In an emergency call-out, CAS rescuers must report within an hour to their base, where they're briefed before heading out with ropes and global positioning systems.

Calls to locate missing, overdue or injured hikers rose from 57 in 2005 to 66 last year. And in the first eight months of this year, the mountain search and rescue unit responded to 41 calls for help. Now with the approach of cooler weather, the teams are bracing for a peak season of emergencies. 'Sometimes we have to take a day off for a weekday emergency,' says Li, who joined the CAS eight years ago.

Fellow volunteer Li Yuet-sim enjoys working in the countryside with a group of like-minded people. 'It's teamwork,' she says. 'If we don't communicate well, we may put ourselves in danger during an operation. We're like a big family but from different backgrounds. Whether you're a CEO or someone from a grass-roots background, everyone is the same here because we share the same mission.'

A more loosely organised group, the Hong Kong Countryside Volunteer Search Team, also assists in weekend searches. Formed in May, it comprises about 200 hikers with varying trail experience, including a former CAS commander, mountaineering coaches and telecommunications professionals.

'If we know someone is missing, we want to help,' says Ling Kim-kwong, a retired senior police inspector and one of the group's co-ordinators. 'Each of us has our own expertise and our experience in the wilderness may help assist the government's search teams.'

Police call on the group when all official services, including the CAS, are already employed, and only with the permission of the families of those who are missing. The group says it has already had some success: it showed police in February how to detect a mobile phone signal, which helped narrow the search for 42-year-old book wholesaler Lo Si-fai, whose body was found near Ngong Ping, Lantau, after he'd been missing for a week. Last month, they found the body of Wong Chi-tim, a 76-year-old fung shui practitioner who hadn't been seen for a month.

'It's a great relief for us and the victim's family if we can find the body of a missing person,' Ling says. 'I've heard that a man is still searching for his brother who went missing on Lantau 10 years ago. To his family, it's a lifetime burden.'

Ling says he incorporates police tracking techniques into the group's search attempts. 'Hikers leave distinct marks when they walk through a wilderness,' says Ling, 55. 'We look out for the marks and disturbances created by their passage. Even though Wong was missing for a month, his marks were still there. The colour of the leaves and grass was different because they were damaged by his walking.

'We're honing our searching techniques and management,' Ling says. 'Next time, we hope to find not the dead body, but a living person.'

CAS volunteers - numbers now stand at about 115 - undergo more formal training. Recruits are taught first aid, map reading and abseiling techniques at CAS headquarters in Yau Ma Tei, and practise handling scenarios based on past rescues. After completing the training, they're put on standby duties at the Government Flying Service facilities at Chek Lap Kok airport, and must patrol the hills twice a month.

'Every step has to be done very carefully because it involves a life,' says Li Yuet-sim, a forecasting officer at the Hong Kong Observatory and a volunteer of nine years.

Too many ramblers are ill-prepared for their outings, says Johnny Chow Kwok-keung, chairman of the Hong Kong Hiking Association. 'I've seen many walkers who regard hiking as an impromptu activity,' he says.

'People who get lost or injured are often not in hiking gear. They dress as if they're going for a

stroll down a Mong Kok pavement rather than a rough path in the countryside.'

CAS volunteers relate similar stories. Li Fung-ki recalls the lack of preparation of a lone, young hiker rescued in a night operation from Kowloon Peak two years ago. 'All he brought along was an umbrella and a bottle of water. He didn't have any food, a whistle or torch.'

Hikers should never walk alone, Li says. 'The best is to go with at least four people. In an accident, one person should remain with the injured person,' she says. 'Others should carefully note the location and call the police.'

But even groups of hikers can stumble into trouble, says 15-year CAS veteran Lai Kong-fat, an electronics executive. Last year he helped rescue 17 members of a hiking club who were stranded near Yin Ngam Stream, in Tai Po.

A 70-year-old woman was in a bad way when they found her, Lai says. The Government Flying Service helicopter was called to evacuate her first, until the fading light caused a delay until dawn. Recalling how he kept club members company overnight at the site, Lai, 40, sighs.

'None of them wore proper hiking gear,' he says. 'Some wore sandals. Others only brought key ring torches.'

Rescues can take a toll on volunteers, too. Lai was knocked unconscious two years ago when his team's car crashed in a call-out to rescue a man on Ma On Shan.

'Sometimes we have to deal with life and death situations and put ourselves in danger,' he says. There's a satisfaction in saving a hiker's life, Lai says, but there are some incidents that rescuers will never forget.

'A woman fell from a cliff in Sai Kung while hiking with her husband, after she had trailed behind him on the path. An accident parted the couple forever,' Lai recalls. 'This is a lesson learned. Just a small mistake can end in tragedy.'

Useful sites for hikers

Mobile phone coverage - Office of the Telecommunications Authority (ofta.gov.hk/en/ca_bd/country_map/main.html)

Hiking guidelines and list of trails - hkwalkers.net/eng/index2_3.htm

Hiking groups - Hong Kong Hiking Association (hkha-china.org.hk); Hong Kong Trampers (hktrampers.com); Venture Society (venturesoc.org.hk); Hong Kong Adventurer (hkadventurer.com);