Single-Engine Minimum Speed Landing Methods

Common Errors: 

• Excessive rate of descent requiring more power than is available to slow the helicopter’s descent. 
• High rate of closure resulting in excessive pitch attitude, risking bumper or stabilator contact with the ground. 
• “Stair-stepping” the approach requiring significant power fluctuations. 
• Approaching too shallow and coming up short. 
• Flying too slowly, resulting in power demands beyond capability. 

Teaching Techniques: 

• Invest power early to reduce inertia that must be overcome near the ground where power margins are tight. 
• With power bridged (near maximum available), adjust airspeed to control rate of descent. If descent increases, apply forward cyclic to increase airflow through the rotor system and reduce descent rate.
• When pilots are not managing power well, they are too slow to recognize and react to increased and decreased rates of descent (wide brackets of too slow and too fast). 
• A proficient single engine minimum speed pilot anticipates rate of decent changes and makes almost imperceptible cyclic adjustments that are small, smooth, and timely to fly a consistent glide path at an appropriate closure rate and rate of descent with power bridged.  
• Ideally, the helicopter should gain ground effect efficiency as it loses translational lift. 
• Apply the HAATS 3-2-1 Rule for zero ground speed single engine landing: 
  • Prior to being committed to the landing (decision point) 
    • Consistent Approach Angle 
    • Descent Rate: 300 fpm or less, 
    • Groundspeed: 20 KIAS or less, 
    • Power Margin: 10% or more. 

Notes – Holding 75–95 KIAS until 200 feet was once the standard profile for single-engine practice landings based on the rationale that maintaining an autorotational profile would offer a safer margin in the event of a second engine failure. However, the relatively aggressive deceleration required at low altitude often made it difficult to achieve a stabilized approach. As a community, we’ve shifted toward initiating the transition at a  higher altitude, which is reasonable given that most engine malfunctions are isolated to one engine and will not manifest in the remaining engine. An exception to this is fuel-related issues—such as contamination or starvation—which may affect both engines. In those cases, remaining in an autorotational profile until 200 feet still makes sense. The nuance of a faster lower transition can be a beneficial additional skill to experienced pilots who demonstrate a consistently high level of proficiency at stable minimum-speed, single-engine practice landings. 

Training Scars: 

The most probable scenario for a single engine minimum speed landing is an engine fire.  This situation will likely require an efficient single engine minimum speed landing, which may preclude jettisoning fuel from the main tanks. However, in training, rather than turning and descending toward a suitable landing site while simultaneously executing the engine fire emergency procedure, we often remain at altitude executing the emergency procedure in the downwind, potentially furthering the distance from the suitable landing site. For other single engine emergencies, although we will likely have the time to jettison fuel from the mains, we rarely discuss this option, and instead, train as though we cannot adjust the helicopter’s weight.