Preventing Wire Strikes: 10 Key Principles for Helicopter Pilots

The 2023 helicopter safety statistics from EASA show that, for another year, collision with obstacles, like wire strikes, remains one of the largest accident categories for helicopters across the board.

An average of 76.6 aviation accidents per year in the United States involve wires or power lines, according to an FAA Safety Alert for Operators.

Why does the industry seemingly not learn from all these accidents? 💡

Wire strikes happen because of a lot of different factors, that aren’t really discussed enough in the industry.

Today, we’re going to dive deeper into how wire strikes happen exactly, and what we can do as pilots to prevent them! 🎯

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Why do Helicopter Wire Strikes Happen?

There are various factors that all link into why wire strikes are so common in the helicopter industry. So how did we get here? Let’s discuss the main reasons wires are such a threat.

Low Altitude Flight

Most helicopter operations take place at low levels. Poorer weather makes this even more difficult. An instrument approach is often not an option for helicopters, due to the remote areas they’re trying to reach. Going above cloud when conditions get worse, can present delays and other problems when trying to break cloud again.

This is the main reason why most helicopter operations take place below cloud. The side effect of this is that low cloud bases automatically mean a lower flight altitude than what you’d consider the safest.

Uncontrolled Landing Sites

Wires becomes even more of a problem when landing in places that are not designed for aviation. SAR, HEMS, and many other types of operations are all under an increased amount of risk because of this.

This makes threats such as obstacles, terrain and any other shenanigans that takes place at lower levels a more serious consideration. Wire strikes are simply one of the symptoms of low level operations and off airport landings!

Lack of Planning Information

The other unfortunate nature of helicopter operations is that in many of the areas that they operate in, proper planning information is often not available. Jeppeson plates? Nope. Accurate charts? Nope. Local METAR and TAF facilities? Nope.

This all contributes to a less than complete picture of what to expect during flight. Making it more common for helicopter pilots to go to plan B, or deal with unforeseen circumstances. This often comes in the form of (temporarily) lowering cruising altitude, getting closer to those wires!

Wires are Hard to Detect

The next thing on the list is especially true for night operations on night vision goggles (NVG), but definitely still applies to daylight flights as well. Whichever way you spin it, wires are hard to spot.

During the day, they can blend into the background, especially if the background is pale / beige / colourless. During the night, NVG’s really struggle to pick up wires as well. Depending on the lighting conditions, the diameter of the wires, and how close you are to them.

There are usually two scenarios:

1) The flight crew is aware of the location of the wires based on planning information or masts, but they still cannot physically detect the wires.

2) The flight crew is not aware of location of the wires, and at the same time also did not manage to spot them

Distractions

Many accident reports with wire strike as the root cause, have some sort of lead up to the reason why the wires were not spotted. Often, even if the pilot was aware of the location of the wires en-route or around the ad-hoc landing site.

Distractions present themselves in all sorts of ways. However, they’re usually caused by external variables that were either not briefed, not expected, or not planned for.

Lack of a Thorough Recce

For wire strikes during the approach phase, the recce is the fundamental mitigation for this. Time pressure, lack of training, and complacency can all make a recce less thorough than it should be.

Especially at night, skipped or rushed recce’s can be a huge risk factor for wire strikes. Take your time, don’t skip the checks, and make sure your entire crew has the same mental map of what the landing site looks like before commencing the approach.

Poor Crew Coordination and Training

For multipilot operations, utilising the resources a pilot monitoring (PM) offers can be the difference between landing safely, and creating an incident or accident.

Lack of standard calls, go around procedures, or height and altitude call outs can result in an unstable approach. This can lead to a lot of mental capacity being spent on flying the approach, rather than maintaining overall awareness of the environment around you.

Not having a go around option is another red flag. If it isn’t clear between the crew what will happen if someone calls go-around, it will not only make that decision harder to make, it will also cause more uncertainty once someone does call off the approach!

Poor Lighting Conditions and Visibility

As discussed earlier, wires can be very hard to spot. Whether it’s a bright afternoon, dusk, or midnight: wires are sneaky.

There is also the notorious moments in the day where flipping down your NVG’s can make things worse instead of better. It’s too dark for the naked eye, but too bright for NVG’s to be effective: another red flag for wire strikes!

As mentioned by Paolo in our resources section below, wires can be significantly harder to detect in the mountainous areas, where visibility can reduce drastically in short periods of time.

How can Helicopter Pilots Prevent Wire Strikes?

There are many mitigations we can use to make sure we don’t end up as a wire strike statistic. Let’s go over the top 10 most effective principles you can adopt as a pilot to prevent a wire strike!

1) Follow Standard Operating Procedures (SOP)

SOP’s are one of the best examples of the fact that we’re standing on the shoulders of giants in our industry. Something goes wrong? Here’s a new procedure. Fatal accident? Don’t do x and y anymore, do a or b instead.

The aviation industry is still making a conscious effort to learn and adapt. Usually these ‘adaptions’ take shape in the form of regulations, new technology, and company SOP’s.

Things like recce’s, stabilised approach calls, go around briefings, and NVG procedures are all mitigations against wire strikes. While some might be annoying depending on the situation, try to make a conscious effort to implement them properly. Especially if you’re working together with others who rely on them as well.

As with most threats in aviation, avoidance is usually better than finding a solution. This is true even for helicopters equipped with a Wire Strike Protection System (WSPS).

2) Use Map Overlays

Use all the resources you can to build a mental map of your operating environment. A huge tool for this is (moving) maps, and the overlays that work with them.

Knowing or expecting wires make spotting them 10 times easier to do, as you’ll know where to look. It’s a strange feeling to look at an area that you KNOW has wires, yet you’re still not able to see them.

If you find yourself in this situation, either avoid that area completely, or don’t continue until you’ve made visual contact.

While there are many technical systems that can detect wires nowadays like the ones mentioned by the FAA, very few helicopters are actually equipped with them.

3) Proper Pre-Flight Briefings

A pre-flight briefing should include threats during take-off, cruise, and approach. While the wire overlays discussed above can aid during flight, it should also be referenced before even entering the flight deck.

Knowing what to expect is such valuable knowledge when the threat itself is hard to detect. Make sure the entire crew has a shared mental model of what the area you’re about to operate in looks like, so everyone is aligned with what to look out for.

4) Assume The Existence of Wires

During the assessment of a landing site, it’s better to assume that there ARE wires, than to conclude after one glance that ‘nothing is apparent’.

If you assume there are going to be wires, you’ll actually develop a much better scanning technique. It’s very common for crew to only detect wires because they were expecting them to be there – all thanks to a thorough planning phase.

If you see a mast, you know the likelihood of wires has increased even more. It’s good practice and use of Threat Error Management to plan the approach so that you’re still guaranteeing some sort of separation from that general area. This is even more true for areas where masts are planted in a line, but you can’t visually identify the wires themselves.

5) A Thorough Recce

Of course, the most straight forward antidote to wire strikes in general is a thorough recce. It’s still the most effective way to detect and avoid wires, despite onboard systems like terrain awareness systems and wire detectors.

6) Avoid Flying Low Without a Reason

Yes, flying low – especially in the military – can be a required action. However, if you don’t have to: don’t! Helicopters don’t tend to crash at 4000 feet under IFR. They do tend to however at 500’ under VFR.

You might have an ex military background for instance, and find that 500’ is your comfort zone. That’s great, but keep in mind that if there’s no reasonable argument to actually fly that low, you really shouldn’t unless there is an operational requirement that justifies it.

Drones, wires, kites, trees, terrain, valleys and many other variables are all much less of an issue the higher you go. Sure, you could argue it’s more time consuming to climb when you deem it unnecessary, but as long as you’ve made the assessment and you’ve covered your options.

7) Maximise Crew Coordination

In a multi-crew environment, the Pilot Flying (PF) should focus on actually flying the aircraft while the Pilot Monitoring (PM), well, monitors! This goes further than just flight parameters and aircraft systems.

Especially in bigger aircraft, part of the environment outside that is on the opposite side of where the PF sits, can be really hard to crosscheck. You become reliant on the other pilot to make sure clearances and any other unexpected threats are detected and called out.

As we will cover in a future article, it’s up to the captain to make sure the gradient in the cockpit is such that the first officer never feels like he can’t speak up. Plenty of fully serviceable planes and helicopters have crashed because of this issue, and it is also very relevant for the avoidance of wire strikes.

8) Identify the Masts

Yep, wires are hard to detect but masts are not! You can save a significant amount of time by prioritising the detection of masts rather than the wires themselves. The only sneaky trap with this is that some wires come from an area where you can’t see the masts easily, like in mountainous areas.

The quickest way to detect wires, depending on your available resources is:

1) Use the wire overlay on your Electronic Flight Bag (if available)
2) Use that information to spot the masts in the general area
3) Identify wires between the masts

Knowing where to start your scan and where to look in general saves a lot of time, and can make visually identifying wires much easier than going in ‘blind’!

Masts are not only handy for identification, but they are also a good aiming point for both the approach and the take-off (provided you can clear them), as wires are always lower than the masts!

9) Be Mindful of Complacency

Here’s the cold hard truth: a lot of pilots get very very used to their operation, the area they fly in, the helicopter they fly, and the crew they’re flying with. While that’s obviously a good thing in lots of diffrent ways, the main threat here is complacency.

Ask yourself if you’re walking the trail from vigilance to complacency, like we recently talked about here!

Complacency makes us lazy and, in general, downplay the threats we face every day. Wires are part of this, and should be actively mitigated for!

10) Brief the Go-Around Options

Just like with flying in general: having a plan B is crucial! Constantly asking the ‘what if’s’ keeps us alive. The approach phase is no different, what if it doesn’t work out the way you had planned? Where is the go around area, will you have to make a turn, where is the cut off point? Is the other pilots aware of your plan B?

If you’re flying single pilot, with or without a Technical Crew Member, all of these are still just as important to brief, even if it’s just for your own planning purposes.

Recent Wire Strike Accidents

These are the most recent wire strikes across the globe:

Air Ambulance Night Wirestrike at Poorly Chosen Landing Site

Wire Strike on Unfamiliar Approach Direction to a Familiar Site

Fatal Wire Strike When Robinson R44 Repositions to Refuel

Firefighting Helicopter Wire Strike

Fatal Wire Strike on Take Off from Communications Site

Wire Strike Resources

EASA on wire strikes

Conclusion

Wire strikes continue to pose a significant threat to helicopter safety, as indicated by the not-so-great accident statistics and recurring recent accidents.

If we as pilots are aware of the main causes of wire strikes, we can make an active effort to not become part of the statistics ourselves!

Have you got a story about your own experience with wires? Let us know, so others can learn from it as well!

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