The present 2-meter AM air-band "Party line" originated as a military system in the biplane era. Today's military has many highly secure digital communication nets used for airborne operations from close air support to drone attacks.

The DOD likes the idea of using COTS products so wherever possible, they push military technology into the commercial domain to spread R&D costs and reduce the price they pay per unit. That's where the air-band replacement will come from.

Why would the FAA and ICAO want to do this? Bandwidth. Digital communication uses spectrum far more efficiently and it eliminates channel clutter so pilots hear just what they need to hear.

On Saturday, April 13, 2013 2:13:33 PM UTC-6, Bear wrote:
What is your proposal?





So, how is digital communication with 17,000 mph satellites possible with Doppler effects?



Nobody suggested GSM as an alternative to a global aviation-specific digital communications protocol.