IIMC Rules to Live by
The moments immediately following “lost visual cues” are critical. Here are some rules to live by to maintain helicopter control as you establish an instrument scan:
1. NEVER turn AND descend when you are establishing an instrument scan near water, terrain, or obstacles. Many situations require a turn (add power to keep the helicopter level – the steeper the turn, the more power is required to maintain altitude) and some even require a descent (keep the wings level and establish an appropriate rate of descent). Executing both maneuvers during an IIMC event while being low to water, terrain, or obstacles has forced skilled crews into an unrecoverable situation. Keep it simple as you establish an instrument scan. Initial IIMC (lost visual cues) instrument scans are sluggish and turning and descending while establishing a scan often causes unrecognized rapid rates of descent.
2. Minimize pitch changes during challenging transitions to an instrument scan. Rapid pitch changes can result in disorientation. Amid the disorientation, as a pilot’s attitude scan breaks down, increased airspeed above bucket or decreased airspeed below bucket results in rapid descents. If able, maintain pitch attitude/airspeed, and climb with collective. If you need to change pitch attitude while establishing an instrument scan, do so at a moderate rate minimizing change as much as possible.
3. Rate of descent with limited visual cues should not exceed your height above water (e.g., at 400’ AWL, rate of descent should never be greater than 400 fpm, 300’ never greater than 300 fpm, 200’ never greater than 200 fpm).
4. Silence during high crew workload events = task saturation = delay in taking appropriate action. Articulate what is happening and what you are doing accurately, boldly, concisely. “Lost visual cues. Inadvertent IMC. Wings are level. Piper is on the horizon. Ball is centered. Increasing power, we are climbing at 500 fpm, turning at a half standard rate turn to the left, to the west, to remain over water…”
5. No one is “along for the ride.” All crew members should harness the tools available to them. In our helicopter, the crew has a readout (on the CDU) that displays altitude readouts (on the MSN page) and by pressing one button twice, they can back up the pilots with RADAR and Barometric altitudes. Crew members, without an altitude readout (CDU), can scan outside to see if visual cues return while the pilots establish their instrument scans. A timely “UP, UP, UP,” from a crew member as the helicopter inadvertently descended and he or she became visual with the water has resulted in aggressive collective pulls that have kept multiple helicopters out of the water during an unintentional descent.
