Luoto :
it is technically rather easy to downlink RAs, as the RAs are already broadcasted on the Mode S to co-ordinate with the other TCAS(s). To receive this you only need a fixed antenna relatively cheap.
But this pose serious ( legal ) problems. Because what the controller will see on his scope is an RA being issued by a system, not the fact that the pilot is following the RA. There are also short false RAs that are being transmitted but not resulting in an audio resolution in the cockpit, and also not all aircraft are TCAS equiped.
Downlinking RAs will solve some problems but create new ones as well. anyway it is being seriously studied by Eurocontrol and already tested in Japan.
Gunship :
there were not really 2 sets of rules on TCAS adherence before July 2002. Just the fact that an RA stands for Resolution ADVISORY and it was always up to the pilot in command to follow it or not.
( Visual aquisition of the intruder was even mentionned as a possible reason not to follow an RA ) Also some other aviation rules said that a pilot should always follow an ATC clearance unless in emergency, and an RA was not described as an emercency.
In this confusion some airlines and /or some State authorities delivered different instructions to their pilots.
But it is all relatively straightened now.
Reference the Guardian article.
A good illustration of what a wrong sentence can do in some minds :.
_____________________________________________________
quote :
He had wrongly instructed the Bashkirian airlines plane to descend, even though its onboard warning equipment told it to climb. The pilot followed the controller's instructions and ploughed into a DHL cargo plane that was descending in accordance with its own collision-avoiding equipment.
__________________________________________________
Everything is correct except the word " wrongly ". P.N. issued the clearance BEFORE anyone had announced an RA, as the RAs came AFTER the clerance... A world of a difference for us , ( as PN was issuing a correct clearance at that time ) but not to the general public who beleive what is in the news and condemmend him.
I again deplore that the names are mentionned. What does this bring ? More problems for the relatives staying behind , that`s all...
I start to dislike journalists .