: All completion standards above are derived from FAA-S-ACS-16, Area of Operation VIII (Emergency Procedures), Task B (Straight-In Autorotation in a Single-Engine Helicopter), ACS Code CH.VIII.B.