Preparing for Recovery in Heavy Seas and Surf- Aircraft Orientation and the Green Zone
Aircraft orientation refers to the helicopter’s position relative to incoming waves during swimmer deployments and recoveries. The following orientations assume the right seat pilot is flying, and the flight mechanic (hoist operator) is hoisting and providing positioning guidance for placing the aircraft in relation to the rescue swimmer (RS) and survivor from the right cabin door.
For simplicity, four helicopter orientations (each 90-degrees) are presented. Each helicopter orientation has what we refer to as a “green zone.” The “green zone” is the area where the crew will be most successful in maintaining the “chain of energy” (wave energy → RS/survivor → hoist drum) while preparing to recover the swimmer and survivor. Because, in many helicopters, wind direction dictates the necessary orientation due to power margins and tail rotor effectiveness/directional control, understanding the concept of the green zone in each of the four orientations allows operators to create a mental model of the green zone regardless of orientation (360 degrees).
In general, “door to” and “nose to” helicopter orientations to wave energy are most advantageous. “Tail to” is more challenging and “door away” is the most difficult with the smallest margin for error. As such, if aircraft performance permits, using a “door to” or “nose to” orientation that is not in the wind line improves crew performance and safety margins by allowing the crew to maintain the appropriate chain of energy (wave energy → RS/survivor → hoist drum) due to better visibility of the RS and incoming waves.
Orientation descriptions:
Image credit – U.S. Coast Guard’s Advanced Helicopter Rescue School
In the Door to Wave orientation, the aircraft is positioned with the survivor and incoming waves at the 3 o’clock position. The RS is deployed, and the aircraft drifts left in surf to match the RS/survivor’s movement in the wave action. Keeping the RS and survivor near the 3 o’clock position provides the lowest chance of cable snag on the aircraft and offers excellent visibility of the waves for the pilot flying (PF), flight mechanic (FM), and RS.
Image credit – U.S. Coast Guard’s Advanced Helicopter Rescue School
In the Nose to Wave orientation, the aircraft is positioned with the waves and the survivor at the 1 to 2 o’clock position. After deployment, the aircraft moves aft in surf to maintain a consistent distance from the RS/survivor. This setup gives the PF a clear view of the incoming waves and the RS/survivor, and is commonly used since wind-driven waves are typically aligned with the wind line. In this orientation, the risk of cable snag is higher because the cable is closer to landing gear and other obstacles near the nose of the aircraft.
Image credit – U.S. Coast Guard’s Advanced Helicopter Rescue School
In the Tail to Wave orientation, the aircraft is oriented with the survivor at the 4 to 5 o’clock position, but the aircraft moves forward during the evolution. This technique allows the waves to push the RS and survivor toward the hoist, which helps with positioning, but makes it more challenging for the PF to maintain visual contact with the survivor. In this configuration, the FM must call out incoming waves, and the PF must rely heavily on those advisories, as well as conning commands or visual references forward of the aircraft.
Image credit – U.S. Coast Guard’s Advanced Helicopter Rescue School
Lastly, in the Door Away from Wave orientation, the aircraft is positioned directly above the RS and survivor, with the aircraft drifting right after deployment. The RS and survivor are kept near plumb, and the aircraft moves laterally to match their drift. This configuration has increased risk of cable shockloads, reduced visibility of wave sets for all crew members, and an earlier loss of visual contact with the RS/survivor during recovery. The FM must maintain sufficient cable slack to accommodate wave action, and the pilot monitoring (PM) should call out wave hazards to support the PF.
