jackbauer
Sorry Nigel but the first rule of TCAS procedure is NOT to maneuver based on TA alone. You must wait for the RA to trigger before you do anything
Who said anything about a TA and/or RA
TCAS is a vertical aviodance tool only, as discussed above. I know of no reason or rule not to use lateral avoidance
as well if I do not compromise the vertical avoidance.
If, and it's a big if, the event was as dramatic as described, then the TCAS "system" had either failed, either the equipment or one or more crews. You are a better man than I if you are going to fly into another aircraft you see and tell your maker "but TCAS said nothing"
As you say, "do not manoeuvre based on TA
alone". I would agree... However, a TA action (for us anyway) is to "attempt to see the reported traffic". What is the point of attempting to see the reported traffic if the subsequent drill is to fly into it
A TA
and/or visual sighting is not "TA alone".
So I am afraid my principles stick. TCAS is a vertical only mode, and judging / achieving vertical seperations is difficult - so let TCAS look after that. TCAS does not look after you laterally, and visually judging / achieving lateral separation is easier. If I felt genuinely threathened by traffic acquired visually, and TCAS appeared incorrect or silent, I would certainly take lateral avoiding action.
On your principle, with the Legacy v 737 midair, you are saying that if either crew saw each other, they should have just folded their arms and waited to die