So there you are - trapped high up in a burning building, cornered at
a cliff side by generic baddies, or riding an explosives-laden train across a rickety bridge,
with only a precipitous drop as a means of escape. Mondays, amirite?
While it’s pretty obvious that falling from a great height is a fairly reliable way to
kick the proverbial bucket, in certain, extreme situations it might be preferable to take your
chances with fall damage rather than face an even greater and more immediate danger.
So, thinking about it, what sort of heights could
a person fall from and and have a reasonable chance of survival?
“You thinking what I’m thinking, partner?” “Aim for the bushes.”
I’m Stu, this is Debunked, and we’re here to sort the truths from the myths,
and the facts from the misconceptions.
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According to the World Health Organisation,
falls are the second most common cause of unintentional injury deaths worldwide,
behind only road traffic injury deaths.
Known more academically as ‘vertical deceleration injuries’,
the negative effects of falls are significant;
across the globe, there are an estimated 684,000 fatal falls every year. Indeed,
the U.S. workplace safety agency…
OSHA identifies falls from height as one of four main occupational hazards,
known ominously as the ‘Fatal Four’. Clearly,
falling from very high up can be very bad for your health.
To get started, let’s look at the physics of one of these ‘vertical deceleration injuries’,
to help us get an idea of what makes falling such a massive hazard.
At the most basic level, things - in this case,
people - fall to the ground because of the influence of Earth’s gravitational pull.
The height of a person’s fall determines the speed at which
they will be moving when they eventually stop.
The higher up you are when you fall, the faster you’ll be moving…
…when you hit the ground, and the harder you’ll hit. Simple.
However, this speed doesn’t just increase indefinitely the higher and higher you get;
since planet Earth has a gaseous atmosphere,
…an object falling through it experiences drag in the form of air resistance i.e. the
collective effect of billions and billions of air molecules slamming into you as you fall.
This acts as an opposing force to gravity, and as you accelerate under
the force of gravity, the amount of air resistance also increases,
until these forces eventually reach a point of balance. When this happens, you will have
hit your ‘terminal velocity’, and will no longer fall any faster under your own weight.
While this specific speed will vary slightly based on size, weight (yes weight), body position,
clothing etc., the average person reaches terminal velocity after falling for about 12 seconds,
at which point they’ll be moving at about 200 kilometers per hour
or roughly 120 miles per hour, and will have fallen approximately 450 meters.
This means that it doesn’t matter if you’ve fallen from 450 meters or 1,500
ft - when you hit the ground, you’ll do so at the same speed.
If you stop suddenly by hitting the ground while traveling at 200 kilometers per hour,
it’s fair to say your chances of survival are practically zero.
At the exact moment of impact,
…the surface of your body that makes contact with the ground immediately stops moving. For a
split second after that, however, all of the body mass above it… well, that keeps going.
This means the force of your own body weight slams down onto itself at 200 kilometers per hour,
bursting cells, ripping apart blood vessels, crushing bones and organs,
and just generally ripping body tissues apart and turning you into human mush. In short, ya dead.
Of course, most people who die in falling accidents do not do
so after plunging from the roof of a skyscraper,
…and certainly are not traveling at 200 kilometers an hour when they hit the ground.
Indeed, the Health and Safety Executive, the national health and safety regulator of the UK,
points out that most “fall from height” accidents…
…involve falls from things like roofs, large vehicles, scaffolding, overhead walkways,
…and especially ladders.
Think about that the next time you’re changing a lightbulb.
With this in mind, is there a height from which
it is generally agreed a fall would be fatal or survivable?
Well, although there has been a fairly considerable amount of investigation into
this very issue, it may surprise you to learn that individual studies and expert
opinions do vary in what they conclude to be a non-survivable fall height.
Investigations into how height affects the survivability of falls often employ the
concept of a ‘median lethal dose’ or ‘LD50’, an abbreviation of ‘lethal dose 50 percent’.
This metric is most widely used in toxicology for assessing the relative strength of poisons,
by measuring the amount of a substance needed to kill half of a tested population.
When used to evaluate the survivability of falls from height, however, ‘LD50’
refers to the median height at which 50% of fall victims do not survive.
So, what is that crucial height?
Multiple sources, including medical textbooks and scientific journals,
…state that someone who falls from 15 metres (or about 48 feet) up,
has a roughly 50/50 chance of survival.
However, this oft-cited statistic was established around the 1980s,
and a more recent study from 2017 suggested that medical advancements
since then have pushed the LD50 up closer to 20 meters, or around 68 feet. Good to know.
On the other hand, some studies are more pessimistic, reporting 50% and
100% mortality rates at heights of only up to 12 and 18 meters respectively.
Indeed, a 2019 study conducted in India found that over 90 percent of all fatal falls…
…happened at heights of up to 12 meters, or just under 40 feet.
Not only that, the study also found that almost half of all fatal falls
happen at heights of under 6 meters, or only about 20 feet.
Similarly, information from the U.S. Bureau of Labor Statistics show that in 2015,
16.9% of all fatal falls were from heights of 10 feet or less. That’s only 3 meters.
Of course, it’s likely that there will be variable conditions that influence the outcome of the fall,
such as environmental factors,
…the physical surroundings (like the average height of
the building you’re likely to fall from),
… and the general health of the victim will also play a significant role.
On top of that, there are the safety standards of the country where the fall takes place,
…as well as the quality of the area's healthcare to take into account.
So it’s perfectly possible - perhaps even likely - that the
average height of a fatal fall might very well vary from place to place.
But evidently, height is not the only factor here. As it turns out, falls and fall-related
injuries are governed by a very complicated array of physical and biological interactions,
of which the specific height of the fall is but one part of the equation.
While the survivability of a fall obviously does progressively dwindle the higher the fall is from,
it is not the only thing we have to consider.
Aside from height, one of the most significant variables…
that determines whether you’ll pull through or perish following a fall is the…
…position and orientation of your body upon impact. It should be obvious that
…you’re more likely to survive a 10 meter fall onto your feet…
than you are to survive a 5 meter fall directly onto your head.
While crumpled, broken legs are no doubt unpleasant,
injuries to one’s extremities are usually far less life-threatening…
…than injuries to the torso, head, and neck.
Not surprisingly, a recent study from 2022…
…found that injuries to the feet, ankles,
and pelvis are more common in those who survived falls,
…while head and chest injuries are more common…
…in those that didn’t.
Basically, it’s better your ankles take the hit than your fragile yet vital brain.
In 2011, the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine…
…reported on the extraordinary case of a woman who experienced a truly
nightmare-ish fall while climbing in Colorado’s Rocky Mountains.
At one point during the ascent, a safety rope slipped through her harness,
causing her to plunge down 60 meters,
where she smashed into a solid rock surface,
…before falling another 30 meters and again hitting solid rock
where she finally stopped,
for a total vertical fall distance of 90 meters, or roughly 300 feet.
Her boyfriend, who was on the climb with her and witnessed the entire fall,
immediately rushed down to find the woman terribly-injured, but awake.
Emergency services were immediately called,
…beginning a lengthy recovery period involving numerous surgeries.
After several months, the woman was essentially back to normal,
concluding an exceptional case of someone surviving a fall…
…that would generally be considered entirely unsurvivable.
Much of the academic discussion of the incident focused on the position and
orientation of her body upon impact, crediting her survival to landing feet
first. This spread the force of the impact over a longer period of time,
across a larger area, and concentrated much of the force on less essential body parts.
Another extremely important thing to consider regarding
the survivability of falls is the impact surface itself.
Newton’s second law, which states that the force experienced by an object is equal to
its mass multiplied by its acceleration, helps explain the significance of the impact surface.
The force your body experiences upon impact depends on your body's mass and
the acceleration (or deceleration) it undergoes.
Whether you land on soft grass or hard concrete, the change in velocity will be the same
i.e. the velocity of your fall before contact,
and the deceleration down to 0 as your body comes to a complete stop.
It’s this rate of deceleration to zero that is crucial to your chances of survival.
A deformable surface lengthens the period of time over which deceleration occurs,
reducing the force of the impact
If you think of it like a crumple zone in a car then it becomes clearer,
…the energy from your fall has to be transferred somewhere, and that means that it’s either
absorbed by the impact surface causing it to crumple or you absorb it, causing you to crumple.
Extending the deceleration even by only a few milliseconds,
can reduce the damage of a fall significantly.
Landing on surfaces like wet, mushy ground, or a thick covering of snow
is likely to be significantly less lethal than slamming into hard concrete.
Sometimes just having something to break your fall makes a crucial difference, and despite it being…
…a movie trope,
…it seems that every few months there’s news coverage about someone falling out of or off
of a high-rise building and surviving the ‘unsurvivable’ fall by landing on a car.
Most recorded stories involve survivors landing on parked vehicles,
…but in November 2014, in the financial district of San Francisco,
58 year old Pedro Perez lost his balance whilst on his window washing apparatus…
…11 storeys above the sidewalk, and plummeted nearly 40 meters or 130 ft…
…onto the roof of a moving car!
Miraculously Perez landed on the rear half of the car just behind
the driver’s seat. The driver escaped completely unharmed,
…while Pedro was immediately rushed to hospital. Though the injuries
that Perez sustained were substantial, and he could easily have been killed,
experts speculate that had the incident occurred a few seconds
later he would have missed the car and not survived the impact with the tarmac.
“...it took about three seconds for Perez, falling at an estimated speed of 60 mph [100 kph],
to hit the car, which acted as a big shock absorber and saved his life.”
From these stories, we can see that under exceptional circumstances,
when the conditions are just right, humans can potentially
survive falls from heights that are usually almost invariably fatal.
It’s insanely unlikely, but ‘insanely unlikely’ doesn’t mean ‘never happens’.
Statistical investigations into the death rate of falls have determined that falls from 15 meters,
or 48 feet, or roughly 4 or 5 floors up in a building, have a 50 percent survival rate;
that is to say, people who fall from that high up survive and do not survive at equal
rates. Mortality rates increase to 90% at the 22 to 26 meter, or 75 to 85 feet height range,
around the seventh floor. Falls from floors above the 7th quickly approach a 100% chance of death.
As mentioned, recent medical advancements may mean survival
rates could be better than previously indicated.
But the truth is, it isn’t really possible to pinpoint a
specific height at which a fall just immediately stops being survivable,
because the survivability of a fall depends on far more than just height alone.
Your chances of surviving a fall from height are multifactorial; height is a major determinant,
but so are body position, landing surface, the age and general health of the individual falling…
…even something like the clothes you are wearing can affect your chances of survival.
Of course, exceptions exist amongst even the most
serious of circumstances. If there are enough people falling off of things…
- and there are - some of them are going to defy the odds.
And so, if you are still trapped high up in a burning building, cornered at
a cliff side by generic baddies, or riding an explosives-laden train across a rickety bridge,
with only a precipitous drop as a means of escape, here’s the advice we have for you -
1. Aim
- if there is anything on the ground that would
provide a softer landing than concrete, aim for it.
2. Try to break your fall
- it’s a grim prospect, but any contact you can make with
anything on your way down will slow your fall when you eventually stop.
3. Attempt to land on your feet
- your lower extremities are your best defense against damage to your more vital organs.
4. Roll to the side
- lengthening the duration of the collision, even by a fraction of a second, can be crucial.
5. Be very, very lucky.
Bon voyage!
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Thanks for watching and we’ll see you next time