Helicopter Rescue at Very High Altitude: Recommendations of the International Commission for Mountain Emergency Medicine (ICAR MedCom) 2025

Abstract

McLaughlin, Kyle, Charley Shimanski, Ken Zafren, Ian Jackson, Gerold Biner, Maurizio Folini, Andreas Hermansky, Eric Ridington, Peter Hicks, Giacomo Strapazzon, Marika Falla, Alastair Hopper, Dave Weber, Ryan Jackson, and Hermann Brugger. Helicopter rescue at very high altitude: recommendations of the International Commission for Mountain Emergency Medicine (ICAR MedCom) 2025. High Alt Med Biol. 27:107–116, 2026.

Background:

Helicopter mountain rescue is highly effective. However, air rescue operations at very high altitude (VHA), above 3500 m, are inherently hazardous because of challenging topography, dynamic weather, and hypobaric hypoxic environment. Currently, no established international guidelines exist for helicopter rescues at VHA.

Methods:

We conducted a narrative review of existing literature, supplemented by expert opinions from helicopter pilots, physicians, and rescuers actively engaged in VHA rescues. These recommendations were approved by the International Commission of Alpine Rescue (ICAR) Medical Commission and endorsed by the ICAR Air Rescue Commission.

Discussion:

We identified 19 key factors to consider, including operational parameters, ground site management, pilot and rescuer safety protocols, and psychological factors to assist air rescue programs in developing pre-mission, mission, and post-mission plans for helicopter rescue missions at VHA.

Conclusions:

By implementing the recommendations outlined in this article, helicopter rescue teams operating at VHA can improve response capabilities and minimize risks.

Keywords

high-altitude accidents mountain rescue supplemental oxygen extreme altitude high-altitude medicine helicopter air rescue very high altitude helicopter rescue rapid ascent human external cargo

Introduction

High-altitude travel is increasing in popularity (Benavides, 2025; Gurung, 2025; Mcintyre, 2022). As visitation to high elevations increases so does the likelihood of injury or illness requiring rescue. In the Swiss Alps, high altitude rescues have increased 2.6% annually, with over 50% of rescues occurring above 4,000 m (Gasser, 2022). The Everest region sees more than 50,000 people annually, and during the busiest trekking season, there may be as many as 60 helicopter rescue flights per day (Timesofindia.com, 2025).

The first recorded helicopter mountain rescue occurred in 1956 for a cardiac arrest above 4,000 m on Mont Blanc (Wikipedia, 2025). The highest altitude landing (8,848 m) took place on Mount Everest in 2005 (Wikipedia, 2024). The highest short-haul rescue (7,800 m) occurred on Lhotse in Nepal in 2013 (Airbus, 2025). As organized rescue teams have expanded in high-altitude regions, the advantages of rescue helicopters have become increasingly apparent (Frankema et al., 2004; Hotvedt et al., 1996; Mair et al., 2013; McVey et al., 2010).

Helicopter rescues have inherent risks. The U.S. National Park Service found that 38% of rescuer deaths resulted from helicopter crashes. One-third of search and rescue helicopter accidents were linked to poor weather or visibility (Farabee, 1997; Shimanski, 2012). In Italy, helicopter operations contributed to 1% of mountain rescue accidents but accounted for 37% of rescuer fatalities (Milani et al., 2023). The complexities of high-altitude environments, such as wind, temperature, barometric pressure, and terrain, introduce challenges for pilots, rescuers, and helicopters (Shimanski, 2012).

Altitudes from 3,500 to 5,500 m are considered “very high altitude” (VHA). Altitudes above 5,500 m constitute “extreme altitude” (Roach and Hackett, 2016). For this article, we will refer to VHA as altitude above 3500 m. Hypobaric hypoxia at VHA impairs cognitive and physical performance (Falla et al., 2024a; Ferretti and Strapazzon, 2024; Vogele et al., 2021; Wilson et al., 2009) and with time can cause acute high-altitude illness (HAI), including acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE) (Burtscher et al., 2021; Wilson et al., 2009). Helicopter rescues at VHA often require immediate deployment and rapid ascent, placing rescuers and pilots at risk of decreased cognitive and physical performance and, with longer exposure, HAI.

Although some rescue programs have developed high-altitude rescue protocols, no standard international guidelines exist. Current protocols vary based on altitude, terrain, and regional political and economic factors (Supplementary Data).

This narrative review examines factors influencing helicopter rescues at VHA, integrating scientific evidence and expert opinion from high-altitude rescue personnel, pilots, and members of the International Commission for Alpine Rescue (ICAR) Air Rescue (AirCom) and Medical (MedCom) Commissions. Our goal is to enhance the effectiveness of VHA rescue operations, reduce risks for pilots and rescuers, optimize team performance, and improve patient care in this challenging environment.

Methods

A working group from ICAR MedCom, ICAR AirCom, and VHA helicopter rescue experts developed the study objectives and research questions. We searched PubMed using the terms “helicopter,” “altitude,” AND “rescue” and conducted a manual review of the articles, reference texts, and citations. We analyzed and considered relevant studies of helicopter rescues at VHA for quality and applicability. We reviewed aviation guidelines from the European Union Aviation Safety Agency (EASA), the U.S. Federal Aviation Agency (FAA), the Canadian Transportation Agency, and the Civil Aviation Authority of Nepal (CAAN). We also obtained expert input from active high-altitude helicopter rescue pilots and rescuers. We established recommendations by consensus. We presented the recommendations at the 2024 ICAR Congress. They were approved as an ICAR MedCom recommendation and were endorsed by the ICAR AirCom.

Discussion

The working group formulated 19 key factors to consider (Table 1) for helicopter rescue teams operating at VHA. We categorized these considerations into pre-mission, mission, and post-mission recommendations.

Table 1.

Recommendations for Helicopter Rescue at Very High Altitudes

	Pre-mission recommendations
Team dynamics	Cultivate a culture of trust, cohesion, and competency with the goal of enhanced safety. Implement Incident Command System and Crew Resource Management concepts to enhance response coordination, efficiency and safety.
Training	Rescuers should be familiar with high altitude gear and techniques, high-altitude illness, and cold injury. Refresher training with proximity flying and HEC above 3500 m on at least an annual basis is essential.
Acclimatization	Acclimatized pilots and rescuers with high altitude flying proficiency are preferred. Avoid deploying rescuers with a history of high altitude pulmonary edema.
Meteorological conditions	Evaluate and anticipate weather conditions, especially temperature and wind conditions.
Pre-flight risk	Use a high-altitude rescue analysis matrix (Table 1) to assess and mitigate risk.
Backup ground rescue plan	If unable to complete the helicopter mission, establish a ground rescue option from a designated staging area.
Contingency plan for aircraft grounding	Confirm egress plan for pilot and crew to descend safely by ground. Have a second helicopter available, if possible.
	Mission recommendations
Personal survival equipment	All pilots and rescuers should carry personal survival kits with pharmacologic prophylaxis for high-altitude illness. (Table 2)
Supplemental oxygen	Adhere to regional aviation regulations (Table 3) or, in their absence, Oxygen is: ◦ Optional: duration <30 minutes below 4000 m. ◦ Recommended: duration >30 minutes between 3500 and 4000 m. ◦ Mandatory: any duration above 4000 m.
Pharmacological prophylaxis for high-altitude illness	On supplemental oxygen: No need for pharmacological prophylaxis if adequate oxygen supply for entire mission. Without supplemental oxygen: Pharmacological prophylaxis is recommended for rescuers rapidly ascending to >3500 m for >3 hours.
Aircraft performance	Optimize cabin weight. Adjust for altitude effect on true airspeed, fuel consumption, and power requirements. Adjust for tropospheric and temperature effect on pressure altitude.
Reducing exposure time	Determine the best landing strategy. Minimize ground time.
Human external cargo (HEC)	Determine the optimal HEC strategy and line length. Ensure safety of the attendant.
Intermediate staging area	Choose a site with acceptable mountain hazards at a safe elevation for rescuer acclimatization and helicopter performance. Have a second helicopter and/or ground rescue team at the staging area, if possible.
Rescue site	Prepare a safe landing zone and travel path. Establish communication with the ground team.
Patient destination	Determine the optimum final destination, based on patient’s condition.
	Post-mission recommendations
Rest and recovery	Allow sufficient time for rest and recovery for both rescuers and pilots. Restock rescue equipment.
After-action review	Conduct an after-action review with incident command, operational, and medical debriefs.
Psychological stress	Train to recognize, prevent, and manage occupational stress conditions.

Table 2.

High Altitude Survival Kit for Rescuers and Pilots Unable to Descend Following Rapid Ascent >3500 m

	High altitude survival kit for rescuers and pilots
1	Oxygen Supplementation
2	High-altitude illness prevention and treatment for duration >3 hours following rapid ascent >3500 m:
	AMS: Acetazolamide 250 mg by mouth every 12 hours
	HACE: Dexamethasone 4 mg every 6 hours by any route (start with 8 mg for treatment)
	HAPE: Nifedipine 30 mg sustained release by mouth every 12 hours or 20 mg sustained release every 8 hours
3	Personal safety equipment including but not limited to, appropriate footwear, adequate clothing, personal shelter, sleeping bag and climbing equipment (if required) to safely descend if egress is required or to spend the night.
4	Food, hydration, stove and fuel.
5	Standard first aid kit
6	Consider portable hyperbaric chamber on site or at base camp if overnight stay is anticipated

Prophylactic medications should be initiated if duration at altitude is expected to be > 3h.

AMS, acute mountain sickness; HACE, high-altitude cerebral edema; HAPE, high-altitude pulmonary edema.

Table 3.

Regional Regulations for Supplemental Oxygen for Helicopter Pilots and Crew

	Canadian Transport Agency (Government of Canada, 2023):
Oxygen required for:	Aircraft operators (pilots) and all occupants flying to altitudes from 10000 ft (3048 m) to 13000 ft (3962 m) for flights longer than 30 minutes Aircraft operators (pilots) and all occupants flying above 13000 ft (3962 m) for any duration
	Federal Aviation Agency (USA) (Federal Aviation Administration, 2021):
Oxygen required for:	Aircraft operators (pilots) flying to altitudes from 12500 ft (3810 m) to 14000 ft (4267 m) for flights longer than 30 minutes. Aircraft operators (pilots) flying to altitudes above 14000 ft (4267 m) for any duration Aircraft operators (pilots) and all occupants above 15000 ft (4572 m) for any duration
	European Union Aviation Safety Agency (European Union Aviation Safety Agency EASA, 2007):
No oxygen required between 13000 and 16000 ft (3962 and 4877 m) if:	Duration <30 minutes, and pilot is experienced conducting operations at high altitude without supplemental oxygen, and pilot and crew are acclimatized, and pilot and crew have received training in hypoxia.
Oxygen required for:	Aircraft operators (pilots) and all occupants flying to altitudes from 13000 ft (3962 m) to 16000 ft (4877 m) for flights longer than 30 minutes. Aircraft operators (pilots) and all occupants flying above 16000 ft (4877 m) for any duration
	Civil Aviation Authority of Nepal (Civil Aviation Authroity of Nepal CAAN, 2013):
Oxygen required for:	All crew members and at least 10% of the passengers flying to altitudes from 10,000 ft (3048 m) to 13,000 ft (3962 m) for longer than 30 minutes All crew members and passengers flying above 13,000 ft (3962 m) for any duration

PRE-MISSION RECOMMENDATIONS

Consideration 1: Team dynamics

No single factor in VHA rescues is more important than team dynamics (Table 1). High-performing teams cultivate positive interpersonal relationships among team members long before an operation begins (Cicekdagi et al., 2023). This culture allows for efficient and effective rescues, but more importantly, it fosters the expectation that safety is of the utmost importance. A team will abort a mission if the hazards cannot be properly managed. Training, simulation, and experience with rescues at VHA create a bond of trust among team members.

Implementing an incident command system (ICS) promotes a coordinated, efficient, and safe response in rescues regardless of altitude. The ICS provides a standard framework with a modular structure that allows it to adapt to the size and complexity of the incident, from large multi-agency responses to a simple two-person response.

The Incident Commander establishes strategic objectives, while designated branches manage specific aspects of the mission. The Air Operations Branch coordinates flight plans, addresses altitude acclimatization, mitigates aircraft limitations, formulates landing strategies, manages external cargo, and develops destination plans.

Accident investigations have revealed that human error, not mechanical failure or pilot skill, was the primary cause of many mishaps. Crew Resource Management (CRM), as defined by the Royal Aeronautical Society (Royal Aeronautical Society, 1999), is a system that uses all available resources to enhance safety and efficiency, addressing human factors in rescue operations while optimizing performance and fostering effective teamwork. It emphasizes cognitive and interpersonal skills including communication, situational awareness, decision-making, leadership, and collaboration. Aviation agencies such as the FAA and the EASA prioritize CRM training, emphasizing shared mental models, standardized procedures, and clear communication to reduce error and enhance mission success. Personnel should actively participate in conversations and analyses of mission risks and should feel empowered to express their opinions on mission feasibility.

In helicopter rescues at VHA, where environmental conditions are challenging, aircraft performance is degraded, and margins for error are narrow, CRM and ICS are essential. These missions often involve multi-agency coordination, time constraints, limited visibility, hypoxia, and unpredictable terrain, leading to heightened stress and cognitive overload. Robust interpersonal coordination and shared situational awareness are of paramount importance. Crews should communicate effectively, execute procedures flawlessly, and adapt to rapidly evolving conditions while maintaining team cohesion. ICS and CRM ensure that pilots, rescue specialists, and support personnel operate in accordance with a unified framework, minimizing errors and enhancing safety for both rescuers and those they save.

Consideration 2: Training

Frequent training for VHA rescues is essential.

Rescuers and pilots

Ensure familiarity with VHA-specific gear and techniques. Operational training using case simulations increases familiarity, builds experience, and provides opportunities for quality improvement. We also recommend training in recognition and management of altitude-related cognitive and physical impairment, HAI, cold exposure (hypothermia), and localized cold injury (frostbite).

Pilots

We recommend flight time in mountain environments with experience in proximity flying and rescue techniques such as single-skid, toe-in, and hover exit/entry procedures (STEP), and human external cargo (HEC) at VHA using specialized equipment (e.g., basket, drop bag, extra-long line). Training should be integrated into programs at least annually. Agencies should establish standard training procedures tailored to their operating environments, typical rescue scenarios, and emergency procedures.

Consideration 3: Acclimatization

Acclimatization is the physiological process that takes place at altitude over days to weeks allowing the body to tolerate the decrease in oxygen partial pressure at high elevation. Individuals vary in the speed and extent to which they acclimatize (Mallet et al., 2023). A person is considered acclimatized after spending enough time at or above the rescue altitude to feel well enough to perform effectively. Ideally, pilots and rescuers should be acclimatized to operational altitudes, although the urgency and unpredictability of rescues may prevent universal acclimatization.

Consideration 4: Meteorological conditions

Strong winds, turbulence, extreme cold, radiation, and rapid changes in weather at VHA create challenges for helicopter operations (Burtscher et al., 2018; Kupper et al., 2003). Winds are the most challenging factor in any helicopter maneuver at VHA. While steady, strong winds from the “right” direction can enhance performance, unfavorable winds can make maneuvering near terrain impossible.

Aircrafts are susceptible to icing at cold temperatures, especially in fog, precipitation, or clouds. Loading passengers internally at low temperatures increases the risk of humidity inside the cabin, with fogging or freezing of windshields. Aircraft heating and demisting systems are unreliable at VHA.

Consideration 5: Pre-flight risk assessment

Safety of the rescue team is critical. A team should perform a structured risk assessment prior to every VHA mission, including VHA-specific considerations to enhance operational planning for the safety of pilots and rescuers (Fig. 1).

FIG. 1.

Example of a risk assessment matrix for helicopter rescue at VHA (courtesy of Air Zermatt). VHA, very high altitude.

Consideration 6: Backup ground rescue plan

Alternative rescue options are crucial in VHA missions, because flight operations may not always be possible. Air rescue operations may have to be aborted because of adverse weather, strong winds, incorrect patient location, inadequate aircraft performance, multiple casualties, darkness, or fuel limitations. In such cases, a ground rescue team or second helicopter should be available to provide redundancy and support. Combined ground and air rescue operations have been found to be very effective in large retrospective studies (Wang et al., 2009). Effective communication is essential whenever combining terrestrial and helicopter rescue responses.

Consideration 7: Contingency plan for aircraft grounding

Rescuers and pilots should prepare for potential aircraft grounding and for being unable to descend from VHA by air. A contingency plan helps reduce exposure and the risk of HAI. The plan should include: 1.

Predetermined ground egress route,

Personal high-altitude survival kit (Table 2),

Alternate helicopter evacuation option, and

Location and communication equipment.

MISSION RECOMMENDATIONS

Consideration 8: Personal survival equipment

Unacclimatized rescuers stranded at VHA run a risk of HAI (Table 1). This risk can be mitigated by the use of personal survival equipment. Rescuers and pilots should carry survival kits for overnight stays in the VHA environment, including medications for prevention and treatment of HAI (Table 2).

Consideration 9: Supplemental oxygen

Supplemental oxygen improves cognitive and physical performance at VHA (Falla et al., 2024b). Regulations for supplemental oxygen for pilot and cabin crew have been established by aviation agencies (Civil Aviation Authroity of Nepal CAAN, 2013, European Union Aviation Safety Agency EASA, 2007; Federal Aviation Administration, 2021; Government of Canada, 2023) (Table 3).

Helicopter rescue teams should adhere to regional regulations. In the absence of regional regulations, teams should follow the following recommendations for supplemental oxygen during flight: 1.

Optional: duration <30 min below 4,000 m.

Recommended: duration >30 min between 3,500 and 4,000 m.

Mandatory: any duration above 4,000 m.

While no regulations exist for rescuers exiting helicopters at VHA, we recommend the use of supplemental oxygen to improve cognitive and physical performance (Falla et al., 2024b). We recommend small, lightweight canisters with masks or nasal prongs that allow effective communication. Teams should ensure adequate oxygen pressure and supply and should estimate the duration of supplementation before deployment.

Decisions regarding oxygen delivery systems (mask vs. nasal prongs or on-demand vs. continuous flow) depend on communication needs, weight, duration, cost, availability, and rescuer preferences. Typical rescue flow rates range from 2 to 4 l/min, although there is limited evidence for matching oxygen flow rates to specific altitudes. At 5,050 m, a supplemental oxygen flow rate of 3 l/min is more effective than 1 l/min in reducing AMS symptoms and perceived exertion (Silva-Urra et al., 2011). At simulated altitudes above 8,000 m, flow rates of 1–2 l/min at rest and 2–4 l/min during exercise were sufficient to maintain oxygen saturation at a level mitigating hypoxemia-related symptoms (Wakeham et al., 2023). No studies specifically address pilot or rescuer oxygen flow rates for rapid ascent rescue. Oxygen saturation monitoring may be used during flight but is impractical during ground rescues at VHA.

Consideration 10: Pharmacological prophylaxis for high-altitude illness

Pharmacological prophylaxis to reduce the incidence of HAI has been recommended for rescuers rapidly ascending above >3,500 m while performing physical work (Luks et al., 2024). However, these guidelines do not differentiate between terrestrial and helicopter rescue, pilot and rescuer, rate of ascent, VHA mission duration, or supplemental oxygen use.

Onset of AMS can occur within 6–12 hours, doubling in severity for each 1,000 m increase in altitude (Bartsch and Swenson, 2013). Personnel using supplemental oxygen do not require pharmacological prophylaxis unless exposure to VHA exceeds oxygen supply. For personnel not using supplemental oxygen, pharmacological prophylaxis for AMS/HACE is indicated for rapid ascents above 3,500 m lasting >3 hours at VHA (Mclaughlin et al., 2024). Typical acetazolamide dosing for AMS prevention in trekking is 125 mg every 12 hours. However, because of the higher risk for HAI with rapid ascent to VHA, 250 mg of acetazolamide every 12 hours has been recommended (Luks et al., 2024), although this dose has not been studied in this population. The ultimate decision on acetazolamide dosing should be determined by the level of acclimatization, altitude change, and rate of ascent. If immediate deployment is not required, we recommend that acetazolamide 250 mg every 12 hours be initiated the day before rapid ascent to VHA. For immediate deployment, we recommend dexamethasone 4 mg every 6 hours. If ascending above 5,000 m or if prolonged physical activity at VHA is required, combined therapy with both acetazolamide and dexamethasone should be used (Mclaughlin et al., 2024).

Rescuers with a history of HAPE are at risk of recurrence if rapidly ascending to VHA and should avoid such missions especially if there is a risk of prolonged exposure (Bartsch et al., 2002). If they must ascend to VHA, they should use supplemental oxygen. If oxygen is not available, slow-release nifedipine 30 mg every 12 hours or 20 mg every 8 hours should be started prior to deployment for HAPE prophylaxis.

Consideration 11: Optimizing aircraft performance

Helicopter performance at VHA is negatively affected by reduced barometric pressure and reduced oxygen saturation, temperature, wind and air moisture (Federal Aviation Administration, 2024). Low air density reduces aerodynamic efficiency and lowers main rotor and tail rotor thrust, diminishing lift and control authority [European Helicopter Safety Team (EHEST), 2017]. At VHA, aerodynamic efficiency of rotor systems requires a higher pitch angle for a given weight. As altitude is increased, the power output required is also increased. Engine power output is limited at VHA, restricting the amount of weight that can be carried. Pilots must minimize aircraft, personnel, and equipment weight to achieve the required performance.

Atmospheric conditions, helicopter weight, and engine performance determine the altitude limit for hovering. Power reserves are essential for safe maneuvering and hovering at VHA (Federal Aviation Administration, 2024).

Gas turbine engines are less affected by altitude than aspirated piston engines because they actively compress the air before combustion. This allows them to maintain power even in thin air at VHA, while piston engines rely on atmospheric pressure to draw in air, making them less efficient at VHA (Gasmire, 2025).

Fuel plays a crucial role in determining the type of extraction or insertion being flown, mission duration, and maximum load capacity. Aircraft at VHA consume less fuel because of reduced air density. Precise fuel calculations are required to achieve optimal weight for the mission and safe return to fuel cache or landing zone. Burning excessive fuel to augment cargo capacity at VHA is time-consuming and can be problematic because of weather, daylight, and patient conditions. Fuel expansion occurs at VHA. Although this does not impact fuel planning, it can influence fuel additive selection below −35°C. Fuel additives and airframe fuel filters help prevent water molecules from freezing in fuel.

Because of lower air density at VHA, true airspeed exceeds indicated airspeed by 1 Knot (Kt) per 300 m elevation gain. For example, at 6,000 m, the airspeed indicator should read 45 Kts to achieve true airspeed of 65 Kts. The calculated reduction in indicated airspeed should be performed to maintain accepted mountain flying reconnaissance true speeds of 40–60 Kts and prevent excessive landing speed.

Retreating blade tip stall is a major contributing factor that prevents helicopters from achieving faster flight speeds at VHA. Higher altitude and greater gross weight reduce the speed at which retreating blade tip stall occurs. At 6,700 m, the pilot can start to feel the retreating blade stall at an indicated speed of 60–65 Kts.

Latitude and temperature affect helicopter performance because the troposphere is thinner, and temperature is colder near the polar regions compared with the equator. On Mount Everest, the pressure altitude can be 560 m lower than true altitude during the spring climbing season (Helman and Sype, 2006). Near the Arctic Circle, the summit of Denali can have a pressure altitude 500 m higher than the true altitude of 6,190 m.

The ideal VHA rescue helicopter has: 1.

Low weight,

Powerful engines with efficient rotors,

Adequate payload capacity,

Stable maneuverability and precise hovering capabilities,

Advanced avionics for challenging mountain environments,

Excellent visibility for the pilot during HEC, and

Ample open floor space for patient, gear, and rescuer.

The H-125 (Airbus, France) is widely used, but the B-407 (Bell, USA) or A-119 (Agusta, Italy) are also suitable for rescue missions at VHA. Powerful heavy-lift helicopters generally underperform at VHA because of poor power-to-weight ratios and high fuel burn rates. Innovative helicopters such as the AW09 (Leonardo Kopter, Italy) enhance VHA capabilities with lightweight carbon fiber bodies and high-performance engines.

Consideration 12: Reducing exposure time

Flight duration at VHA should be as short as possible to reduce hypoxic physical and cognitive impairment and risk of HAI. Exposure to VHA can be reduced by: 1.

Pre-mission logistics planning,

Conducting a reconnaissance flight,

Assessing weather and wind,

Predetermining the minimum number of required flights, and

Predetermining helicopter rescue technique.

Ideally, a land-and-load should be performed in the vicinity of any patient requiring evacuation. At VHA, land-and-load is generally better than hover-loading because power may be a limiting factor. When there is no suitable landing zone or environmental conditions are not suitable, power-on landing techniques may be used to insert rescue personnel or extract patients.

STEP are power-on landings in which a single skid is placed on terrain, with the front aspects of both skids in a toe-in or hovering just above terrain while rescuers step out onto terrain. STEP operations are challenging at VHA, as the rotors are in close proximity to terrain. STEP operations require sufficient power, debris-free zones, effective communication, and whiteout risk mitigation. If these conditions are not met, human external cargo (HEC) operation is safer.

Prolonged durations at VHA may be required for extended groundwork during crevasse, avalanche, or cliff rescue. The pilot should decide whether to remain on site or descend to lower altitude until extrication. Powering down should generally be avoided at VHA, because there is a risk of failure to restart the engine.

Consideration 13: Human external cargo (HEC) operation

Challenging terrain, inadequate landing zones, and adverse weather conditions at VHA may restrict landing options. Additionally, landing in snow can lead to a whiteout, posing a significant risk to the safety of the helicopter and potentially rendering it incapable of escape. When landing is not feasible, pilots may need to transport rescuers or patients externally.

HEC operations position the rotor further from terrain, rescuers, patients, and debris. HEC operations also allow for hovering in cleaner air, reducing air turbulence. This enables more room to escape terrain, whether in an emergency situation or because of problems with wind gusts, while allowing for precise rescuer insertion and patient extraction, without requiring high-risk landings or difficult hovers. In a study of 11,078 air rescue missions in Switzerland, 10% required HEC operations (Pietsch et al., 2019).

HEC operations are divided into two categories: short-haul and hoist. In short-haul operations (heli-sling or long-line), rescuers are attached to a fixed length of rope that is connected to hooks on the underside of the helicopter for a short duration of flight. This technique requires the team to land at an intermediate staging area to configure for HEC operations.

Hoist operations involve a mechanical hoist mechanism that enables rescuers to deploy on a cable from the aircraft. Because of the increased weight, crew requirements, and equipment, hoisting is not an option for VHA rescue work. Short-haul is the preferred strategy.

The optimal short-haul HEC tactic depends on the weight of the external load, effects on helicopter performance, rescuer acclimatization, location, and the patient’s medical condition. It is not always possible to carry a rescuer. A pilot may have to accomplish a mission alone. Short-haul options are as follows: 1.

Inserting one rescuer and extracting two people (rescuer and patient). The rescuer can detach or remain connected to the short-haul line while the helicopter hovers, depending on the terrain and the risk of leaving the rescuer at altitude.

Inserting one rescuer, then extracting the patient alone before extracting the rescuer on a subsequent flight.

Inserting an empty line and extracting a single patient, often with the help of ground rescue team, or attaching a radio to the short-haul line to allow for communication with pilot.

Inserting an unattended rescue basket on the short-haul line and then extracting the patient in the basket.

The length of the short-haul line depends on the situation. Denali National Park has conducted extensive testing with line lengths at high altitude and found that there is still significant downwash with a 100 ft (30 m) line, rendering this length inadequate. With the H125 airframe, a 150 ft (50 m) line is preferable. To improve terrain clearance and minimize mechanical turbulence caused by mountainous terrain, a longer line of 200–250 feet (61–76 m) should be used. The longer line provides cleaner air and allows for improved aircraft performance. Although the longer line may reduce the pilot’s ability to see the load or rescuer’s hand or head signals, it improves radio communication because of greater distance from the helicopter.

Direct helicopter-to-rescuer and rescue site communications are essential. If the rescuer or rescue site lacks a radio, the rescue team should consider dropping a bag with a radio and survival gear during the reconnaissance flight.

Rescuer selection is critical for HEC operations. For VHA, rescuers should be experienced, capable, acclimatized, lightweight, and should carry light equipment. Pilots and rescuers should undergo occupational medical screening to exclude pre-existing conditions that may be contraindicated in VHA exposure (Kupper et al., 2003). Rescuers with acute illness or chronic ear, nose, or throat conditions should be excluded. Pilots should insert unacclimatized rescuers as close as possible to patients to minimize rescuer workload at altitude.

Cold exposure is increased during HEC operations because of windchill, increasing the risk of frostbite or hypothermia. HEC rescuers should wear adequate clothing for extended exposure and prepare their subjects for the same conditions.

Experienced physicians should be present during HEC rescue missions at lower altitudes (Pietsch et al., 2019). In contrast, during medical rescues at VHA, physicians typically remain at base camp or lower-altitude staging areas while the pilot and medically trained rescue specialists execute the patient extraction and subsequent transport to the physician for stabilization before transfer to a definitive care facility.

Consideration 14: Staging (intermediate landing) areas

Staging, or intermediate landing areas, can be used to set up short-haul lines for HEC operations, position medical or rescue personnel, cache fuel, land a second aircraft, or store additional rescue equipment. The area should be close to the rescue site to reduce flight distance, allowing less fuel to be carried. This area should also have: 1.

Minimal exposure to mountain hazards,

Safe altitude for unacclimatized rescuers,

Optimum elevation for helicopter landing performance, and

Sufficient space for patient care and a second helicopter.

Consideration 15: Rescue site

Rescue site preparation at VHA generally follows standard procedures for lower altitudes, including establishing a landing zone, securing loose equipment, and creating a well-marked, established path to and from the landing zone to ensure patient and rescuer safety. Challenges at VHA are caused by difficult terrain and altitude-related movement restrictions.

Consideration 16: Determining patient destination

Mission planning should determine the most appropriate final patient destination based on medical condition. Initial extraction may involve patient transport to an intermediate staging area for assessment, stabilization, and secondary air transport to definitive care. Knowledge of the local medical centers specializing in HAI, cardiac arrest, and trauma management can optimize patient outcomes.

POST-MISSION RECOMMENDATIONS

Consideration 17: Rest, recovery, and restocking

Because of the physical and mental stress of VHA rescues, adequate post-mission rest and recovery are essential for individual and team performance (Tuckey and Scott, 2014). We recommend full recovery at lower altitude before redeployment. Equipment should be cleaned and restocked in preparation for the next mission (Table 1).

Consideration 18: After-action review

Complex helicopter rescues involving HEC impose high stress levels (Vicente-Rodriguez and Clemente-Suarez, 2021). VHA rescue operations add further physiological and logistical stress. A post-mission review of incident command, operational tactics, and medical care can enhance future team performance and reduce psychological burden (Tuckey and Scott, 2014). Reflection on decision-making, team coordination, and equipment performance can enhance quality improvement.

Consideration 19: Psychological stress

Awareness of occupational stress injury should be integrated into VHA operational training. Field training for stress recognition and mitigation should be standard practice. Preparation, simulation, and experience can help reduce operational stress (Ellerton, 2023). Establishing a unified language to address psychological stress, creating support systems within the team structure, and using specialized support mechanisms from clinicians trained in recognizing and managing occupational stress can improve stress resilience (Ellerton, 2023; Mikutta et al., 2023; Responder Alliance, 2025).

Limitations

The primary limitation is the lack of research on high-altitude helicopter rescue. Many of our recommendations are based on expert opinions of experienced pilots and high-altitude rescue specialists. Future studies should focus on optimizing helicopter operational performance, use of supplemental oxygen and pharmacological prophylaxis for rescuers, and preflight risk assessment and mitigation.

Conclusion

Our international collaboration among pilots, rescuers, and physicians involved in high-altitude rescues outlined 19 considerations for optimizing safety and operational success in VHA helicopter rescues. These recommendations can serve as a foundation for international guidelines and for developing organization-specific rescue protocols in VHA environments.

Authors’ Contributions

K.M., C.S., I.J., G.B., and M.F. contributed to the design, research, and results of the article. All the authors contributed to the writing of the article. K.M. and C.S. supervised the project.

Footnotes

Acknowledgment

The authors thank ICAR MedCom and ICAR AirCom for critical discussion of this article.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

Supplemental Material

References

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