Telecommunication and broadcasting systems using radio-relay/base stations on board the high altitude platforms are expected to create the largest business market among its possible applications. They could also be integrated with satellite- and terrestrial-based systems in the future to construct the more powerful mobile and/or broadband networks. Prototype onboard equipment and ground equipment are being developed on schedule in the fixed, mobile, and broadcasting services. The performance of them will be demonstrated and evaluated in the preliminary flight tests planned in 2002 using alternative aerial vehicles: a helicopter, a jet, and a solar-powered unmanned aerial vehicle (UAV), before flight tests using the high altitude airships. This paper presents activity in Japan on the R&D of wireless access systems using high altitude platform stations and the detail of the preliminary flight test program.