An illustration of an I-6 F1 satellite launched in late 2021 to replenish Inmarsat MSS services now controlled by Viasat. Credit: Airbus

Update: Inmarsat said in a later April 18 statement that it had successfully transferred maritime safety services to a “contingency satellite” it did not disclose “immediately following the incident.” The company said it expects to bring its Inmarsat Classic Aero services online soon, and will then a focus on “the restoration of other services.”

COLORADO SPRINGS — An aging Inmarsat satellite that pilots use to keep in touch with air traffic control beyond the range of very high frequency (VHF) ground radars is experiencing a prolonged outage.

“There has been a technical issue with Inmarsat’s I-4 F1 satellite, which provides L-band services in the AsiaPacific region,” a spokesperson for the British operator said April 18 via email.

“Recovery procedures to restore services have begun and during this process Inmarsat will be providing updates to partners and customers impacted.”

The company did not provide other details about the incident, which started April 16, including how many partners and customers are affected.

Pilots are being advised to communicate with air traffic control using legacy high frequency (HF) radio technology over areas terrestrial VHF is unable to reach, mainly oceanic regions.

The maritime and agricultural industries also rely on I-4 F1’s L-band for communications services in the region.

Germany-based Inmarsat service provider m-cramer Satellitenservices described the issue as “a full service outage” that is affecting all the satellite’s L-band services.

“Due to the nature of the problem and the complexity of the recovery procedure, Inmarsat expect this to be an extended outage,” the German company said April 18.

An update is expected from Inmarsat at 1 p.m. Eastern April 18, m-cramer Satellitenservices added.

Built by EADS Astrium, now Airbus Defense and Space, I-4 F1 has been operating beyond an initial 13-year design life since its launch in 2005.

The satellite is due to be replaced by I-6 F1, which has a hybrid L- and Ka-band payload and launched toward geostationary orbit in December 2021.

Although I-6 F1’s Ka-band payload has since started service, the L-band payload is not expected to come online until the third quarter of this year.

Jason Rainbow writes about satellite telecom, space finance and commercial markets for SpaceNews. He has spent more than a decade covering the global space industry as a business journalist. Previously, he was Group Editor-in-Chief for Finance Information...