HEMS, or for those who dislike acronyms, the Helicopter Emergency Medical Service, is London's air ambulance. It is based at the Royal London Hospital in Whitechapel, and acts as a rapid response emergency service (also called the London Air Ambulance) to any accidents that occur within the Greater London and M25 areas. Painted a bright red, it is a godsend in a capital full of congested roads. The maximum time between receiving a trauma call and landing the helicopter near the scene of the accident is around 15 minutes. This includes the two minutes that it takes to get into the air, and the two minutes taken for the pilot to choose a suitable landing area. Most calls are reached within 10 minutes.

The crew consists of a helicopter pilot and co-pilot, a senior doctor trained in trauma care, a paramedic, and an observer; usually a doctor receiving training in pre-hospital care. It is equipped to be able to carry and monitor two patients at any one time. The presence on staff of a fully trained specialist trauma doctor is unique in the United Kingdom. The ability to carry such a resource to the scene of an accident buys those who are in need of emergency medical treatment valuable treatment time, the so-called 'golden hour' immediately after an accident where the chances of survival are highest.

It was first introduced in 1989, and has been based at the Royal London Hospital since the 30th August 1990. Since then it has flown over 14,500 missions across the capital. The Civil Aviation Authority has granted the Helicopter permission to land anywhere that the Captain of the Helicopter feels appropriate, but only if they have been called out to give urgent, life-saving treatment. There are not many Londoners who haven't seen it in action at some point; I myself can count three times in the past five years. Once in Stratford, after a stabbing. Once in Camden, after a pedestrian vs. vehicle. Once at London Bridge, again after a pedestrian vs. vehicle. The spectacle of the red Helicopter making its landing on a road in central London, surrounded by tall buildings, is truly a sight to be seen. I'd like to think the crowds that gather round at these times are doing so because of this spectacular display of flightmanship. However, I know in my heart that it's due to the natural instinct in all of us to rubberneck when someone's life hangs delicately in the balance.

The helicopter its self is an MD Explorer, developed by McDonnell Douglas Helicopters, which incorporates the unique NOTAR (NO TAil Rotor) system. The benefits of this are lower noise levels, increased performance and controllability, and, important in London's urbanised areas, increased safety.

The service runs from 07:00 hours till sunset, and is staffed by at least two teams of doctors and paramedics at any one time. After sunset, the service continues, but because of reduced visibility, the helicopter itself is not used. Instead, the teams use a set of rapid response cars (Subaru Imprezas, for those who are interested) to attend to scenes.

It's not the cheapest of services to run. Each mission costs around £700 to fly, and there can be many, many missions in a day. Half of the helicopter lease is sponsored by Virgin (hence its red colour), and as much funding as possible is provided by the NHS. However, it still has a shortfall of around £750,000 a year that has to be raised by donations from the public. Funds are raised in a variety of ways, including a lottery; the sale of HEMS logo-ed clothing and other items; and the generosity of those who are able to give as much as they can afford to the service.

HEMS played a vital role in the response to the recent tragedy in London. In all, medical teams comprising 32 personnel were dispatched, via both helicopter and rapid response vehicles, to the scenes at Aldgate, King's Cross, Tavistock Square and Paddington. The use of air ambulances from Essex, Kent, Lincs and Notts were also drafted in. It's not often that I ask things like this of people. But to all the Londoners who read this, I'd like you to think about the amazing response of emergency services to the London bombings. Then visit the HEMS website. And then after this, if you feel that you should, dig as deep into your pockets as you can afford and help keep this valuable service running. I feel horribly cheesy saying that the next accident it attends could be yours, or a member of your family's, or one of your friends, but in all truth, it might be. However small the chances are, accidents happen. This service is a true lifeline. Please be generous and ensure that it can keep flying in the capital.

And for those who don't live in London, please don't feel it excludes you from helping out a worthy cause.

Thank-you.

HEMS website – http://www.hems-london.org.uk/