Electrostatic Discharge During Helicopter Hoist Operations: A Nationwide Prospective Study of the Norwegian Search and Rescue Service.

Objectives: In helicopter search and rescue (SAR), rescue hoists or static underslung lines are frequently used for patient access. Electrostatic charges accumulated by the aircraft can discharge through hoisted health care personnel, a phenomenon known as electrostatic discharge (ESD) or "static." These discharges can potentially cause serious injury, yet there is a surprising scarcity of published data on their incidence and clinical impact. We aimed to determine the incidence and severity of ESD during hoist operations within the Norwegian SAR service. Methods: We conducted a nationwide, 1-year prospective observational study including all SAR bases operated by the 330 Squadron in Norway, between February 1, 2025, and January 31, 2026. All SAR hoist missions and training exercises conducted over the 1-year period were included. Data collected included ESD occurrence, hoist mission characteristics, atmospheric conditions, and subjective/objective severity of the discharge. Results: Of the 839 hoist operations performed during the study period, ESD occurred in 28 of these, representing an overall incidence of 3.3%. The risk of ESD was significantly higher during hoists over water compared with land (odds ratio [OR] 2.18, 95% CI 1.01-4.70). There was precipitation within 5 nautical miles in 71% of ESD incidents, and grounding equipment was found inadequate in 64%. Severity was classified as moderate in 29% (n = 8) and severe in 21% (n = 6) of ESD incidents. Two rescue paramedics required hospital admission. ESD caused communication equipment failure in 11% (n = 3) of incidents and led to the termination of the hoist operation in 18% (n = 5) of the incidents. Conclusion: This nationwide study demonstrates that ESD occurs in 3.3% of hoist operations performed by the SAR service in Norway. With half of the ESD incidents rated as moderate or severe and a notable frequency of mission terminations and hospitalizations, ESD represents a significant occupational hazard. These findings highlight an urgent need to re-evaluate safety protocols for SAR personnel, and to further investigate the scope and health implications of ESD for SAR personnel.