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On a high altitude climb or hike, there is famous safety rule for acclimatization "you should never sleep at an altitude more than 500m above the last night" One of my hike require to me camp at 4000m from 3100m, I wonder if there is any way to make it safe or break the rule. or spending extra day at the camp1(3100) and altitude gain during the day would help?

For example this advice from the CDC goes into more detail:

Ascend gradually, if possible. Avoid going directly from low elevation to more than 9,000 ft (2,750 m) sleeping elevation in 1 day. Once above 9,000 ft (2,750 m), move sleeping elevation no higher than 1,600 ft (500 m) per day, and plan an extra day for acclimatization every 3,300 ft (1,000 m).

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    Where did you find that rule? When hiking, an altitude difference of 500m is basically nothing.
    – PMF
    May 6 at 10:43
  • It's quite popular among hikers and I found it is claimed by multiple sources and hiking agency too. One refence I can provide here wwwnc.cdc.gov/travel/yellowbook/2020/noninfectious-health-risks/…
    – Kharak
    May 6 at 10:47
  • Rule is you can go as high as you want, but when you need go for a sleep on the same day, you shouldn't sleep at an altitude more than 500m above the last sleep. so sleeping at every 500m altitude is recommended.
    – Kharak
    May 6 at 10:50
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    I've edited in the most relevant quote from the CDC link, because (i) it establishes the claim, and (ii) it gives more context.
    – Chris H
    May 6 at 12:56
  • I think there are approaches that would have you sleep 2 nights at 3100m before going to 4000m, and on the day in between those 2 3100m sleeps, ascend as much as possible. But I can't quickly find a decent source so won't answer. Also it might make a difference what you're acclimatised to - if you live at 2000m it will be different to living at sea level
    – Chris H
    May 6 at 12:58

1 Answer 1

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Is it possible? Yes.

Is it advisable? Maybe. If you have to ask, probably not. Some Austrian or Swiss mountain guides even advise against sleeping elevation increase of more than 300-500m per day, especially above 4000m. Here for example (german).

Now these guides tend to err on the side of caution as they are primarily intended for novices. I.e. 500m per day will be fine for basically everyone except for those with medical conditions, special medication (or those being reckless, not eating/drinking/sleeping enough etc.). That means that most of the population will probably be able to handle more than 500m per day.

Now, since you have to ask, you apparently don't know if you belong in that category or not. Maybe you can easily take 1000m a day, maybe you are in the 1% of people who get HACE at 4000m. With more experience you will be able to tell how much you can take.

I would advise against it if:

  • you have known medical conditions related to your lung function etc.
  • you take medication for blood pressure/lung function etc.
  • you have experienced AMS (acute mountain sickness) at the target altitude
  • you are "unfit" or the hike itself will put you to your limits.
  • you are a heavy smoker

(incomplete list, just a few I can think of)

If you decide to do it, here are some precautions you can take:

  • DO NOT GO ALONE!
  • Always have an escape route, i.e. be able to descend at least 1000m quickly and do so if you experience AMS symptoms
  • Drink enough (3-4l a day)
  • Sleep an extra night at the same altitude before going higher (as recommended by the link above)
  • Get enough sleep and eat sufficiently
  • Ascend another 200-400m before going back down to you sleeping altitude
  • Try to reduce the weight of your pack (20kg seems a lot)
  • No alcohol
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    Observation: I have been on one big mountain 40 years ago--we ascended nearly 1000m/day--and 10 out of 12 of us were forced off the mountain with AMS. The two of us were unaffected, though, while we certainly felt the 4,700m elevation we had no AMS symptoms at all. It varies from person to person. May 12 at 3:19

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