Inmarsat Announces $1.2bn Investment in Next Generation Ka-Band Satellite Network

Targeting a $1.4bn Incremental Market Opportunity

LONDON, August 6, 2010 - Inmarsat (LSE: ISAT), the leading provider of global mobile
satellite communications services, today announced that it has agreed a
contract with The Boeing Company ("Boeing") (NYSE: BA) for the delivery of
three state-of-the-art 702HP Ka-band satellites. The Inmarsat-5 constellation
will enable Inmarsat to provide a unique global high speed mobile broadband
service offering.

With operations expected to start in 2014, Inmarsat-5 will
support a next generation global service, Global Xpress, which will target a
$1.4bn incremental market opportunity in VSAT services. Global Xpress will
address the established, growing markets for VSAT services in the Maritime,
Energy and Government sectors, with further growth potential in developing
markets such as the Aeronautical sector. Global Xpress will deliver seamless
global coverage and unprecedented mobile broadband with speeds up to 50MB/s,
to customer terminals from 20-60cm in size.

Inmarsat will target $500m of annual Ka-band revenues 5 years
after global service launch. Under a separate arrangement, Boeing has agreed
to become a distribution partner for both Inmarsat's Ka- and L-band services
and has pre-committed to capacity purchases representing more than 10% of
Inmarsat's target Ka-band revenues in the first five years after global
service launch.

Inmarsat estimates that the total cost of Inmarsat-5 and
Global Xpress will be $1.2bn over 4.5 years, incorporating the fixed cost of
the satellites, as well as the cost of additional ground network
infrastructure, product development, launch services and insurance.

Andrew Sukawaty, Chairman and CEO of Inmarsat, said: "This is
a new investment for new growth. With the Global Xpress network, we will be
the first operator to offer global mobile broadband coverage, offering
unparalleled speeds and bandwidth to customers in remote locations around the
world. Global Xpress will be faster and less expensive than current Ku-band
market offerings, delivered to smaller and cheaper terminals and be the first
offered on a seamless, global, end to end basis with high quality of service.
Picture 50MB/s services to a ship or aircraft and 10MB/s to an antenna the
size of an iPad (20cm).

Inmarsat-5 will also complement our existing global L-band
services, allowing us to offer unique hybrid packages using both networks,
giving users unprecedented levels of resilience and reliability in remote and
harsh environments."

Rick Medlock, Inmarsat's Chief Financial Officer commented:
"We expect the Inmarsat-5 programme to be largely funded from our internally
generated cash flows and, with significant available liquidity today, we see
no immediate financing needs. In connection with the Boeing contract, we are
seeking Export Credit Agency financing support from the US Ex-Im Bank, which
could provide an attractive source of long-term debt. Given the multi-year
build phase and the strong free cash flow from our existing business, we
believe the peak impact on our ratio of net debt to EBITDA will be less than
0.5.

Furthermore, as a result of our investment in Inmarsat-5, we
will move to a more gradual replacement of our L-band network, resulting in a
deferment of more than $500m of our previously planned replacement
expenditure over the next 11 years."

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 2009,
Inmarsat plc had total revenue of US$1,038.1m (2008: US$996.7m) with an
EBITDA of US$594.2m (2008: US$531.2m). For more information, please visit
www.inmarsat.com.

About Boeing Defense, Space & Security

A unit of The Boeing Company, Boeing Defense, Space & Security
is one of the world's largest defense, space and security businesses
specializing in innovative and capabilities-driven customer solutions, and
the world's largest and most versatile manufacturer of military aircraft.
Headquartered in St. Louis, Boeing Defense, Space & Security is a $34bn
business with 68,000 employees worldwide.

For further information, please contact: Chris McLaughlin, Inmarsat plc, Telephone: +44(0)20-7728-1015, Mobile: +44(0)7796-276-033, Email: chris_mclaughlin at inmarsat.com;
Angie Yoshimura, Boeing Space & Intelligence Systems, Office: +1-310-364-6708, Mobile: +1-310-227-6568, Email: angie.e.yoshimura at boeing.com