|Launch mass||2,068 kilograms (4,559 lb)|
|Start of mission|
|Launch date||4 June 1997|
Inmarsat-3 F4 is a communications satellite operated by the British satellite operator Inmarsat. It was launched into a geosynchronous orbit on 4 June 1997. It was located at 54° West longitude whilst in service, providing coverage of the Americas as AOR-W. It was replaced by Inmarsat-3 F5 at 54° West in Feb 2016, and the now retired Inmarsat-3 F4 was moved to parking at 144° West.  
In the United States, Inmarsat ground stations are licensed to operate at 1525-1559 MHz and 1626.5-1660.5 MHz via a mechanism called the ISAT List. The 1544-1545 MHz and 1645.5-1646.5 MHz bands are reserved for safety and distress communications.