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:
Electrostatic discharge during helicopter hoist operations: A nationwide prospective study of the Norwegian Search and Rescue Service.
WHAT?
Study investigating the frequency, severity and operational consequences of electrostatic discharge (ESD), commonly known as static, during helicopter rescue hoisting. ESD occurs when electrical charge accumulated by the helicopter discharges through personnel or equipment, potentially causing injury or disrupting rescue operations.
WHERE?
Norway, across six operational SAR bases and one training base operated by 330 Squadron, Royal Norwegian Air Force, flying Leonardo AW101 helicopters.
WHEN?
Study conducted between February 2025 and January 2026. Published in JACEP Open in 2026.
WHY?
Although helicopter static electricity is a recognised hazard, surprisingly little research has quantified how frequently personnel experience potentially harmful discharges or their consequences. The researchers sought to establish the scale of the problem and identify circumstances associated with increased risk.
HOW?
Researchers conducted a year-long prospective observational study covering 839 operational and training hoists. Following each hoist, rescue paramedics or physicians completed an electronic report recording any ESD occurrence, environmental conditions, discharge severity and operational consequences. Statistical analysis explored associations between ESD and operational or environmental factors.
FINDINGS:
ESD occurred during 28 of 839 hoists (3.3%), with significant consequences:
Severity: Eight incidents (29%) were classified as moderate and six (21%) as severe. Some incidents involved overlapping symptoms.
Injuries: Reported effects included powerful shocks, falls, temporary paralysis and unconsciousness. Two paramedics required medical examination or hospital admission.
Operational impact: Communication equipment failed in three incidents (11%), while five hoists (18%) were terminated.
Environment: ESD was more than twice as likely over water (4.9%) than land (2.3%). Precipitation was present within five nautical miles in 71% of incidents.
The static discharge line had already contacted the surface before ESD occurred in 64% of incidents, suggesting existing grounding arrangements do not reliably eliminate the hazard.
The authors identified maritime hoisting during precipitation and temperatures above 3°C as a particularly prominent combination of conditions.
SO WHAT?
Static discharge is often regarded as an unpleasant but routine occupational hazard. This study challenges that assumption, demonstrating that ESD can cause significant injury, compromise communications and terminate rescue operations.
For SAR operators, the implications extend beyond electrical protection. An unexpected discharge can incapacitate a rescuer, disrupt crew communications and introduce an immediate secondary emergency during an already demanding hoist.
The findings support reviewing grounding equipment, and incorporating environmental conditions (particularly precipitation) into pre-hoist risk assessments, to prepare crews for ESD-related contingencies.
REFERENCE:
Brede, J. R., Storli, A., von Tangen-Jordan, S. B., & Coucheron, L. (2026). Electrostatic discharge during helicopter hoist operations: A nationwide prospective study of the Norwegian search and rescue service. JACEP Open, 7, Article 100468. https://doi.org/10.1016/j.acepjo.2026.100468
