Friday, June 23, 2017

Rappelling to get away from a high-rise fire?

I found an article over at FerFal's place, discussing rappelling (a.k.a. abseiling) as an escape technique from a fire in a high-rise building.  It's obviously prompted by the Grenfell tower fire in London earlier this month.  I visit Ferfal's blog regularly, and mostly like what he has to say;  but, in this case, I must respectfully disagree with his advice.

In the first place, here's what the tower looked like as it burned. Look at the flames spurting out of windows all around the building, and the burning insulation (cladding) around the concrete.

Now, imagine dropping a rappelling rope (usually of kernmantle design, made of nylon and/or other synthetic fibers that are flammable) down the side of that building.  What are your chances that the rope will not catch fire?  I'd say slim to none.  Even if it doesn't, what are your chances of rappelling down the side of the structure, safely and uninjured, with so many flames reaching out at you?  Again, I'd say slim to none.  Even if you start down a side of the building that isn't visibly on fire, what guarantee is there that it won't catch fire while you're on the way down?

There's also human nature.  If you're trapped in an apartment, and you suddenly see a rope dropped past your window or balcony, aren't you very likely to seize it and try to climb down it yourself?  Unfortunately, if you're not fit or strong enough, or adequately trained in rope climbing techniques, to take advantage of it, you're unlikely to reach safety by using it;  and, in the process, you're likely to overstress the rope's weight limit (remember, the person who dropped it will also be using it, higher up the building).  Put too much weight on the rope, and it'll probably snap.  Even if it doesn't, the point on the building to which it's anchored may not be able to take the added weight, and might give way.  I'd say many people trapped in a burning building will behave like that, making escape problematic, to say the least.

There's also the need, not just for training, but for ongoing familiarization.  Training in rappelling techniques is widely available, sure enough;  but like any specialized skill, it takes ongoing practice to remain useful.  If you learn how to rappel, but never practice it after that, how much good will that be in a building fire five years later?  Will you remember it well enough to get to the ground in safety?  More to the point, what about your kids?  You may have learned to rappel as a solo climber, or with your partner;  but if you now have one or two small children, have you ever practiced harnessing them to your body, so you can get them to safety as well?  I'd say the odds of that are vanishingly small.

Some (particularly after the 9/11 attacks) have spoken of using a parachute to escape a high-rise building.  They're available, but their use raises at least five issues.  The first is that parachutes, like rappelling, require training and ongoing practice to use effectively.  Next, there's the the proximity of other buildings.  If yours is in a cluster of them, such as a city center, there isn't going to be a lot of empty space for your jump.  The odds of colliding with another building, or getting your parachute caught on an obstruction like a protruding flagpole or fire escape, or hitting power lines or telephone wires on the way down, are pretty high.  Third, the wind in such an environment can be fluky.  It can vary in strength, direction, etc. as it's funneled between the buildings.  That's going to affect the behavior of your parachute.  So will the fourth issue;  updrafts caused by the heat of the fire.  They've been measured at over two thousand feet per minute - a nightmarish prospect.  Winds or updrafts may carry you back against - or even inside - the burning building from which you've just jumped.  Finally, parachutes, like climbing ropes, are made of synthetic materials.  They're not fireproof.  If you have to jump through or past flames to get off the building, and/or your parachute canopy happens to collide with a piece of burning debris, floating in the air (and there are usually a lot of them in a fire like that - just look at video clips to see them for yourself), it may catch fire.  If it does, you're going to drop like a stone.  On balance, I'd say that parachutes aren't a viable means of escape for anyone except trained, experienced sky-divers, and even they will have serious problems in such an environment.

On balance, I think the recommendations I gave in my first article on this tragedy still hold good.  Live as low in the building as you can arrange;  get out as fast as you can, as soon as the warning is received;  have flashlights, fire extinguishers, and other emergency equipment to hand, so that you can use them to aid in your escape;  and don't rely on emergency services to get you out.  They'll doubtless do their best . . . but they can't perform miracles.

At the time of writing, the death toll in the Grenfell fire stands at 79.  Many of them trusted 'official guidelines', and stayed put, waiting for a rescue that never came.  Don't make that mistake.



STxAR said...

I could see the use of zip lines, like the escape lines on the old oil derricks. I've worked on high rises in the past, and that seemed like the only viable way to escape. But how to deploy them? Best to stay on the ground!!!

shugyosha said...

I suspect flammability would be less of an issue than melting.

Take care


Tierlieb said...

It depends on your perspective. Rappelling is neither easy nor safe. But it beats trying to walk down the stairs. It is probably the best alternative of all the bad ones. Jumping out of the twin towers was a better decision than burning to death given the limited choices available. Same here.

That said, like with avoiding conflict instead of surviving it, the key to this is knowing when to leave. Once the fire has progressed so far that the insulation burns, chances are slim. "If you see smoke, you're already late; if you see fire, you're probably too late" to quote a firefighter friend of mine.

Regarding perishable skills: I get to train this once every year and I find this to be plenty. I consider it an easily learned skill and not too perishable -- except for the required knots used to control your descent. Those are easy to get wrong under stress when using a simple figure-8 as Ferfal's picture shows. There are many good mechanical descenders that make this less risky.

Regarding rope burning or melting: Yes, that could be a problem, even earlier you'd encounter the problem of reduced tensile strength due to heat. That should be a big problem with Spectra and Dyneema, and a small one with Kevlar.

As for someone else grabbing the rope: Have you ever tried catching a rope while someone is descending? Add to that the rather large safety margin of climbing ropes (again, Ferfal chose a rope with a comparatively small diameter) and I'd consider this an acceptable risk.

Randy said...

I don't know about weight limits on climbing ropes so I don't know if adding one of your lower floor neighbors would be a problem. But i can imagine one of those neighbors, after seeing you pass by their window on the way down, jumping on the rope since you appeared to be successfully making your escape. Most people, me included, don't know anything more about rappelling than what they learned by watching it on TV. If/when they fall, they will take you with them.

sysadmn said...

You raise valid points, but the weakest is the "someone else on the rope" claim.

Climbing ropes are overengineered to provide a safety factor (now called a design factor); typically a rope is rated for at least 5 times the working limit, and 12 times is recommended. So the problem of another person on the rope isn't the weight, it's their movement. On the other hand, knots significantly weaken a rope, and heat can also. The rope need not catch fire; if it's in 200-500° air it is much weaker.

Anonymous said...

Here's a company that makes a backpack/harness with up to 260' of steel cable and a controlled descent mechanism.

Anonymous said...

Interesting thoughts. A vendor came to our office this past Tuesday and had pictures of him using that Las Vegas Statosphere Tower Sky Jump, a ride that hooks you up with a harness and drops you down the side of the tower to the ground below. The maximum weight allowed (safety wise) is 265 pounds.

I wonder if tower evacuation could be done using this system. Some training and familiarization would be needed of course, but this has some possibilities.

Will said...

1) Never listen to authority figures in a building fire. They will NEVER have accurate info. They are automatically following the mental format that demands that they be in CONTROL. Have you ever dealt with a bureaucrat that was correct in all particulars?

No knots. You must use other means to slow your decent. If you are expecting to CLIMB down that line, you are a fool. Have proper gloves for everyone you expect to go with you, and have them attached in some manner near your anchoring point of the line, so they don't get lost. Have extras. Harnesses, if used, should also be located in a similar manner.

People who attempt to commandeer your line while it is in use by you will probably fall off at some point. This behooves you and your party to be quick in utilizing it. Those below you will probably be knocked off when you slide into their hands, as they attempt to climb down. Sucks to be them. Frankly, the odds of them grabbing a non-tethered line are slim. Once you and parties are moving down the line, it may be easier for them to access, but if you all are moving at a proper pace, there will not be much of a window for them to utilize.

Speaking of windows, most high rise windows are fixed, so hijackers will have to break them out to access your line. This is another reason for haste. Where do you think those glass shards will go, along with the object(s) used to accomplish this?

Will said...

Also, lock any doors that allow access to your line origin. You don't want people keeping you off your own line, or even just slowing down the process of bailing out. You could consider unlocking the door(s) by the last user, as long as there is no one trying to force their way in. Your call. High hazard potential, unfortunately.

I'm thinking the small diameter cable might be a good choice for this application.

Anonymous said...

I have rappelled, and own 200' and harness and attachments etc.
I have also kicked in a few doors over the years, and own a 16lb sledgehammer.
If the fire was below my unit-(Assuming fellow tenant was NOT home.) I'd have NO compunction about opening a door to a different view.
I'd happily take my chance of falling off a breaking rope- than sit tight and ROAST. THAT is ridiculous!

SURE-Obviously- some people can't Rappel~ those who could- should go sooner than later.
If you know how to do it- CERTAINLY easier than hoping for a rescue...
Your earlier article details are of course valid- but hey- closer to the ground- shorter rappel If it came to that!

But Yah--Glad I live in house:)

bmq215 said...

Yep, I'll echo everyone else in saying that climbing equipment is ridiculously over-engineered. Is it a sure thing? No. But any reasonably fit person with the knowledge and equipment would have a lot better chance of making it off the upper floors by rappelling than climbing down through the fire. I'm also not at all worried about someone latching onto the rope below me. Either they know what they're doing and will beat me down or they'll likely fall within seconds.

Does everyone have the knowledge, skills, or fitness to do this? No, and if worst comes to worst it sucks to be them. That's just how it works.