 It can be fatal.If reaching the area by air from lower terrain, the traveller should acclimate to the high altitude by staying at least one night at the starting point (typically Manali), and plan to stay over at either Keylong, Jispa or Darcha before ascending to the highway's highest passes and plains after Darcha.Travellers should minimise the time spent at the high altitudes and therefore not stay over at Sarchu or Pang.