Dr. John Mock
Email: [email protected]
The Himalaya Range stretches from Bhutan to Pakistan, and the only series of maps that covers the entire region is the US AMS Series U502 at 1:250,000. These maps, published 1959-1963, were declassified by the US government when they were replaced by a newer series that is still classified and unavailable to the public. The U502 series has been reprinted, and color reprints can be obtained in the USA from Chessler Books, PO Box 339, Kittredge CO 80457. Edward Stanford Ltd, at 12-14 Long Acre, Covent Garden, London WC2E 9LP also sells reprints, although generally in black & white only.
The old British Survey of India maps, at 1:63,360, which were published in 1930, are long out of print and no longer available. I believe the Govt of India maps at a similar scale are classified.
At a scale of 1:500,000 are the Tactical Pilotage Charts, published by the US DMA. They are available from the National Oceanic and Atmospheric Administration. They are based on satellite information, and are topographically accurate, but at times wildly inaccurate about built features such as roads and villages. The scale is too large for on the ground trekking, but they are excellent for planning.
Other map series cover certain specific parts of the Himalaya. I would suggest you consult the several trekking guidebooks published by Lonely Planet, which list available maps and where to obtain them.