AALTO advances Zephyr towards commercial operations from the ‘Stratospace’
AALTO is intensifying flight testing of its solar-powered Zephyr aircraft as the Airbus subsidiary works towards certification and the global commercialisation of services delivered from the stratosphere.
Speaking to Aerospace Global News at the Farnborough International Airshow, AALTO CEO Hughes Boulnois described the layer between conventional airspace and satellites as the “Stratospace”, an emerging operational domain with potential applications spanning communications, Earth observation and defence.
“The Stratospace is the layer between space and conventional airspace,” Boulnois explained. “Because we are operationalising it and delivering services from the Stratospace, we have decided that it is a new domain of application and therefore it has to have its own name.”
What is AALTO’s Zephyr?
Created by Airbus in 2023 to commercialise Zephyr, Farnborough-based AALTO now employs approximately 220 people.
Its Zephyr High Altitude Platform Station (HAPS) is a solar-powered, uncrewed fixed-wing aircraft designed to remain above conventional air traffic and most weather systems for extended periods.
With a wingspan of approximately 25 metres but weighing only around 75kg, the aircraft can carry payloads weighing up to 8kg. AALTO is ultimately targeting missions lasting as long as 150 days.
Boulnois said this endurance would allow Zephyr to combine “the persistence of a satellite with the flexibility of a drone”.
Potential missions include environmental monitoring, intelligence and surveillance, and direct-to-device mobile connectivity. The latter could restore communications following natural disasters or extend coverage across remote and geographically dispersed regions.
“The importance of the Stratospace is that we can deliver observation missions to support the monitoring of global change,” Boulnois said. “We can also deliver telecommunication services directly to a device. You don’t need an antenna; you just need your mobile phone.”
Zephyr builds upon record-breaking flight
Zephyr completed a record-breaking flight lasting 67 days, six hours and 52 minutes in 2025, exceeding its previous 64-day endurance record.
Launched from AALTO’s operating site in Kenya, the aircraft travelled into Australian airspace, crossed the Intertropical Convergence Zone twice and passed through seven flight information regions. The campaign demonstrated both the aircraft’s endurance and the international regulatory coordination required to operate a HAPS across multiple jurisdictions.
“For us, 30 hours is only just the beginning,” Boulnois told AGN, contrasting Zephyr with the endurance available from conventional aircraft and other uncrewed platforms.
Spain flight campaign supports commercial readiness
AALTO is now undertaking a flight-test campaign in Spain as it works to demonstrate the readiness of the complete Zephyr system.
Boulnois identified three priorities for 2026: flying more frequently, expanding the company’s operational footprint in Kenya and continuing the aircraft’s certification journey with the UK Civil Aviation Authority.
Kenya is home to the first AALTOPORT, a dedicated facility supporting the launch, recovery and operation of Zephyr aircraft. The company intends to expand the site as it prepares to deliver commercial missions.
AALTO is also working with the Kenyan authorities to develop a regulatory framework for high-altitude operations.
UK certification could enable global Zephyr services
AALTO received Design Organisation Approval from the UK CAA in 2024 and is progressing towards type certification for Zephyr.
Certification would represent an important step towards commercial operations and could establish a regulatory model for other persistent high-altitude aircraft.
“We will continue our journey with the UK CAA on the certification pathway, which will be the enabler for global commercialisation,” Boulnois said.
“It will also be a first for the UK because they will be certifying such a platform for the first time.”
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