Serious trekking emergencies are rare, but illness, AMS, storms, missteps, landslides and even avalanches can happen to anyone. In non-urgent cases, your best bet is to be carried by porter (around Rs2500 a day) or pack animal (around three times that) to the nearest airstrip or health post, although bear in mind that medical facilities outside Kathmandu and a few other major cities are very rudimentary. Locals are the best source of information as to the nearest and quickest way to access health care.
Where the situation is more serious, phone (or send word to the nearest village with a phone, satellite phone or police radio transmitter) to request a helicopter rescue. Write down and repeat your message as clearly as possible, indicating the severity of the problem as well as your location – ideally at the side of a large field for landing. Note that it could be 24 hours between an accident and a helicopter reaching you, partly because many helicopters can only fly in the early morning. Helicopter rescue costs in the region of $2000 per hour, which means around $2000 in the Annapurna region, or upwards of $5000 if you’re high on the Everest trail. Helicopters won’t come until they’re satisfied you’ll be able to pay. This usually means finding a lodge owner willing to process your credit card, though it may also be possible if you have left a copy of your insurance documents with your embassy or trekking agency. Registering with your embassy will also speed the process of contacting relatives who can vouch for you.