PC Paul Cole, 30, air observer, Metropolitan Police Air Support Unit

“The Met helicopter base covers all London. We can reach parts of the city within three minutes while the farthest is about 15 minutes away. We work 12-hour shifts for four days or nights in a row.

“The Air Support Unit helps ground police officers to search for suspects or missing people. Rivers or railway tracks are dangerous places for ordinary officers to go, but in a helicopter we can follow someone across rooftops, even in the pitch darkness, by using thermal imaging cameras.

“The best part of the job is vehicle pursuits – car chases. If a car refuses to stop for police, a police helicopter is assigned as soon as possible. From the air we coordinate with officers on the ground and tell them the direction the vehicle’s going. It’s intense. We aim to stop the pursuit by telling traffic officers when to use the ‘stinger’ – the hollow spiked stop sticks that deflate tyres slowly so that the driver does not lose control but reduces speed to be less of a danger to the public. It can be difficult in London streets.

“We do lots of aerial photography. Crime scene photography can provide evidence for courts. We take pictures of iconic premises in London, such as the London Eye, so that planning officers have aerial footage in case of a major incident. We also carry out public order monitoring at carnivals and hover over political demonstrations in Parliament Square, downlinking a live video feed to headquarters.

“There are three of us in the helicopter, a pilot and two officers. We alternate roles: one is the front observer, the other is in charge of making decisions. He or she speaks on the radio and does stills photography on a harness from the open door. The camera operator controls the thermal and video cameras mounted on the skids.

“At the start of the shift we get the aircraft ready while the pilot and engineers check it over. We prepare the cameras and brief on preplanned jobs. All the footage is needed for evidence or planning so when we return we produce photographs, transfer footage to DVD and compile paperwork.

“Night duty is almost always reactive, searching for suspects or vulnerable missing persons. We can search a park in about ten minutes when it would take 20 officers all night. We carry first aid kits but in most cases it is more useful for us to stay airborne. London is so congested that it is difficult to land. The worst part is the limitations of weather – it can be very frustrating when jobscome in and you can’t fly.”

A second opinion

PC Tom Kingston, 33, tactical firearms officer, Hampshire Constabulary

“I start work at 7am and by 9am I could be sitting on an industrial estate doing surveillance, carrying out raids on addresses or walking around an airport on antiterrorist patrols. We provide an overtly armed presence, also guarding testing stations for large jets, oil refineries and dockyards – strategic sites that could be at risk from terrorist attacks.

“The tactical unit tends to deal with preplanned firearms incidents and high-end incidents rather than spontaneous events. We’re trained in dynamic interventions, such as hostage rescue. If everything’s gone wrong, then we turn up. If someone was dragged into a car by a person with a gun, for example.

“We don’t carry guns all the time but if we’re out we have access to firearms locked in armouries within a vehicle. A lot of the time we’re not armed – we’re out in plain clothes. We help the operational command unit on jobs: raids on drug dealers or surveillance. They call us because we are more experienced at dealing with confrontation. Our jobs can end with a “high threat” stop – the arrest of dangerous criminals, guns being pointed – that the average police officer wouldn’t do. The last time someone was shot in Hampshire was 1984. We don’t want to be in a position where we have to use a gun. Armed criminals usually carry handguns, but it could be swords or machetes. We carry arms as a deterrent and make up less than 1 per cent of the constabulary. It’s a huge responsibility. You may have to make a split-second decision that barristers and judges will spend months analysing.

“My work is unpredictable; I might have to go to an incident at 4.30am. We work off pagers so we’re subject to calls. It can be hard on the family. We do training to keep our skills up. We also do fitness training every day. I like the variety and the fact that there’s not too much paperwork. Firearms is physically draining and mentally shattering, but a great challenge.”

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