SoftBank has unveiled plans to fly a high-altitude platform station (HAPS) aircraft to deliver direct-to-device network coverage over Japan, marking a significant step in the operator's strategy to complement terrestrial mobile infrastructure with non-terrestrial systems. The trial, scheduled for this summer, builds on SoftBank's major investment last year in US-based Sceye, a company specializing in lighter-than-air (LTA) HAPS vehicles, similar to zeppelins or blimps.
In the demonstration, a Sceye aircraft will launch from its hangar in Roswell, New Mexico, and travel across the Pacific Ocean to Japan under satellite-based control. Upon reaching Japanese airspace, the aircraft will establish a link with a ground gateway in Kochi Prefecture on Shikoku Island, located on Japan's Pacific coast. The primary objective is to deploy smartphone connectivity to simulate potential communication solutions in the event of a major disaster, such as the earthquake that struck Japan's Kumamoto prefecture last week.
Sceye recently completed a 12-day, 6,400-mile stratospheric flight using its SE2 HAPS model, traversing from New Mexico to the coast of Brazil—a record flight time. SoftBank intends to test whether the aircraft can replicate this performance under Japan's unique weather and environmental conditions. The trial will also assess whether telecom services can be delivered from an altitude of approximately 12.4 miles at a quality comparable to terrestrial mobile service, and whether HAPS radio transmissions cause harmful interference to surrounding ground-based mobile networks.
SoftBank confirmed that the preceding aircraft, network, and gateway preparations are now complete. The operator also completed an end-to-end communications test linking the equipment intended for the HAPS aircraft to its Japanese mobile core, successfully testing voice calls, SMS, and mobile data across the full Japan–United States path. This verified that a standard handset could communicate through the planned HAPS access equipment and onward into the operator's existing core-network environment.
HAPS is a key element of SoftBank's broader Ubiquitous Transformation (UTX) strategy, which aims to bolster terrestrial mobile networks with non-terrestrial infrastructure during disasters. Rival telecom NTT DoCoMo has pursued similar ventures, recently claiming to have carried more than 5 million connections to its consumer-facing Starlink service. In its announcement, SoftBank emphasized the distinctions between HAPS-based connectivity and its own Starlink offering, SoftBank Starlink Direct. While Starlink Direct is intended primarily for mountains, islands, marine areas, and other locations outside ordinary network coverage—offering broad, basic reach—the HAPS service is designed for suburban areas, aerial applications, and other uncovered locations requiring service closer to the quality and capacity of a terrestrial network, with a maximum coverage diameter of about 200 kilometers. This provides a more localized, higher-capacity layer capable of supporting ordinary voice, messaging, and data services.
SoftBank added that commercial HAPS operations are targeted for 2027 or later. "Our vision is to expand today's 2D communications infrastructure into a 3D communication network extending into space. To achieve this, we'll connect multiple HAPS platforms with low Earth orbit (LEO) satellites using optical wireless communications, creating a multi-layered, 3D telecommunications network," said Masayuki Kamimura, senior director at SoftBank's Ubiquitous Network Planning Division. "Ultimately, we believe this network will support future innovations such as advanced mobility and AI-enabled services, while contributing to a broader digital transformation across society."