The most common disappointment on a Himalayan helipad is a group being told the aircraft cannot take all of them. It is almost always avoidable, and avoiding it means understanding one piece of physics.
Thin air, less lift
A helicopter rotor generates lift by moving air. The thinner the air, the less lift for the same power. Air density falls with altitude and rises with temperature, so a helicopter at Gorakshep at five thousand metres on a warm afternoon is operating in dramatically less capable conditions than the same machine at Kathmandu on a cold morning.
The practical consequence is that useful load, the total of passengers, baggage and fuel the aircraft can lift, shrinks as you go up.
Rough figures
These are indicative only. Your crew calculates the real number on the morning using the actual aircraft, temperature and fuel state.
| Departure altitude | Typical useful load | Realistic passengers |
|---|---|---|
| Below 3,000 m | around 480 kg | 5 |
| 3,000 to 4,000 m | around 430 kg | 4 to 5 |
| 4,000 to 5,000 m | around 380 kg | 3 to 4 |
| Above 5,000 m | around 320 kg | 2 to 3 |
Why baggage is limited to fifteen kilos, or ten, or five
Because every kilo of baggage is a kilo that cannot be a person or fuel. The limit is not a fee-generating device. It is the number that comes out of the calculation for that route.
This is why the allowance falls as the pad gets higher. Fifteen kilos out of Lukla, twelve out of Pheriche, ten out of Gorakshep, five on a scenic flight that has to climb above five thousand metres and come back.
Balance
Weight is not the only consideration. Where the weight sits matters too. The crew will seat passengers to keep the centre of gravity inside limits, which is why you may not get the window seat you wanted, and why asking to swap after loading is not a small request.
Being honest about your weight
You will be weighed, with your bag, before a flight from Kathmandu. This is not an indignity, it is the input to a calculation that determines whether the aircraft can take off from a 2,845-metre strip. Estimates are no use. If you are travelling as a group and someone is considerably heavier than average, tell us at booking rather than at the apron.
Planning around it
Fly from lower where you can. Walking down from Gorakshep to Lobuche, or from Khare to Kothe, frequently turns two lifts into one and saves money.
Send gear ahead. Porters can carry what the aircraft cannot.
Take the first departure. Cold air is dense air. The 06:30 flight lifts more than the 11:00 one.
Use the calculator. The price calculator on this site runs a conservative version of this arithmetic and will warn you before you book.