I bring you a weekly bite-sized chunk of the science behind helicopter human factors and CRM in practice, simplifying the complex and distilling a helicopter related study into a summary of less than 500 words.
TITLE:
Workload in helicopter rescue operations – A comparison of two different rescue methods in a randomised cross-over design.
WHAT?
A study comparing helicopter crews’ reported subjective workload and physiological workload (heart rate) data during hoisting and static rope rescue methods during Helicopter Emergency Medical Services (HEMS) flights.
WHERE?
Norway HEMS, in flight (BK117D3 helicopter) at 56 different rescue sites.
WHEN?
Published 2025. Field data collection over three 2024 seasonal periods (winter, summer, autumn).
WHY?
Rope rescue operations are standard in Norwegian HEMS, but may impose high workload and safety risks for crews. The organisation is considering adding a hoisting capability, and needed objective evidence on workload and operational safety to inform this strategic decision.
HOW?
11 HEMS crew members (4 pilots, 3 physicians, 4 rescuers) performed 55 standardised rescue training missions. Each was executed twice, once using rope rescue techniques and once using a hoist. Workload was measured using both the NASA-TLX subjective scale where crews report perceived workload, and physiological markers of heart rate (HR) and heart rate variability using Polar wrist-worn sensors.
FINDINGS:
- Across all roles and phases crew reported lower subjective workload during hoist operations than during rope operations.
- Of the crew members, the pilots experienced the largest reduction in workload, likely reflecting fewer control inputs, reduced need for height adjustments, and more stable visual references.
- Hoist/Rope operators and rescuers also reported lower workload during hoisting.
- The physiological data aligned with reported workload for pilots, with hoist operations showing a significantly reduced heart rate.
- Hoist operators showed increased HR during hoist phases than rope phases despite reporting lower subjective workload, possibly due to increased physical effort rather than mental strain.
- Heart rate metrics were significantly correlated with reported subjective scores for all three roles.
- Overall, hoist operations appeared to reduce workload and potentially enhance flight safety, particularly by reducing pilot cognitive load. .
SO WHAT?
This study demonstrates that physiological monitoring coupled with subjective workload tools provide a feasible way to quantify workload in helicopter crews during live or simulated missions. The correlations between heart-rate-based physiological measurements and subjective workload suggest that reliable physiological workload data can be obtained while crews are airborne, without interfering with mission duties.
The study also demonstrates the value of simple, lightweight wearable sensors (in this case a Polar H10 wrist unit) for capturing real-time workload in demanding helicopter operations. This low-cost, non-intrusive tool is easy to integrate into routine missions and could enable multi-crew, multi-role workload profiling in real operations.
This study makes the case for further in-the-field research to facilitate evidence-based decision-making for operators about future aircraft and equipment capability choices (as seen here with hoist vs rope).
REFERENCE:
Mattingsdal, H., Dahle, T. N., Abrahamsen, E. B., Søvik, S., & Ottestad, W. (2025). Workload in helicopter rescue operations – A comparison of two different rescue methods in a randomized cross-over design. Safety Science, 192, 106996.
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