Helicopter emergency medical services are demanding operations, requiring crews to maintain high standards of performance whilst often being conducted in hostile environments. One such challenge is the fact that over mountainous areas, helicopter rescues can be performed at high altitudes, with the possibility of detrimental physiological effects on crew members. Whilst exposure to the effects of altitude is normally for only a short time, given the stakes that are inherent to helicopter rescues, the impact of altitude on a flight crew’s ability to accomplish a mission is worth exploring to assess the state of the art in terms of best industry practices to deal with this issue.

“High altitude impacts our pilots and crews on a daily basis,” says Oliver Kreuzer of the training centre of Air Zermatt, a mountain rescue service provider in the Swiss Alps. “Fortunately, we all already live at 1,600 m [5,250 ft] and perform helicopter work at higher altitude on a daily basis, and are somewhat used to it – or better, we know how our bodies react to altitude and know our limits and how we perform at high altitude. But we still need to realise that the danger of the effects is always there and need to minimise the exposure.”

Standard procedure

GMH Helicopters is an Italian general helicopter operator based in Courmayeur, in the Aosta Valley, at the foot of the Mont Blanc – the tallest mountain in Europe rising to 4,809 m (15,777 ft) – and, because of its area of operation, has significant experience with regard to flying helicopters at high altitude. In order to mitigate the risk of flight crew hypoxia, GMH Helicopters has developed a standard operating procedure (SOP) that has been approved by its competent authority. 

high altitude impacts our pilots and crews on a daily basis

“Our SOP foresees that all pilots be tested at a mountain medicine and neurology centre before starting operations with us in order to verify the existence of pathologies associated with operations at high altitudes, such as hypoxia. Humans have different degrees of sensitivity to hypoxia and the purpose of the test is to ascertain whether there is hyper-sensitivity ,” says Alessandro Remine, flight operations and crew training manager at GMH Helicopters. “The same test is administered twice: once under strain and once in conditions of rest. The pilot is made to wear a mask that channels hypo-oxygenated air for him/her to breathe and different parameters are recorded such as the heartbeat and the airflow. A cognitive test is also performed that requires the pilot to make some simple mental calculations, and what is analysed through this test is whether the results are given within the time frames that are acceptable for normal oxygenation. There are different parameters subject to measurement and, based on the outcomes for each of the different parameters – heartbeat, airflow and overall oxygenation – the pilot is assessed as hyper-sensitive to hypoxia or not, and therefore whether fit to fly at altitude or not,” he adds.

The SOP also requires the pilots to undergo a training course on physiology at altitude. The course syllabus covers the symptoms and the pathologies associated with operations at altitude with particular focus on hypoxia and the symptoms deriving from scarce oxygenation. This course takes one day to accomplish whilst the medical test is conducted in approximately half a day, says Remine.

“The SOP also includes some more inherently technical aspects concerning actual flight operations management,” he explains. “Flight crew members are tasked to record by means of a chronometer the time of permanence above 10,000, 13,000 and 16,000 ft, the latter being our maximum altitude limit. For operations between 13,000 and 16,000 ft there is a maximum allowance of 10 minutes of continuing operations at those altitudes. This practice is a replication of the contents of European aviation safety regulations on specialised operations, which will become mandatory for application by August 2017.”

Aviation safety regulations issued by the European Parliament are applicable in all EASA member states — the members of the European Union plus Norway, Switzerland, Iceland and Liechtenstein.

Oxygen supply

According to Binod Thapa, executive manager for operations and sales at helicopter operator Fishtail Air of Nepal, which provides helicopter rescues in the Himalayas, weather, load factor, wind and the nature of the helipad can all contribute to generate physiological effects on helicopters pilots during operations at high altitudes. Fishtail Air employs pilots qualified to fly at high altitudes that are approved by the Civil Aviation Authority of Nepal for high altitude flight. “We prefer to send dual crews for high-altitude flights to mitigate risk should one pilot become incapacitated,” he says. In Nepal, if the flight is conducted at altitudes above 10,000 ft and the flight time is more than 30 minutes, it is mandatory to supply oxygen for passengers as well, says Thapa, adding: “Mostly, we [carry] extra cylinders and masks for passengers during mountain flight.”

humans have different degrees of sensitivity to hypoxia

When it comes to helicopter operations at altitudes, a supply of supplemental oxygen is not that easy to implement, at least in Europe. According to European aviation safety regulations dealing with commercial air transport operations, a commander is required to ensure that flight crew members engaged in performing duties essential to the safe operation of an aircraft in flight use supplemental oxygen continuously whenever the cabin altitude exceeds 10,000 ft for a period of more than 30 minutes and whenever the cabin altitude exceeds 13,000 ft. The European aviation safety regulatory framework does not easily allow supplemental oxygen supplies onboard helicopters: mobile installations are prohibited and fixed installations, whilst allowed, are not readily available.

“Oxygen qualifies as a dangerous good, and even if an operator were approved for the transportation of dangerous goods, it would not be enough as the oxygen would not only need to be transported but also supplied, thereby hyper-oxygenating the cabin and increasing the risk of fire,” says Remine. “What is possible in Nepal in terms of deploying oxygen supply installations is not possible under EASA regulations. Fixed installations are possible and are the only ones that are legally acceptable, but the problem is that there do not currently exist installations having an EASA supplemental type certificate (STC) or for that matter a US Federal Aviation Administration STC. It might become possible in the future to have approved as mobile installations the likes of vests for pilots to wear that are equipped with an oxygen cylinder and a mask, but this is not possible as of now.”

we prefer to send dual crews for high-altitude flights

Remine continues: “As far as fixed supplemental oxygen installation is concerned, it would be a significant achievement if helicopters received such STCs. The problem, however, is with costs which are high also because of the need for testing the installations. Quite honestly, the idea of flying a small helicopter like the Écureuil carrying cylinders of oxygen is a little concerning. The payload of the helicopter would not be affected significantly. The problem would rather be finding a suitable space for the safe positioning of the cylinders. The helicopter throughout a day may not need the supply of supplemental oxygen on all segments and, given the variety of roles a helicopter is used for, it is important to make sure that additional goods carried onboard do not impact with the oxygen cylinders with the possible risk of fire.”

Perhaps space would be less of an issue on larger helicopters. It should be noted, however, that there do not exist commercially available fixed installations even for larger helicopters.

Increased fatigue

Fatigue is another consequence of helicopter operations at high altitude. What is regarded as particularly fatiguing on pilots is being subject to variations of altitude rather than permanence at altitude. “Permanence at altitude per se does not cause fatigue as the operator is not working,” explains Remine. “Should permanence at altitude be in the range of hours, a pilot might experience mountain sickness with the symptoms being headaches due to mini cerebral aneurysms, but this generally never happens with helicopter rescue operations nor with aerial work.”

Variations of altitude are a different matter, though, and are a cause of discomfort. “As an example, a flight crew might be taking off at 5,000 ft AMSL and operate systematically at 11,000 ft, s/he could easily be experiencing variations of altitude as many as 25 times a day and certainly s/he is more fatigued compared with when variations are to altitudes that are under 10,000 ft,” explains Remine.

Fishtail Air’s Thapa also recognises that fatigue effects are aggravated by high altitude flying. “We are rostering our pilots for high altitude flying in order not to exceed the flight time limitations according to the law, but if a pilot is not willing to fly more due to fatigue, we certainly do not force him/her to fly,” says Thapa.

According to Air Zermatt’s Kreuzer, operations at altitude have an effect on fatigue after a mission, but recovery is usually quick. “Our rule is simple: if you feel tired or exhausted or have any effects of fatigue, you can always hand over to another crew. As long as crews feel fit to perform the mission, we fly and perform, otherwise we just hand the mission over to another pilot, paramedic and rescuer,” he says.

we carry extra cylinders and masks for passengers during mountain flight.

Remine believes that overall, the helicopter industry is not very familiar with the inherent challenges of flight operations at altitude. “[Other than] some 10 operators in the world – including ourselves who operate on the Mont Blanc – there are not many operators who have a need and therefore the experience to operate helicopters in hypo-oxygenated air,” he says. “It is important that certifying bodies and national aviation authorities become better aware of the implications of helicopter operations at altitude [and] they should simplify the development of SOPs concerning this type of helicopter operations. What we need in the end is to have a standard operation and monitor that pilots maintain themselves compliant.” He concludes: “We would welcome the opportunity to carry supplemental oxygen onboard by means of vests worn by the pilots; should this be allowed, the whole procedure would be simplified, this would be a sort of mobile installation which would suit our needs since we do not spend hours at high altitudes but halves of hours maximum.” △