Don't prod this particular hornet's nest

The RAF Regiment's job in Afghanistan is to protect Kandahar Airfield and the 13,000 international troops based there.

Situated just 15 miles (24km) away from the city, Kandahar Airfield (KAF), home to around 13,000 personnel, is huge. You can't miss it. The night I was in town an insurgent certainly didn't, firing a rocket into the base which landed 'somewhere near the helicopters'.

The bad guy probably regretted prodding this particular hornet's nest, as his one rocket in was repaid with ten mortars returned in 18 seconds.

Such protection is provided by the RAF Regiment operating as a NATO asset.

Flight Lieutenant Dale White, the Second-in-Command, described the patch the guys (150 of them) were controlling:

"Reaching out beyond KAF, we patrol 500 square kilometres, and we can call on extra assets to saturate that area if we have to. But building up a good relationship with the locals is a paramount task, which pays off.

Mortar-fying

In a remote corner of the base, a long and bumpy car journey away, is one of the mortar sites protecting the airfield.

The mortar crews live in a small compound just a few metres away from their 81mm mortars.

Communications and Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR) links are in a small bunker down some wooden steps. Billets are portacabins and food can mean surviving for eight days straight on ration packs. During quiet periods, one of them drives to the base to bring back takeaways of 'mystery meat and rice'. Leisure facilities are a few dusty weights baking in the heat. Mortar crews are a tough lot.

Sergeant David Hardy is in charge of this one:

"Basic mortar technology hasn't changed much over the years," he said.

Aiming relies on lining up spirit levels to within 2mm. Within a minute the team can shift the direction of fire 180 degrees with total accuracy.

Calculating the elevation and range to the target is now computerised, but if you want the missile to go further, you just slip another collar of gunpowder round its base. When the mortar fires, it punches the ground with a ton of pressure per square inch. The missiles are effective up to 5,675 metres with an accuracy of 15 metres:

"The mortars have a 40-metre killing radius. That's easily good enough to spoil the bad guy's day. If he's got another rocket on the rail ready to fire at us, the blast will knock the rocket off the rail," said Sgt Hardy.

"Often the sound of a round going off is enough to get suspicious characters to scarper."

The mortar crew have a new toy called the infra-red (IR) round. Once fired, it explodes in the night sky and produces the equivalent of a million candles' worth of light but you wouldn't know it:

"An IR round looks like a little star to the naked eye, but if you use night-vision goggles the place is lit up like daylight for around 400 metres of the shell burst, which can be over a kilometre away," said Sgt Hardy.