HELICOPTER TREEWORK 101
AN INTRODUCTION TO TREE REMOVAL VIA HELICOPTER.
First of all, with a grand total of ONE helicopter job under my belt; I’d like to state that I’m by no means an expert on this subject. That said, I hope we can still contribute to the arboricultural community by sharing this unforgettable experience.
So your boss rings you up and tells you he’s got a helicopter job lined up. Besides trying not to wet yourself in excitement - how should you [the climber] go about making sure you don’t mess up this incredible opportunity? Think of this article as part recipe for your mental toolkit & the rest as an epic picture/video fest of everything you’ve ever wanted to see a helicopter do!
WHO WANTS A CRANE WHEN YOU’VE GOT A HELICOPTER?
So in New Zealand, we are fortunate enough to have some fairly significant and well regarded legislation which the general public tend to take seriously. Specifically there is a great emphasis placed on not disturbing the ground on sites of unique cultural heritage to the Māori community, there is also extensive protection on areas of NZ native vegetation. You may not know this, but thanks to its status as an island nation, as much as 80% of the species of flora in NZ are endemic [not found anywhere else in the world].
Combine this legislative protection with helicopter aviation expertise often used in hunting & agriculture, and you have the perfect circumstances for tree removal via helicopter being the best choice. It helps that we’ve got some of the best climbers in the world here too.
YOU WILL NEED
- 1 x Helicopter [Squirrel AS350 SD2].
- 1 x Pilot [preferably with experience lifting trees].
- 25 x 2t lifting slings.
- 2 x Climbers [bring your balls].
- 2 x Ground workers.
- 2 x Dogmen/Banksmen.
- 2 x Midsize [70cc] chainsaws with a minimum of 20” bars - & don’t forget the Reecoil Big-Boss Chainsaw Lanyard.
- 4 x Wireless headset comms - PTT isn’t going to cut it, make sure you use the SENA style bluetooth units.
A good night's sleep followed by a big breakfast & plenty of fluids!
STEP 1 - ASSESS YOUR OPTIONS & DO YOUR RESEARCH
First you need to decide whether the tree warrants the use of a helicopter, with running costs in the thousands of dollars per hour - this isn’t a decision to be taken lightly. For us there was a very large declining pine tree [non-native] growing on the edge of some protected native bush. A house was being relocated from an adjacent site to site right underneath this tree. Understandably the tree couldn’t be left to overhang this property. We couldn’t disturb the vegetation in anyway & there was no way we could get a crane big enough close enough to the site.
I prepared a method statement for the council which detailed how we would go about the job. I also asked around several local arborists with more experience doing heli-work about what I needed to know as the climber. I have summarised this into the “Tips & Tricks” section of this post.
STEP 2 - PREPARE THE SITE
Next you need to make sure you have an appropriate drop zone for the helicopter, best to get the helicopter company involved at this point because they know what their machine can & can’t do. You also need to make sure they have a refueling site close enough nearby.
At this point the climbers involved should discuss their approach with the helicopter operator. With heli-work the costs are so high per hour that all of the sections of tree to be removed are “pre-slinged” so that the helicopter is never waiting. Find out what the helicopter is good to lift for, add in any safety factor you want to & then you have your intended lift weights. For us I was told the heli was good for 1200 kg maximum and so I aimed for each lift to be 750 kg. This process is identical to how you would go about using a crane, except that you sling your pieces in advance. Place your slings appropriately based on your estimates of how much you think each section weigh - it gets easy by the time you get down to stem wood, don’t underestimate the weight of foliage.
STEP 3 - LIFTING OUT THE TREE
The bit you’ve all been waiting for. For us the drop zone was so close that the turnaround time between lifts was less than a minute. This really puts some pressure on the climbers, prepare as much as you possibly can in advance, so much so that your saw should already be warm when the chopper arrives.
The big difference between heli & crane work is that its is a lot more dynamic. With a crane, you want to make everything as static as possible, to the extent that the aim is generally to make sure that the piece barely moves once you’ve cut it. With a helicopter, the pilot is able to move in more or less any direction necessary, consequently the aim is more to get each section to roll away from you once you’ve cut it. There are a lot of different cutting techniques you can employ, but the important bit is not to get the saw stuck! Cut the compression wood first, then the tension wood, ALWAYS make sure that you are in a safe position so that when the piece is cut it can instantly roll away from you. The pilot will do his best for you but don’t expect him to understand how trees behave better than you.
Even with two climbers you really have to hustle if you’re going to make it to the next cut in less than a minute. I couldn’t have achieved this without the following technique:
All you have to do is tie on a ring or connector which can be safely side loaded to the end of your climbing line, the throw it round the stem, poke a bight of rope through then clip the bight back on to your DdRT system. This is invaluable on big wood because you don’t need an irritatingly long cambium saver. Normally I climb exclusively on SRT but for rapid descent and instant retrievability, this is the best way.
STEP 4 - CLEAR-UP
If you have space then clearing up as you go is definitely preferable - you may need some serious chippers and mechanised loading to make this possible though. For us there wasn’t space so we had to make a huge mess and then clear up afterwards - not so much fun.
TIPS & TRICKS
- Do your research, don’t be afraid to ask questions, use everything you’ve learnt from crane work and make sure you’re confident on what the section will do once you’ve cut it.
- Put a brand new chain on the saw - don’t leave anything to chance.
- Half hitch the tail of each sling right above where you intend to do the cut - it keeps everything tidy and really helps you focus when the pressure is on.
- Make sure you cut the compression wood first - I tried to be in the centre of the tree and have each section roll away from me as I finished the cut.
- Make sure you have everything you need on you - there’s no time to go back down. Bring water in a hydration pack & attach your silky with a tool lanyard.
- Do all of the tops first if it is multi-stemmed - this gives the pilot more options for movement.
- Make sure your comms are all charged and fully operational - they’re essential.
- Think about your position when you finish the cut, because of the way the piece moves once cut, it may be necessary to hold the saw a little higher than you’re used to. I aimed for chest height so I can easily duck my head out of the way if the piece comes towards me.
SOME WELL DESERVED THANKS & CREDIT
- Dale Mills-Houghton [Waitakere Tree Services Director]. Well done for organising the whole job & convincing the client to use a helicopter!
- Loga Heperona Ofisa. I wouldn’t have wanted to be in the tree without you.
- Shaun Hardman [Hardfell Professional Arborists - Instagram Tag @hardfell_ltd]. Spot on advice with regards to sling technique and general “how to” from a climber’s perspective.
- Helisika Ltd [Instagram Tag @helisikanz] - particularly Hamish for his exceptional piloting.