• Sceye's HAPS flew more than 15,000km from New Mexico to Japan before providing mobile services through SoftBank's core network
  • SoftBank tested calls, messaging, video, emergency alerts and drone connectivity as it works towards commercial HAPS service from 2027

The fact

SoftBank and Sceye have completed a HAPS trial over Kochi Prefecture in Japan as SoftBank prepares for commercial service from 2027. Sceye's lighter-than-air platform left New Mexico on 9 August and travelled more than 15,000km across the Pacific, reaching Japanese airspace on 23 August after about 13 days.

The aircraft remained over a target area off Cape Muroto and was kept within a radius as small as five kilometres for an undisclosed period. A 4G LTE-equivalent base station on the HAPS connected to SoftBank's core network through a ground gateway. The companies tested voice calls, text messaging, video calls, streaming and emergency alerts, including calls to Japan's 118 maritime emergency number.

SoftBank also tested communications with a drone and installed a mobile core and web server on the HAPS for an edge-computing trial. The onboard processing test recorded an average round-trip response time of 68 milliseconds.

The assessment

SoftBank has already shown that ordinary smartphones can connect to an airborne base station. This trial went further by using a stratospheric platform that travelled from the US to Japan, stayed over the operating area and carried familiar mobile services through SoftBank's network.

That is much closer to the job HAPS would have to do during a real network outage. The aircraft has to reach the right place, hold its position, connect back into the mobile network and keep serving phones on the ground. SoftBank has now tested that chain in Japanese airspace, including emergency alerts and a maritime emergency call.

There are still important gaps before this becomes a commercial service. SoftBank has not said how long the platform remained on station, how many users it served or how performance changed as traffic increased. One successful flight also does not show how several HAPS would be operated or replaced during a prolonged emergency. For BTW readers, the 2027 timetable now depends less on proving that a phone can connect and more on whether SoftBank can run the service reliably for as long as it is needed.

What to watch

Watch for SoftBank to define its first commercial HAPS service, including coverage, service duration and the number of platforms required. Longer trials should show performance under heavier traffic and how coverage is maintained when an aircraft leaves station. Regulatory approvals and the first disaster-response or remote-area deployment will also be important.