Passage was officially open again. Have a look at the satellite pictures here and here to see what it looks like. All in all, the Northwest Passage has most definitely been open and ice-free in recent years (and is now more regularly open and navigable); and there is no proof whatsoever that it was ice-free back in the 40s (or, indeed, in any other recent period) - but definitely wasn't open and ice-free when the 'St. Roch' made its difficult transits. Sources: ** The Conquest of the North West Passage : The Arctic Voyages of the St. Roch, 1940-44 -- Inspector Henry A. Larsen, R.C.M.P.                                                      The Geographical Journal, Vol CX Nos 1-3, July -- September 1947                            (The first page is accessible for free at : http://www.jstor.org/pss/1789190 )