Spins on the Hoist Hook – Causes, Avoidance, and Response
Spins on the hoist hook are predictable—and preventable—once you understand the airflow you’re operating in.
Loads start to spin beneath the aircraft primarily due to rotor wash interacting with the surface area of the load. In most cases, spins develop as the load passes through the turbulent flight zone (TFZ)—the region beneath the aircraft where induced flow has the largest effect on a hoist load.
The TFZ is typically most concentrated about one rotor diameter below the aircraft. The strength and shape of the rotor downwash depend on aircraft type, weight, rotor system, and environmental conditions.
More lift equals more induced flow. Larger rotor systems and different fuselage shapes distribute that flow differently, but the operational takeaway is consistent: in no or low wind conditions, there is a region beneath the aircraft where rotor wash will significantly affect the load.
Prevention starts with keeping the load out of that zone—or minimizing the time spent in it.
If feasible, a trail line or tag line can provide horizontal stability and reduce the likelihood of spins. These are most effective when the line maintains a shallow angle (roughly 0–60° from horizontal). As the line approaches vertical, its ability to control rotation is minimal.
Wind or forward airspeed helps by deflecting induced flow aft, flattening the TFZ and reducing its effect on the load. Terrain and obstacles can have the opposite effect—funneling and accelerating rotor wash, increasing the likelihood of instability.
Trail lines, hoist altitude, expected aircraft response, and contingencies should all be briefed prior to the evolution. The key is prevention.
When a spin develops, the priority is straightforward: get the load out of the TFZ.
If conditions and obstacles allow:
• Clear the load of all obstacles.
• Establish 20–30 knots of forward airspeed.
Forward airspeed moves the rotor wash aft and removes the load from the most turbulent flow. This is often the fastest and most reliable way to stop a spin.
If forward flight is not immediately available:
• Pay out cable to move the load lower and out of the TFZ (or return it to the surface if required).
• Hoist riders can attempt to counter rotation using body position or airflow (“grabbing air”), though effectiveness may be limited once a spin is established
If a trail line is in use, maintain awareness of entanglement risk during any lateral movement.
SR3 Rescue Concepts, a civilian hoist training company, partnered with the Real ResQ podcast to produce a free webinar that expands on these concepts. It’s a strong reference for the hoisting community:
SR3 Rescue Concepts Hoist Spin Webinar
Note – SR3 teaches a no-tagline departure profile where the load is lifted just clear of the surface, held low (below the TFZ), then the aircraft transitions to forward flight before recovery. This technique has a time and place. In low or no-visual cue environments (IMC or offshore dark night), this effectively becomes an instrument procedure and is not advisable. In tight or confined areas, maintaining precise lateral position during a climbing hover can also degrade obstacle clearance.
As with any advanced technique, it must be applied deliberately and only when conditions support it.
That said, the underlying concept is broadly applicable: maximize the distance between the load and the rotor wash until the flow flattens.
The key point is this:
Spins are solved by changing the airflow.
Understanding where the TFZ exists—and how to minimize it and minimize load exposure to it—reduces the likelihood of a manageable problem becoming a dangerous one.