The odds of survival

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In recent weeks, three Kiwis have defied death after falling from great heights. So what does it take to survive a big fall? By Adam Dudding

IT'S FIVE years since trauma surgeon Grant Christey saw the Harbour Bridge jumper at Auckland Hospital, but he still has no trouble remembering the list of injuries.

Pelvic fracture, lacerated spleen, lacerated bowel, fractured liver, fractured ribs, bruised heart and lungs, spinal injuries, fractures to upper and lower limbs.

Incredibly, the would-be suicide, a man in his 30s, escaped major brain injury or paraplegia, and made a remarkable recovery. To the best of Christey's knowledge, he has gone on to live life "to the full".

Christey is all too familiar with the brutal effects on the body of a big fall onto an unforgiving surface, and the tough odds faced by the survivors of a remarkable string of falls in recent weeks.

Last month a 15-year-old boy who fell from the 16th floor of a Manukau apartment block survived because his fall was broken by the steel roof of the apartment carpark; earlier this month an 18-year-old woman fell six storeys from a central Auckland carpark building and lived. That same week, a council contractor survived a 40m fall down a sheer cliff face from the summit of Mt Maunganui.

Christey, now a trauma specialist at Waikato Hospital, says: "It's great to see stories of survival, but not all are that successful... if they'd fallen on concrete it would have been a different story."

He said a 3m fall is the threshold above which the body will "start to break when it hits something", and a fall greater than 10m is generally "more than your body can sustain".

Land on your feet, and you're looking at fractures to ankles, legs and the spine; land on your belly and you're likely to sustain massive injuries to the chest and internal organs.

People, unlike cats, aren't terribly good at reorienting themselves in the air, so you're unlikely to get much choice about which way you land – but in any case, the often fatal factor is head injury. And if you're moving fast enough, a head injury is likely whichever way you land.

The key to survival, says Christey, is landing on something that slows you down at the last second. Skydivers whose chutes fail can survive if they land in a tree, or a snowdrift, or a freshly ploughed field. (Water, curiously, isn't a good bet – a fall into water from more than 50m is seldom survivable, says Christey.)

Survivors of big falls from buildings have generally crashed through awnings or balconies on the way down, once again dissipating their vast kinetic energy over a longer period of time.

But whatever the physics, some survivals still appear little short of miraculous. Skydiver Michael Holmes fell 3675m over Taupo in 2007 when his parachute failed. His descent was slightly slowed by the malfunctioning chute but it is estimated he was still travelling at 128km/h when he smashed into a blackberry bush and left a body-shaped crater in the soil. He suffered a punctured lung and a broken ankle and spent 11 days in hospital.

Stunt co-ordinator Paul Shapcott says making staged falls safe depends on lengthening the period over which the faller decelerates – stretching it out by just milliseconds can make all the difference.

One method is to "wire work", where a stuntman or woman is tethered from above and is mechanically slowed in just the last few metres. Alternatively, the stunt actor lands on something that will partly give way and absorb their momentum: giant gym mats for short falls, or carefully constructed towers built from cardboard boxes for long falls.

If an accidental fall ends on an unforgiving surface, the body just can't cope, says Shapcott. "Everything that's moving wants to keep on moving but it can't – that's why everything gets broken."

How to fall fast – but land slow

Every second that a person is freefalling, their speed will increase by around 9.8 metres/second (that's 35km/h), until the increasing resistance of the air matches the gravity accelerating them – and they will reach "terminal velocity" (TV). For a person falling flat, that's about 190km/h (which they'll reach after 17sec of freefall). For someone taking a more streamlined shape it can be as high as 320km/h. Clothing, and the size of the person, will affect the terminal velocity too. Stunt performers seldom get near terminal velocity (except in skydiving stunts), as it involves falling more than 900m. Careful physics calculations are made before any stunt jump, taking into account the height of the fall, the weight of the stunt performer, their costume (something billowy will have more air resistance), whether the landing impact needs to be seen on camera, what objects there are to land on or fall through, and the final landing medium (earth, water, snow). Stunt performers also minimise the damage and pain of impact by spreading their weight over a greater surface area – that means landing on a mat spreadeagled, rather than in a tight ball. Rolling on landing can also reduce the damage.

- © Fairfax NZ News