from what height can a human fall and have a 50 percent chance of
survival? (assuming the person doesn't hit their head and they're
falling onto concrete.)

---

Request for Question Clarification by redhoss-ga on 23 May 2004 06:30 PDT

I saw your question when it was first posted. I thought that it was
interesting and looked at some information about "free fall" and
"terminal velocity". I suspect that the reason your question remains
unanswered is that you ask for an exact 50% chance of survival. I can
give you some very interesting information, but doubt that there is
any source that will answer the 50% requirement. Would you accept as
an answer the info I have found. I believe it will satisfy your
curiosity.

---

Clarification of Question by hannahi-ga on 23 May 2004 18:49 PDT

what if we put the question like this: how likely it is that a person
would die if they fell from a height of 30 feet? (still assuming the
person doesn't hit their head and falls onto concrete.) if this
doesn't help, we'd be interested to hear the answer you've found.

---

Clarification of Question by hannahi-ga on 23 May 2004 18:50 PDT

p.s. there is a bet staked on the answer. a slice of pizza.

Hello hannahi, I hope that you bet that a person will likely not
survive a fall from 30 feet. I have two references that would make me
believe that 30 feet is around the cutoff point for survival.

http://www.greenharbor.com/fffolder/ffresearch.html
The Free Fall Research Page

I recommend that you read this entire website. It has some incredible
stories about people falling from tremendous heights and surviving.
However, in an article titled "Unplanned Freefall? Some Survival
Tips", David Carkeet (an expert on free fall) says the following:

"Thirty feet is the cutoff for fatality in a fall. That is, most who
fall from thirty feet or higher die. Thirty feet! It's nothing! Pity
the poor sod who falls from such a "height." What kind of planning
time does he have?"

I also found this refererence to a medical abstract:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=96151877

There are few references discussing the typical injury patterns of
adults after a fall from a height. We present the pattern of injury in
101 adult patients who were treated between 1987 and 1990 at our
trauma center after falling from an average height of 7.2 m. In 62
patients the fall was accidental; 39 patients tried to commit suicide
by jumping from a height. The most common injuries were fractures of
the thoracic and lumbar spine (83.0%) with a preference for the
thoracolumbar junction. Fracture of the lower limbs occurred in 45%.
The most frequent injuries were fractures of the os calcis (64.4%) and
the ankle joint (26.6%). Twenty-five percent of all patients suffered
from fractures in the upper limbs with a preference for the distal
radius (56.6%) and the elbow (44.0%). There were no differences
between the injury patterns after a fall from a height of more than 7
m or less than 7 m. The incidence of thoracic and pelvic injuries
(30.0%) increased after falls from more than 7 m. The neurological
complications of injuries to the spine corresponded to increasing
height. According to our analysis blunt abdominal trauma is an
uncommon injury after falling from a great height. Head injuries,
which would be expected to be the most common cause of death in all
non-survivors in the literature, only occurred in 27% of our patients
who all survived their transport to hospital.

Of course 7.2 meters x  3.28 = 23.6 feet. That extra 6.4 feet makes a
lot of difference I guess.

Here is a very interesting website about people who have jumped from
the Golden Gate Bridge:

http://216.239.51.104/search?q=cache:SfERjaaV9pMJ:www.tamhigh.org/pubLibrary/teachers/lapp/PDF/5%2520Freefall.pdf+freeFall+survivors+height&hl=en

Since the Golden Gate Bridge opened in 1937, it has been used by over
1,000 people to end their lives. However, 1% of those who make the 22
- story drop are survivors. Those few survivors have air resistance to
thank for their new lease on life .The air resistance caused by the
earth's atmosphere assures that no one can ever experience true
freefall.

Also in .pdf document:
www.tamhigh.org/pubLibrary/teachers/ lapp/PDF/5%20Freefall.pdf 

I hope this is enough to win (or lose) you a slice of pizza.

Redhoss

There have been some limited studies conducted on the survival rates
of primates who fell from various heights but the only study I know of
that is even remotely similar to the one you require was done with
cats. The science of falling cats (and yes there actually "is" one) is
called "Feline Pesematology".

Regards;
tutuzdad-ga

I don't think air resistance is a significant factor in the survival
of jumpers from the Golden Gate Bridge.  With no air resistance, a
person would hit the water at about 80 mph, which is still much slower
than the terminal velocity of a human in air.  I think the survivors
lived because of the way in which they hit the water.  Belly-flopping
would probably kill you instantly, but if you entered the water
vertically, feet first, I think you'd have a much better chance.