This article is a reminder of how the safety regulations for motor sport do matter, and are the difference between life and death under extreme circumstances. If you drive a car and don't check your equipment after reading this, you've missed the point.

I have been medical officer and then Chief Medical Officer for the M.G. Car Club meeting at Silverstone for some years now, so when I heard the "chequered flag" over the radio from race control for the last race of the Sunday meeting, I sighed with relief and sent my son, James, away to sit in the car. I would be out soon, and it was a tight schedule to get to the NEC, Birmingham, for 7.30. It had been another long boring day, with minor injuries and headaches, that sort of thing. Indeed, in about 2000 race starts at Silverstone in M.G. Car Club meetings in the last 9 years, there had been no significant driver injury.

I was sorting out the paperwork in the medical centre a few seconds later when the scramble call arrived, and James saw me disappear without a word in a green flash. We stopped at Brooklands and got clearance to enter the circuit while cars were still at speed, and then radio silence was called from Race Control to clear the air for a serious incident - which makes Silverstone seriously spooky when you are used to listening to circuit radio, calls from marshals, cars being snatched and so on. Just a little hiss from the radio as the medical car leans around Luffield. We passed some cars on the grass but no injuries, and then on the exit of Woodcote, half way along the start grid, is the other medical car, the rescue unit and a cluster of people around a wreck.

The intensity of the moment as you arrive at such a scene is hard to describe. Especially if you are responsible. There is a heartsink and fear that there is something will happen over which you will have no control. I am always scared that someone will die and I can't help. A wheel is detached from the car, the tyre unmarked but the alloy bent right out of shape. There is hardly anyone in the grandstand. The drivers face is rather blue, his helmet half off and the anaesthetist, Emmett, is cradling his neck and airway. You notice irrelevant details, such as the shredding of the fibreglass front end or the car where it has been torn. The chest moves normally as the driver breathes and I can't feel any injury, so haemothorax is unlikely. I do not fancy putting in a chest drain on the trackside, however many times I've done it before in hospital. The abdomen is soft and there is no mass over the spleen. By now we have a pulse of 140 and oxygen saturation of 96%. Emmett is clearing some blood away from the mouth with suction, but the airway is safe. The pulse is still strong. We can relax a bit as there seems no desperate problem apart from the head and neck, so we can concentrate on getting him out of the car slowly and without risking any injury to his neck or back. As he cannot speak to us, we must treat as though there is a spinal injury.

We slow down and take it carefully, and the team is co-ordinated by myself and we pool all our skills, especially the paramedics who are experienced in extrication. There is a chance to look around more, but all I really see is the RAC steward with a notebook, writing down what we are doing. The deliberation at this stage appears painfully slow to outsiders. Why are they not doing it faster? But it is hard to get someone out of a car under these circumstances. Space is more cramped than you expect, overalls get snagged in the footwell, and so on. Pulling him out too fast would only cause injury. The paramedics are very experienced at extrication and work to position a backboard, and, of course, a neck brace is already on. The cutters snip off the steering column, and then the roll cage. Out he came, and I nipped back quickly to the medical centre by car as the other two doctors came in the ambulance. The nurses in the centre have cleared out anyone with cuts and bruises, and the bed in the resuscitation area was ready with chest drain kit, oxygen, cardiac monitoring and so on all to hand. I brief them on what to expect.

We decide not to move him off the ambulance trolley, as he will be going to hospital soon He is starting to wake up, and is rather restless. It was good that he was partially awake and answering some questions, but when he started intermittently thrashing around from cerebral irritation it made us feel we had less control. We checked the pulse and oximetry a third time, and they were getting even better. Chest, abdomen, arm and leg examination confirm no serious injuries, so it is best to get him in the ambulance and off to Northampton General Hospital as soon as possible. I telephone the hospital, warning them what to expect. Then a telephone call to his wife and talk to his friends, sort out the paperwork and report to Race Control. Finally, my bemused son was still in the car! More telephone calls and a dash to the NEC just in time for my daughter's trip to All Saints. We just missed a rather poor backing band but were in time for the main act. By the way chaps, they may not look too bad, but they can't sing.

Before I left Silverstone, Race Control showed me the video of Russ's crash - by now I knew his name. He had been overtaking round the outside of another driver, both taking a fairly tight line because of a third car. There was contact and Russ went right over into the concrete wall, with no chance to slow down. He hit the concrete at just too acute an angle to bounce off along the track, so the car just crumpled a little and came back a couple of yards. The remarkable feature was the close up of the cockpit area. The car stopped so abruptly that the deceleration forces were clearly incredible. The harness stretched right out, so that his chest hit the steering wheel, and his head flew forwards but did not hit any fixed object. Debris missed him entirely, but anyone sitting on the left hand side of the car would have risked crush and penetrating injuries at chest, neck and head level. As I watched the impact over and again, the enormity of the forces experienced by Russ's body became more and more apparent.

Russ is an example of the effects of pure deceleration forces that were marginally sublethal. I refer to my copy of "The Pathology of Violent Injury" here. The G forces (multiples of the force of gravity) experienced during this type of event are calculated by G = 0.0039v2/d, where v is the speed in km/h and d is the distance over which the deceleration occurs, in metres. The MGB did not deform much during the abrupt hC deceleration - this saved his legs from external crush, but the lack of crumple increased the forces on Russ because the distance over which deceleration occurred was shorter Let's say the speed was 120 km/h and the M.G. had 0.75 metre of crush as it stopped, both I think reasonable estimates (Russ estimated his speed rather faster, I think, at about 140 km/h, but we'll be more conservative here). Therefore the deceleration was just under 75G. This represents a potentially fatal injury - at much over 60G, either the heart ruptures or the aorta falls off the heart. Russ's feet were up against the footwell and decelerated at the same rate as the rest of the car, and indeed Russ has fractures of bones in one foot. Recall, the footwell was not deformed and there was no intrusion . It was purely the force of the weight of his foot against the footwell that caused the fractures. If Russ's body had decelerated at this rate, he would have died from multiple injuries. Why was he saved?

The harness, you remember, stretched out forwards so that his torso moved over some distance - perhaps a bit too far as the steering wheel was bent, but the deceleration was spread over almost another metre. This gets the deceleration down to below 40G, which is survivable for the human torso. Then his head - this flew forwards another half a metre, so that the G was force was down to under 20G. However, the stretch on the neck must have transiently been much greater than this, as the neck would offer little resistance to forward movement until it got right forward. If the terminal deceleration on the neck was about 25G, then the force on the neck was twenty five times the weight of the head plus the helmet. This injury, I think, made Russ unconscious. The top of his brain was squashed against the inside of his skull and his brain stem, lower down, was stretched. All this occurred momentarily before the whiplash. You can see why the brain gets scrambled, even if it swims around in a little pool of cerebrospinal fluid, cushioning impacts. It is likely that some of the nerve-to-nerve contacts (synapses) rupture or are disrupted during the impact, and the severity and extent of this disruption determine the extent of brain injury. The brain can look normal to the naked eye, but becomes unwired. Russ was unconscious for about 10 minutes, not so bad as some other well known drivers - Mika Hakkinen had a much worse brain injury in Australia in 1985, but, as with Russ, there seems to be no lasting cerebral injury.

Russ's survival in this impact was down to perhaps the most mundane article of safety, which most of us take for granted. The safety harness is a brilliantly engineered piece of kit that converts a lethal injury into graded deceleration and survivable impact. So make sure your harness is not old and has not been stretched in an accident before - they don't stretch twice. Make sure your mounting points are secure - if Russ decelerated at 25G and it was probably greater, the shoulder mounts would have taken a force of over half a ton each. Indeed, examination of Russ's car apparently showed the metal around these mounts was deformed, but had not given way. Russ commented to me that in his MGA, the mounting points would probably have given way - so think about strengthening your harness mounting points, and spreading the load area. When you buy a helmet, get one that is strong and light - a heavy helmet can be bad news, so invest well. Make sure your seat is firmly attached to the floor - you don't want that on your back.

Lastly, if you have a six point harness, do arrange the crotch straps carefully when you strap yourself in. If your pelvis weighs 20kg and you decelerate at 25G, you've dropped half a ton in the area of your testicles, so your eyes might water.

Yes, this accident looked a little like that sustained by Michael Schumacher, and the rescue team followed exactly the same types of procedure (I was not at Silverstone for the Grand Prix). But the Ferrari hit the concrete at 100 km/h, apparently , and the deceleration was not enough to make Schumacher lose consciousness. Russ hit the wall harder, and was fortunate enough to have a car that, in this type of impact, looked just as strong. Amazing little cars, M.G.s, aren't they?

Thanks to the team The paramedic, rescue, marshalling nursing teams and everyone else involved at Silverstone were wonderful; their experience and training made the rescue effective, controlled and state of the art. Although I was Chief Medical Officer, I had to do virtually nothing, the entire team worked like clockwork and they must take the credit. I do not think they could have been better, so if you are going to have a bump like Russ anywhere, Silverstone is the place Even better, drive safely and look after yourselves.