I should check my links more often- IATA have submitted a new edition for
user requirments for ATS...a year ago(slack me!)
Good read on what facility the airline industry is willing to pay for.
In general, IATA views ADS-B IN based on the 1090 Extended Squitter (ES) data link as the most desirable next-generation form of surveillance, while acknowledging that equipage requirements are
still being defined.
my italics
ICAO has formalized standards for three broadcast mode data links for ADS-B: 1090 MHz Mode S Extended Squitter (1090 ES), VDL Mode 4, and Universal Access Transceiver (UAT).
Although there are three standards, there is general global consensus, including IATA, CANSO, EUROCONTROL, FAA, Airbus and Boeing, to use 1090 ES as the supporting data link for
international ADS-B applications, as it is available and mature, enabling early implementation.
The majority of stakeholders do not support VDL Mode 4 after consideration of the risks and investments associated to its implementation versus the added value.
UAT carriage is of no interest to commercial air carriers.