Operational Procedures — PPL(H)

Helicopter-specific VFR procedures, emergency actions, autorotation, vortex ring state, and the regulatory framework for UK rotary operations.

Exam Focus

Most Relevant To

  • Operational Procedures
  • Air Law
  • Principles of Flight

Know This Cold

  • Autorotation: the procedure for engine failure in a helicopter — entry, glide, flare, cushion.
  • Vortex ring state: how it forms, how to recognise it, and the only recovery action.
  • LTE (Loss of Tail Rotor Effectiveness): conditions and avoidance.
  • Dynamic rollover: cause, recognition, and prevention.
  • Emergency transponder codes: 7700, 7600, 7500.
  • SARTIME requirements.

Autorotation — Engine Failure Procedure

When the engine fails in a helicopter, the freewheeling unit automatically disconnects the transmission from the engine. The rotor continues to spin using energy stored in the blades and the airflow through the disc during descent. This is autorotation — the helicopter glides in a controlled descent.

  • Entry: lower collective immediately to reduce RRPM decay. Establish autorotative glide speed (typically 60–65 KIAS on R22/R44).
  • Glide: maintain target RRPM and airspeed. RRPM in the green arc is the priority.
  • Flare: at approximately 40–50 ft, apply aft cyclic to slow forward speed and exchange kinetic energy for reduced rate of descent.
  • Cushion: as flare completes and aircraft is level, raise collective to absorb remaining descent — RRPM decreases rapidly at this point.

Common Mistake

Not lowering collective immediately on engine failure is the most common autorotation error. Delay causes RRPM decay — once RRPM is too low, it cannot be recovered and the helicopter will not flare or cushion effectively. Entry must be immediate.

Vortex Ring State

Vortex ring state occurs when the helicopter descends into its own downwash. The rotor is working at low power, the aircraft is descending nearly vertically, and the vortices generated at the blade tips recirculate through the disc, reducing lift dramatically and increasing the descent rate further. It can be catastrophic at low altitude.

  • Conditions: low airspeed (below 20 kt), high rate of descent (above 300–500 fpm), low power (collective partially or fully lowered).
  • Recognition: increasing vibration, buffeting, loss of normal collective effectiveness — the collective no longer increases lift.
  • Recovery: only way is to break the recirculation. Apply forward cyclic to increase airspeed — this is the only reliable recovery in a fully developed state.
  • Raising collective in vortex ring state makes it worse — more power drives more recirculation.

Instructor Tip

The most dangerous time for vortex ring state: steep confined area approach, downwind approach with a tailwind increasing the effective descent rate, or hovering in a strong updraft then flying out of it. Always maintain some forward speed during descent.

Loss of Tail Rotor Effectiveness (LTE)

LTE is a condition where the tail rotor cannot produce sufficient thrust to maintain directional control, causing the helicopter to rotate rapidly. It can occur in a variety of wind conditions.

  • Most common: hovering or flying slowly downwind, especially with a crosswind from the left rear.
  • Vortex ring on tail rotor: similar to main rotor vortex ring — occurs in certain wind/power combinations.
  • Wind from left rear (weathercock instability): main rotor wash impinges on tail rotor, reducing effectiveness.
  • Recovery: lower collective to reduce torque demand, increase airspeed — land as soon as possible.

Dynamic Rollover

Dynamic rollover occurs during take-off or landing when one skid is on the ground (or snagged) and the other rises, rolling the helicopter about the ground contact point. Once the roll rate exceeds the cyclic authority, the helicopter cannot be recovered.

  • Most common: landing/taking off on sloping ground, skid catching on an obstacle, or lateral cyclic input while one skid is on the ground.
  • Prevention: never lift one skid with lateral cyclic while the other is on the ground.
  • Recovery: lower collective immediately if roll is detected early — do not apply lateral cyclic against the roll, as this can delay recognition.

Engine Failure at Altitude — Procedure

Step 1

Lower collective immediately — prevent RRPM decay.

Step 2

Establish autorotative airspeed (~60 kts R22/R44).

Step 3

Select a landing area — fields, roads, flat ground.

Step 4

Flare at 40–50 ft, cushion landing, lower collective as aircraft stops.