More details about Canada’s proposed ADS-B network have been disclosed. As reported last week, Sensis of Syracuse, N.Y., won a Nav Canada contract covering up to 200 ADS-B stations for selective deployment across the country. Six dual installations are planned around Hudson Bay, currently non-radar airspace. The Sensis units support either ADS-B or multilateration, an alternative technique that accurately positions aircraft by triangulating their transponder responses. An eight-station multilateration network will cover Fort St. John, in northern British Columbia, and 11 stations will serve Vancouver’s Inner Harbor and its approaches. Both locations lose radar coverage at lower altitudes, due to intervening mountains and, at Vancouver, downtown high-rise buildings. Fort St. John is an oil drilling center, with increasing low-level fixed-wing and helicopter operations, while Vancouver has extensive private and commercial seaplane and helicopter operations that cross the approach and departure paths of its international airport.