Inmarsat-5 Satellite Critical Design Review Successfully Completed Ahead of Contract Schedule

LONDON, October 12, 2011 -

Inmarsat plc (LSE:ISAT.L), the leading provider of global mobile satellite communications services announces that Inmarsat SA, one of its subsidiary companies, has successfully completed Critical Design Review for the Inmarsat-5 satellites, under contract with Boeing.

The Inmarsat-5 satellites are a key element of the new Global Xpress™ Ka-band network.

“This is a fundamental milestone and marks the transition of the project from a design and engineering phase to a manufacturing, integration and test phase,” said Franco Carnevale, Inmarsat vice-president, Space Segment.

During the review all aspects of the spacecraft design and operation were thoroughly reviewed by Inmarsat’s engineering and operation teams and by a Boeing independent review team.

“The review was completed earlier than scheduled, and the conclusion of the CDR board was that the design is mature and there are comfortable margins with all key performance parameters” said Carnevale.

Much progress has been made with the manufacturing of key elements of the first spacecraft including structure, propulsion systems and flight hardware such as TWTA. This means the Inmarsat-5 F1 is on schedule for completion and launch in 2013.

In parallel, plans for construction of the Proton launch vehicle which will lift Inmarsat-5 into orbit will be discussed at a programmatic kick off meeting with ILS and the vehicle manufacturers Khrunichev in early December.

Leo Mondale, Managing Director of Inmarsat Global Xpress, commented:

“Our new satellite fleet-build is proceeding at pace and with purpose. We are delighted at Boeing’s accelerated milestones and testing performance to date. With Global Xpress we will offer up to 50Mbps to a 60 cm antenna, at highly competitive price points. Inmarsat’s Global Xpress is unique in its global Ka-band spot beam coverage with state-of-the-art mobility management.  In addition, the service will be supported by multiple steerable beams on each satellite, which will enable us to direct significant capacity, in real time, to the exact location it is needed.

These beams have been specially designed by Boeing to serve, among other applications, the rapidly growing UAV demand for wideband channels, providing excellent value to governments without the need for capital investment.

The Global Xpress Program is fully funded and the successful satellite CDR represents real progress toward our entry into service in 2013″.

More details about Global Xpress can be found at www.inmarsatgx.com.

About Inmarsat

Inmarsat plc (LSE: ISAT) is the leading provider of global mobile satellite communications services.  Since 1979, Inmarsat has been providing reliable voice and high-speed data communications to governments, enterprises and other organizations, with a range of services that can be used on land, at sea or in the air.  The company’s services are delivered through a global network of more than 400 distribution partners and service providers operating in 100 countries.  For the year ended 31 December 2010, Inmarsat plc had total revenue of US$1,171.6 million (2009: US$1,038.1 million) with an EBITDA of US$696.1 million (2009: US$594.2 million).  For more information, please visit www.inmarsat.com.

Media Contacts: Chris McLaughlin, Vice President, External Affairs, Inmarsat, Telephone: +44-20-7728-1015, Mobile: +44-7796-276-033, Email: chris_mclaughlin at inmarsat.com