AALTO has claimed a new stratospheric flight record with its Zephyr High Altitude Platform Station (HAPS), with one of its vehicles having remained airborne for more than two months.
Launched from its AALTOport operating site in Kenya on 20 February, the record-breaking sortie totalled “67 days, 6 hours and 52 minutes of continuous flight in the stratosphere”, the company says.
After an initial activity to test a connectivity payload over Kenya, the lightweight aircraft was flown to Australia. “During this transit, Zephyr navigated seven different flight information regions… [and] crossed the Intertropical Convergence Zone (ITCZ) twice,” Airbus-owned AALTO says.
Control was maintained from the company’s stratospheric operations centre in Farnborough, Hampshire, the UK, and a ground control station in the USA, through three shifts daily.
Having surpassed a Zephyr vehicle’s previous endurance record of 64 days, the latest flight came to a premature end on 28 April, when an undisclosed problem forced the operator to ditch the aircraft in the Indian Ocean.
The company describes the controlled descent as having occurred in a pre-planned “designated aviation sanctuary area”.
“That demonstrates the safety of the aircraft – even if such an event happens we have the procedures and the technology to have a safe termination,” AALTO chief executive Hughes Boulnois tells FlightGlobal. The company will not provide further details while investigation work continues by relevant authorities, he adds.
Despite the Zephyr’s loss, Boulnois says the sortie was highly successful in meeting AALTO’s objectives. “We wanted to demonstrate our capacity to fly very far away, to cross the ITCZ, where there can be a high level of turbulence, and to continue to test our flight-control system.
“We pushed the aircraft in terms of boundaries – temperature, vibration,” he notes. “It is a very important step for us, in terms of being ready for the [programme’s] commercialisation next year.”
The solar-powered and electric-engined Zephyr conducted much of the flight at an altitude of 75,000ft.
AALTO chief technology officer Pierre-Antoine Aubourg says the aircraft had “a lot” of remaining flight-time available at the end of its flight. “It was our first time operating with a 12-hour night,” he notes, with previous flights having been conducted closer to the equator. “We were really pleased with the vehicle and the degradation of the batteries, which was a bit less than expected,” he adds.
“We will take off very soon again and go to Japan, to deliver demonstrations to our key shareholders and partners [HAPS Japan],” Boulnois says. Commercial services with the Zephyr will start in the country next year via a programme with mobile services company NTT Docomo and Space Compass.
AALTO intends to conduct multiple additional flights from Kenya through the remainder of 2025. “Part of the plan this year is to get a couple of aircraft in the stratosphere at the same time,” Aubourg notes.
Meanwhile, Boulnois says the company is seeing increased interest from potential military and commercial customers.
Among potential defence users in Europe, the USA and elsewhere, he notes: “Some want to go [ahead] very fast, and may want to fly during the summer. We are I think in a position to be able to support them.
“There are many countries now that are looking at HAPS in general but us in particular, because they are relying on technology that is not European- or sovereign-[controlled], like Starlink,” he says. “This is favourable for us.”
Telecommunications operators, including in the Asia-Pacific region, are looking for ways to expand direct-to-device network coverage.
“When people look at HAPS they look at the aircraft and the technology of the aircraft and tend to forget the end-to-end system that you need to manage it – this is what AALTO is currently demonstrating,” Boulnois says. “It is much more than an aircraft.”
