Normal and Crosswind Approach

Objective

The student will demonstrate knowledge of normal and crosswind approach procedures and perform normal and crosswind approaches to a safe landing or hover within ACS standards. Upon completion of this lesson, the student will be able to:

1. Explain the effects of wind, weight, altitude, and temperature on helicopter approach performance (Knowledge - FAA-S-ACS-15 PH.V.B)
2. Demonstrate proper wind correction techniques during approach and landing (Knowledge/Skill - FAA-S-ACS-15 PH.V.B)
3. Select appropriate landing surfaces and touchdown points considering obstructions and hazards (Knowledge/Skill - FAA-S-ACS-15 PH.V.B)
4. Explain factors affecting the height/velocity diagram profile during approaches (Knowledge - FAA-S-ACS-15 PH.V.B)
5. Execute normal and crosswind approaches maintaining airspeed ±10 knots, arriving at termination point ±4 feet (Skill - FAA-S-ACS-15 PH.V.B)
6. Identify and mitigate risks associated with various wind conditions, surface conditions, and approach hazards (Risk Management - FAA-S-ACS-15 PH.V.B)

Content

Wind Effects on Approach Performance

Effects of Wind, Weight, Altitude, and Temperature:

• Headwind increases effective translational lift (ETL), allowing steeper approach angles with same power settings
• Tailwind reduces ETL effectiveness, requiring shallower approaches and increased power
• Crosswind creates asymmetric lift on the rotor disc, requiring cyclic correction and anti-torque adjustment
• Higher density altitude (high altitude/temperature, low pressure) reduces available power and rotor efficiency
• Increased gross weight requires higher power settings and affects autorotational glide distance
• Temperature affects power available - hot days reduce engine and rotor performance significantly

Wind Correction Techniques:

• Establish wind correction angle early in approach to maintain ground track
• Use crab method: point helicopter nose into wind to maintain desired ground track
• Transition to sideslip method before touchdown: lower upwind skid first, maintain longitudinal alignment with landing direction
• Monitor drift continuously - small corrections are more effective than large late corrections
• In gusty conditions, carry extra airspeed (5-10 knots) for control responsiveness

Landing Surface Selection and Touchdown Points

Landing Surface Considerations (14 CFR 91.119):

• Firm, level surface free of loose debris that could be blown up by rotor wash
• Adequate size for safe approach and departure considering helicopter dimensions
• Clear of obstacles in approach and departure paths
• Consider surface material: concrete/asphalt ideal, grass acceptable if firm, avoid soft dirt or sand
• Evaluate slope - maximum safe slope varies by helicopter type (typically 5-15 degrees)

Touchdown Point Selection:

• Choose point allowing normal approach angle (typically 6-10 degrees)
• Ensure adequate clearance from obstacles in approach path
• Consider go-around options - clear departure paths available
• Account for wind direction relative to obstacles and surface conditions

Height/Velocity Diagram Factors

The H/V diagram (dead man’s curve) represents combinations of height and airspeed to avoid during normal operations:

Factors Affecting H/V Profile:

• Gross weight: heavier aircraft has larger avoid area due to higher sink rates in autorotation
• Density altitude: reduces autorotational glide performance, expanding avoid area
• Center of gravity: aft CG reduces autorotational flare capability
• Aircraft configuration: external loads or equipment affect autorotational characteristics
• During approaches, minimize time spent in avoid area by maintaining appropriate airspeed for height

Risk Management

Wind-Related Risks:

• Crosswind: Causes drift, requires constant correction, affects LTE susceptibility at low speeds
• Windshear: Sudden wind changes can cause rapid altitude or airspeed variations requiring immediate pilot response
• Tailwind: Reduces ETL effectiveness, increases groundspeed, complicates distance judgment
• Turbulence/Wake Turbulence: Can cause uncommanded attitude changes, loss of control authority; avoid approaches behind large aircraft

Vortex Ring State (VRS) Prevention:

• Occurs with high rates of descent (>300 fpm) at low forward airspeeds (<30 knots)
• Avoid by maintaining forward airspeed throughout approach
• If encountered: lower collective, apply forward cyclic, increase airspeed before attempting recovery

Surface and Approach Path Risks:

• Touchdown Surface: Evaluate firmness, slope, contamination; soft surfaces can cause dynamic rollover
• Obstructions: Power lines, towers, trees in approach path; maintain safe clearance margins
• Go-around Planning: Always have escape route planned; brief go-around procedures before approach

Operational Risks:

• Loss of Tail Rotor Effectiveness (LTE): Critical azimuth awareness (210-330 degrees), weathercock stability regions
• Collision Hazards: Other aircraft, ground vehicles, personnel in landing area
• Distractions: Maintain scan pattern, prioritize flight path control over secondary tasks
• Loss of Situational Awareness: Brief approach plan, maintain orientation with visual references

Schedule

Equipment

Required References:

• FAA-H-8083-21B Rotorcraft Flying Handbook Chapter 8
• FAA-S-ACS-15 Private Pilot Helicopter ACS Area V Task B
• Aircraft Pilot’s Operating Handbook/Flight Manual
• Sectional chart for local area
• 14 CFR Part 91 regulations

Materials:

• Helicopter model for wind effect demonstrations
• Wind correction angle calculator or E6B
• Approach angle demonstration aid
• H/V diagram for aircraft type
• Local area hazard map showing approach considerations

Visual Aids:

• Height/velocity diagram poster
• Wind triangle diagram
• LTE critical azimuth diagram
• Crosswind approach technique illustrations

Instructor Actions

1. Preflight Briefing: Explain lesson objectives, review current wind conditions using AWOS/ATIS, brief approach procedures and emergency actions
2. Demonstrate Wind Effects: Use helicopter model to show crosswind effects on approach path, explain correction techniques
3. Brief H/V Considerations: Show aircraft-specific H/V diagram, explain how approach profile affects time in avoid area
4. Review Risk Factors: Discuss VRS, LTE, windshear recognition, go-around decision criteria
5. Demonstrate Normal Approach: Execute stabilized approach showing proper sight picture, control inputs, and wind corrections
6. Coach Crosswind Approach: Guide student through wind correction angle establishment and sideslip transition technique
7. Demonstrate Go-Around: Show proper go-around technique from various points in approach
8. Monitor Student Performance: Observe control smoothness, wind correction effectiveness, altitude/airspeed control
9. Provide Corrective Feedback: Address common errors like excessive control inputs, poor wind drift correction, unstabilized approaches
10. Evaluate Decision Making: Assess student’s surface selection, hazard identification, and risk mitigation strategies

Student Actions

1. Preflight Planning: Determine wind conditions, calculate crosswind components, brief approach procedures
2. Radio Communications: Make appropriate traffic pattern calls, coordinate with tower if applicable
3. Wind Assessment: Determine wind direction using visual indicators (flags, smoke, water patterns)
4. Approach Execution: Establish normal approach angle, maintain airspeed within ±10 knots of target
5. Wind Correction: Apply appropriate crab angle to maintain ground track, transition to sideslip for landing
6. Hazard Scanning: Continuously scan approach path and landing area for traffic and obstacles
7. Performance Monitoring: Maintain rotor RPM and engine parameters within normal limits
8. Precision Flying: Arrive at termination point within ±4 feet horizontally
9. Go-Around Execution: Recognize unstabilized approach conditions and execute go-around when appropriate
10. Risk Assessment: Identify and communicate potential hazards throughout approach phase

Completion Standards

The student demonstrates satisfactory knowledge and skill in normal and crosswind approaches when they:

Knowledge Standards (FAA-S-ACS-15 PH.V.B):

• Explains how wind, weight, altitude, and temperature affect approach performance
• Describes proper wind correction techniques for approach and landing
• Identifies appropriate landing surfaces and touchdown points considering obstacles
• Explains factors affecting H/V diagram profile during approaches

Risk Management Standards (FAA-S-ACS-15 PH.V.B):

• Selects appropriate approach path based on wind conditions and aircraft limitations
• Identifies hazards associated with crosswind, windshear, tailwind, and turbulence
• Recognizes VRS conditions and demonstrates avoidance techniques
• Evaluates touchdown surface conditions and selects appropriate landing technique
• Demonstrates understanding of go-around procedures and decision criteria

Skill Standards (FAA-S-ACS-15 PH.V.B):

• Completes appropriate checklists for approach phase
• Makes proper radio calls for traffic pattern or approach procedures
• Determines wind direction using available indicators
• Aligns helicopter with correct runway or touchdown point
• Maintains effective scan for traffic and obstructions
• Establishes and maintains proper ground track with wind correction
• Maintains normal approach angle and rate of closure
• Keeps powerplant and main rotor RPM within normal operating limits
• Arrives at termination point (surface or stabilized hover) within ±4 feet
• Uses appropriate runway incursion avoidance procedures when applicable