Slope Operations

Objective

Upon completion of this lesson, the student will demonstrate the ability to safely perform slope operations in accordance with FAA-S-ACS-15 PH.IV.E. The student will identify suitable slope landing areas, execute parallel slope landings and takeoffs within manufacturer limitations, and apply appropriate risk management techniques for slope operations.

Content

Regulatory Foundation

Slope operations are conducted under 14 CFR 91.119 minimum safe altitudes and 14 CFR 61.87(n) for solo student operations. While not explicitly regulated, slope operations require adherence to manufacturer limitations per 14 CFR 91.9 and proper aeronautical decision-making per 14 CFR 91.3.

Aerodynamics of Slope Operations

When operating on slopes, the helicopter’s dynamics change significantly due to the uneven ground reference. The upslope main rotor blade travels through less dense air (due to reduced ground effect) while the downslope blade operates in enhanced ground effect. This creates an asymmetric lift condition that must be managed through cyclic control.

Think of ground effect like a cushion of air beneath the helicopter. On level ground, this cushion is even. On a slope, it’s like sitting on a tilted cushion - one side has more support than the other.

Slope Landing Techniques

Parallel Slope Approach: The helicopter approaches the slope at a shallow angle, maintaining the nose into the wind when possible. The approach is stabilized with a slight nose-low attitude to maintain visual contact with the intended landing spot.

Power Management: Slope landings require precise power control. Unlike level landings where power is reduced steadily, slope landings often require power adjustments to counteract the uneven ground effect and maintain desired approach angle.

Touchdown Sequence: Contact is made with the downslope skid first, followed by gentle settling onto the upslope skid. This prevents dynamic rollover and maintains lateral control throughout the landing sequence.

Slope Takeoff Techniques

Departure Profile: Takeoffs begin by lifting the upslope skid first while maintaining lateral control with cyclic. The helicopter is then transitioned to a hover before beginning forward flight.

Critical Azimuth Awareness: The most hazardous condition occurs when the upslope skid lifts and the helicopter begins to pivot around the downslope skid. Immediate corrective action prevents dynamic rollover.

Dynamic Rollover Prevention

Dynamic rollover occurs when the helicopter pivots laterally around a skid or wheel, with increasing roll rate that can exceed the pilot’s ability to recover. On slopes, the critical angle for rollover initiation is reduced due to the ground angle.

Contributing Factors:

• Excessive lateral cyclic input
• High power settings during ground contact
• Crosswind conditions
• Soft or uneven surfaces
• Pilot overcontrol or delayed reactions

Prevention: Smooth, deliberate control inputs, immediate recognition of lateral movement, and proper power management eliminate rollover conditions.

Risk Management for Slope Operations

Manufacturer Limitations Compliance: Per ACS risk management requirements, parallel slope operations must comply with manufacturer limitations. For helicopters without published slope limitations, demonstrations are limited to approximately 5-10 degrees maximum slope angle.

Prohibited Operations: Landings with the helicopter facing uphill or downhill are prohibited during certification testing due to extreme rollover risk and limited escape options.

Area Survey Requirements: A thorough review of the slope operations area is mandatory to ensure adequate clearance from obstacles, wires, terrain features, and other hazards. This includes identifying escape routes and alternate landing areas.

Environmental Considerations: Wind direction relative to slope angle affects controllability. Crosswinds can complicate lateral control during touchdown and liftoff phases. Surface conditions (loose rocks, soft soil, vegetation) impact skid grip and rollover potential.

Decision Points: Establish clear go/no-go criteria including maximum slope angles, wind limitations, surface conditions, and pilot proficiency levels.

Schedule

Equipment

Required References:

• FAA-S-ACS-15 Private Pilot Helicopter Airman Certification Standards
• FAA-H-8083-21B Helicopter Flying Handbook Chapter 11
• Helicopter Flight Manual/Pilot Operating Handbook
• Current sectional chart of practice area

Training Materials:

• Whiteboard for diagram sketches
• Model helicopter for demonstration
• Slope operations video (if available)
• Risk assessment checklist

Safety Equipment:

• First aid kit
• Fire extinguisher
• Emergency locator beacon
• Ground crew coordination equipment

Instructor Actions

1. Conduct comprehensive preflight briefing covering slope operation theory, risks, and emergency procedures
2. Demonstrate proper slope assessment techniques using visual references and slope measurement methods
3. Select appropriate practice slopes meeting ACS limitations (5-10 degrees maximum)
4. Perform complete area survey with student, identifying hazards and escape routes
5. Demonstrate parallel slope approach technique, emphasizing stabilized approach parameters
6. Execute demonstration slope landing, narrating power management and control inputs
7. Show proper ground handling procedures while on slope, including collective and cyclic positions
8. Demonstrate slope takeoff technique, emphasizing upslope skid lift sequence
9. Guide student through progressive slope operations, starting with shallow slopes
10. Provide immediate feedback on control inputs, approach angles, and risk management decisions
11. Monitor for dynamic rollover indications and provide corrective guidance
12. Debrief each approach and landing, highlighting successful techniques and areas for improvement

Student Actions

1. Participate actively in preflight briefing, asking questions about unclear concepts
2. Assist in slope assessment and area survey, identifying potential hazards
3. Observe instructor demonstrations while taking mental notes of techniques
4. Practice slope operations under instructor supervision, starting with gentle slopes
5. Maintain situational awareness throughout operations, monitoring for hazard development
6. Execute smooth control inputs to prevent dynamic rollover initiation
7. Demonstrate proper decision-making regarding go/no-go determinations
8. Apply risk management strategies appropriate to slope conditions
9. Communicate intentions and concerns clearly with instructor
10. Self-assess performance and identify areas requiring additional practice

Completion Standards

The student demonstrates satisfactory performance when they can:

Knowledge Requirements (FAA-S-ACS-15 PH.IV.E):

• Explain the aerodynamic principles affecting helicopters during slope operations
• Identify manufacturer limitations for slope operations or apply 5-10 degree limitation when none published
• Describe dynamic rollover causes, recognition, and prevention techniques
• List risk factors specific to slope operations and appropriate mitigation strategies

Risk Management (FAA-S-ACS-15 PH.IV.E):

• Conduct thorough area survey ensuring clearance from hazards before slope operations
• Operate within manufacturer limitations or 5-10 degree maximum when no limitations published
• Recognize and avoid conditions conducive to dynamic rollover
• Demonstrate proper go/no-go decision making for slope operations

Skill Requirements (FAA-S-ACS-15 PH.IV.E):

• Select suitable slope landing areas considering wind, obstacles, and surface conditions
• Execute stabilized parallel slope approaches maintaining directional control
• Perform slope landings with downslope skid contact first, smooth power control, and no dynamic rollover indications
• Complete slope takeoffs lifting upslope skid first while maintaining lateral control
• Maintain positive aircraft control throughout all phases of slope operations
• Demonstrate immediate recognition and correction of any lateral movement or rollover tendency