@jox
Most of what you say is entirely correct. A suitably processed data stream of requisite speed can be sent from an aircraft via satellite to a ground station. The technology has been around for many years.
But this is not the problem.
As has been stated before, the difficulty arises when several hundred aircraft are sending their individual data streams to a satellite receiver, and for this data to then be retrieved, combined and sent down to earth station/s.
For a system to work in practice requires satellite base-stations which can control and synchronise the individual aircraft stations in every aircraft. Due to the relative high speeds and varying distances of the aircraft, this synchronisation is a difficult problem and the technical challenges of a comprehensive system are outwith what is currently installed.
With current technology it would be possible given funding to design such a system, and a number of companies are known to be interested. Of course Inmarsat is well placed due to its considerable experience in this area. However to cover all long-distance commercial aircraft would need new satellite capacity, new ground infrastructure (not just to receive the signal but somehow to store and forward it to the many diverse users), and new equipment in every participating aircraft. This implies huge expenditure at a time when airlines are going out of business for lack of capital.
Additionally any universal system would need agreement on design and implementation by all interested national and international bodies - not an easy matter as has been previously demonstrated.
Incidentally, without wishing to be rude but if you are dealing with the companies you should note their correct names:
"irridium" is Iridium, and
"immarsat" is Inmarsat.
Edit:
Would someone from Inmarsat like to comment?
Their contribution to this discussion would be very valuable.
Last edited by Sallyann1234; 22nd Feb 2010 at 11:15.