The 10 Biggest Threats for Air Ambulance Helicopters | EASA Community (2024)

This article was first published on Pilots Who Ask Why.

Helicopters have a lot of threats to overcome on a daily basis. From tail rotors without redundancy, to all the moving parts and the aerodynamic counter-forces to actually stay in the air. But the biggest threats for air ambulance helicopters (and causes of accidents) aren’t actually mechanical issues, but more operational and environmental factors.

When we look at the global aviation stats, helicopters do not stack up well against fixed wing stats at all! Why? Well, it has a lot of reasons, some of which we’re going to cover here!

If we zoom in on the Helicopter Emergency Medical Services (HEMS) industry (or air ambulance, depending on your part of the world), this issue gets even worse because of the nature of the operation they get involved with, and the conditions they get flown in. So what are the biggest threats for air ambulance helicopters, and are they going to stick around in the future?

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1. Controlled Flight Into Terrain

Controlled Flight into Terrain (CFIT) is one of thebiggest reasonsfor the poor safety reputations of the rotary wing industry. CFIT happens when a plane or helicopter inadvertently flies into terrain, obstacles, or water, usually due to poor visibility conditions. The risk of CFIT accidents occuring has been linked by various safety organisations to:

  • Flying at low altitudes and in challenging weather conditions, in order to reach patients in remote or inaccessible areas
  • Poor weather conditions
  • Complex terrain such as mountains and valleys
  • Communication errors between flight crew, but also with crew on the ground and flight dispatch
  • Instrument errors or malfunctions
  • Pilots refusing to climb to a minimum safety altitude and continue IFR, either due to circ*mstances or improper training / recency.
  • Poor flight crew terrain awareness
  • Pressure to continue the mission when the decision to return to base should be made

Interestingly, the decision from helicopter pilots NOT to continue IFR has been a talking point for a very very long time, and is still not properly addressed.

Various factors play in to this, from not having viable helicopter IFR options or infrastructure, not being able to carry enough fuel (more on this below), to simply not feeling confident enough due to competency / recency issues.

How will we address this as an industry? We’ll cover this in the future, but unfortunately there is no clear cut answer at the moment.

2. Inadvertent Entry Into IMC

So while a planned conversion to IFR doesn’t happen enough according to safety statistics, the ‘unplanned’ version happens very often: Inadvertent Entry Into IMC (IIMC).

Pushon-itis is a big one here. Picture this: Flight crew get dispatched to a horrible accident on a motorway. Kids are involved in the accident, all required resources are on scene but a helicopter is required due to the severity of injuries: everyone wants to help.

The air ambulance dispatches, weather is great at base but there are no weather observation stations near the scene. Enroute, the crew finds themselves descending more and more due to a reduction in cloud base. Radalts get set to the mimimum allowed setting, and the crew thinks to themselves “we don’t really want to descend any more than this”.

After flying for 40 nautical miles, with 2 miles to go, the weather turns below limits.

What do you think could happen here? If we look at all accident reports from the last 20 years, there is a predictable course of action here. Of course the safest decision is to not get ‘sucked in’ and declare weather unsuitable and return back to base.

However, unfortunately the decision that’s made before these accidents happen is often to push on, as ‘we got this far, right?’. Sunk cost fallacy, pushon-itis, self induces pressure, hero-ism, macho attitudes, ego, and LOTS of other reasons play into this.

Unfortunately, the deck is stacked against us if we allow primal urges to take over our brains. Situations like this (not just in the air ambulance industry) have led to countless IIMC events and often do not end well for anyone.

It’s these moments that define us as pilots. Do we listen to our emotional, or rational side of our brain? Do we safely return to be able to dispatch to a different job, or do we push on while taking on an unacceptable amount of risk?

Of course there are always other solutions such as to rendez-vous with an ambulance, or crew collection vehicle at a location where weather is suitable, but this decision isn’t always made in the cases that have been widely researched.

The industry push to get helicopter pilots IFR rated, even the ones who primarily fly VFR, has been one of the attempts to address the issue. Stats will still have to come on in on whether this has made a substantial difference, as it might not be enough.

Having an Instrument Rating (IR) will obviously make you more inclined to consider IFR as an option compared to not having an IR, but is it enough?

Does a pilot flying in poor conditions under high workload feel comfortable enough to rely on skills he only uses 3 times every 90 days for currency purposes? The other issue is that going IFR usually means the mission can’t be completed due to distances to airfield and the time it takes to conduct a full IFR approach procedure. Only time will tell once we get the data.

3. Lack of Weather Data

Weather is one of the most significant threats facing air ambulance helicopters. Poor weather conditions such as thunderstorms, heavy rain, fog, poor visibility, low cloud bases and strong winds, can make it difficult for flight crew to safely operate. Decision making is key here.

Even if the helicopter is allowed or able to take off and land, flight crew may be forced to reduce altitude and speed, increasing the time it takes to reach the patient. In addition, it’s possible that the weather allows for a take-off, but a landing at the destination is not guaranteed, which makes the entire operation more complex, requiring more plan B’s , C’s, etc.

The benefit of a helicopter though, is that if at any point you’d rather be on the ground than in the air, you could just select an ad-hoc landing site anywhere on the ground that is suitable, and land! Plenty of fixed wing pilots who would love to have that luxury!.

The question is however what you were doing to require such a site. If the weather conditions are that bad, you probably shouldn’t have been flying in the first place?

To this day, weather is still the largest obstacle to overcome for air ambulance helicopters, and is also one of the causes of a lot of threats discussed below.

The other factor that’s often overlooked is that air ambulances usually do not fly to airports, which means that weather reporting facilities are generally not available. Also, there are lots of air ambulances flying in the middle of nowhere, with no airport within the entire area! This means that weather decisions will have to be based on forecasts, which could be very unreliable. Good decision-making relies on accurate data!

This is especially true if you’re flying in an area where there are a lot of microclimates, such as near coastlines, ridge lines, mountains or forests.

The weather could be great before take off, but you know there is a massive front approaching with conditions that are unsuitable for safe flight. Do you take the mission knowing you’re going to strand the helicopter? We can’t always just look at a METAR / TAF and decide based on that, unless we’re flying to an actual airport, which is rare.

No situation is black or white, and lots of pilots will have a different opinion on various situations. Knowing where you are on the scale from very conservative to more risk-taking behaviour is helpful to debrief yourself after every flight, and to see where you can improve.

4. Commercial and Self-Induced Pressure

Across the aviation industry, commercial and self induced pressure still has a massive impact on flight safety,as we discussed here.

The mud-flinging contest on whether it’s self induced or commercial pressure is kind of pointless. At the end of the day, pilots still make decisions that are infected by something that isn’t flight safety. How do we train ourselves to make decisions that are in line with a safe outcome?

Why do pilots fly into mountains? Why do they take off in fog? Why did they push on below limits and flew into a power line? Why did they refuse to go back to base and live another day? The answer has been commercial or self induced pressure for way too many times.

For air ambulances, the nature of the job is often one with lives at stake. They’re there to help, we get dispatched to help. Training and awareness is the answer here. Being aware of the urge to push into conditions you’re otherwise not comfortable in, is crucial to address the issue. Would I push out in this if the patient wasn’t in the circ*mstances that he is currently in?

Most operation manuals mention the responsibility of the pilot to weigh off the medical risk of the patient to the aviation risk. But this shouldn’t mean that once someone is dying on the ground, we can just ignore the rules and do whatever we want to get to scene.

Interestingly there are parts of the world where the flight crew do not get told what type of patients they are flying to, to protect flight crew from emotional pressure. Do you agree with this? An argument can be made for having all data available to make informed decisions, but there are lots of counter arguments as well.

But it’s not just HEMS. It happens all across global aviation, in lots of different aviation sectors. Regulators will have to step in. Companies across the globe have to juggle profit making and flight safety. These are 2 factors that are often on opposite sides of an argument.

Plenty of accident reports and recent events (look at the B737 MAX) is comparable to asking the fox to guard the hen house. Businesses have 1 priority: profit. You can’t blame them for having this goal, they’re businesses for a reason, although flight safety has to be a priority too! Regulators need to step in and make sure that this responsibility isn’t an ‘option’, but a requirement.

Why hasn’t commercial pressure been addressed by regulators? A poster every once in a while to say ‘don’t give in to commercial pressure’ isn’t good enough. How do we know that? All you have to do is look at the latest 100 VIP helicopter crashes and the answer becomes very clear, more on this in the future.

5. Drones and Birds

Helicopters fly low. Drones and birds fly low. A bunch of seagulls aren’t going to NOTAM their intentions, nor is the kid who just got a new drone for his birthday.

Again, awareness, planning, and vigilant behaviour are the only remedies for threats like these. Working together as a crew and flying defensively to expect the unexpected can work really well to address these issues.

As we grow more experienced as pilots, it’s possible that we become more complacent about issues that have not caused any harm to us over the years. You might not have had a bird strike after 35 years of flying in the same operating conditions. That unfortunately doesn’t mean you won’t have a bird fly into your rotor disc or engine today or tomorrow though.

From my own personal experience, drones have mainly been an issue during the landing stage when we get even lower in an uncontrolled site. People are excited to see a helicopter land and just start filming, with either cameras or drones.

Bird and drone strikes have their own little part in global aviation accident stats, and will probably continue to do so. The only remedy is situation awareness and to not let our guards down while flying.

6. Relatively Low Fuel Capacity

Fuel capacity = options! Decision making is always easier to manage when you have options. Unfortunately, especially when it comes to IFR flight operations, helicopters often don’t have great fuel capacities when they’re also loaded with medical equipement, patients, and medical crew.

It’s a delicate balance between carrying enough equipment to be able to do the job, while also having enough fuel that ‘you might not use’. It’s a hard sell to someone who isn’t familiar with aviation, or has a mission to accomplish using a helicopter.

More efficient helicopters that have been designed over the years have made things slightly better. However, compared to our fixed wing friends flying the long tubes with wings filled with massive amounts of fuel, we still have a lot to improve on when it comes to fuel capacity.

Even something like an unplanned VFR to IFR conversion in flight comes with the question of ‘do we have enough alternate fuel’, ‘are we legal to convert to IFR here in regards to our fuel capacity’? Often, the answer is a pretty clear no due the nature of the job.

These are questions that are very necessary but often push pilots away from safely converting to IFR, with the fear of forgetting something in the moment. Another reason to incorporate this into the planning stage, although this could be difficult due to large amount of unknowns.

7. Flight Crew Fatigue

Fatigue is another significant threat to air ambulance helicopter crews, which we covered extensively inthis previous Pilots Who Ask Why article.

From waking up by an alarm at 2 AM when the mission comes in, to flying in poor weather, low level, in a complex aircraft with lots of variables to consider, only half an hour later. It’s not a transition humans are designed for.

Not only this, but night shifts are often 12 hours long, with periods between 0200 and 0600. This has been proven to not only have long term health consequences, but it also comes with the challenge of dealing with the fatigue itself while flying at those silly times.

Luckily HEMS is slowly moving towards a multi pilot environment, where pilots can help each other and can cross reference data and decisions. There are still lots of air ambulances across the globe that are flown single pilot though, and it will be interesting to see how this develops in the future.

8. Uncontrolled Landing Sites

The nature of HEMS means that most of the landing sites are uncontrolled. Uncontrolled landing sites pose a threat due to the fact that there are a lot of unknowns at the site, that could be hard to spot during the recce.

While tools are available to spot threats like power lines, elevation differences, or even covered reservoirs, there will always a risk for things to be there that are hard to plan for, or spot during the recce. A farmer could’ve built a mast that takes a random power cable across a field, there could be a kid at the site flying a drone or a kite, etc. None of this could ever be planned for on a plate or pre-flight briefing, other than to expect the unexpected and to be attentive throughout.

The 10 Biggest Threats for Air Ambulance Helicopters | EASA Community (1)

The other risk is brownout or foreign object debris (FOD). The risk of damaging public property or causing harm to people because of objects being blown around by rotor downwash is always a factor, and needs to be mitigated. If, during the later stage of the approach, downwash is observed to be a factor, a go around should always be considered.

9. Hostile Terrain

Then there’s the terrain. Whether in congested areas or not, hostile terrain can be tricky to deal with for air ambulance flight crew. Depending on the country you’re in, most hospital landing sites require performance class 1 to be adhered to, while HEMS operating sites can be flown to while using performance class 2, as we discussed inour performance class article.

This means that when flying to a hospital, extra care must be taken to make sure you’re flying the correct profile, with appropriate reject or go-around options available, if a malfucntion occurs. Not to mention not overflying hospital buildings, following noise abatement procedures, and ensuring a safe approach path with a headwind component.

During the approach, things like trees, masts, car parks, people, wires, buildings and vehicles can all present a threat. If you’re flying HEMS with only 1 engine (like sometimes in the USA), always making sure you have a safe forced landing area available in case of an engine failure can be a challenge.

10. Human Error

Human Error is still one of the largest factors influencing aviation, as we’ve covered inthis article.The only way we can improve this is by proper training, CRM awareness, flat co*ckpit hierarchies, and a just culture within aviation companies (we’ll cover this one in the future).

Proper decision-making, whether multi pilot or single pilot, is often the difference between a serious accident and a safe flight. All the threats discussed earlier can all be mitigated with rational and thorough decision making, preferably as a team.

We’ll cover this topic more extensively in the future, but human factors as a whole has a lot of different ways in which it can influence incidents or accidents. Factors like fatigue, personalities, stressors, distractions, teamwork and many others are all hugely relevant and will stay that way, until we all get replaced by AI.


Threat management will continue to be hugely relevant for the air ambulance industry. The threats discussed here are not an exhaustive list, but are the biggest factors that influence flight safety for helicopter flight crew. We will cover threat error management very soon that will tie into this article!

The 10 Biggest Threats for Air Ambulance Helicopters | EASA Community (2024)
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