|Quoting Max777geek (Reply 5):|
Tcas offers traffic patterns, what's ads supposed to give more ?
Let me try to describe more generally what kind of information is offered on these displays. Both TCAS and ADS
-B offer, to the pilots of other aircraft in the vicinity, the approximate location of and distance to traffic that might pose a hazard. TCAS is better than nothing, but has significant drawbacks. ADS
-B provides much more accurate position information about nearby traffic, provided that traffic is using ADS
Flight plans have nothing to do with traffic avoidance. A flight plan is a suggestion, and the actual route flown may have little or nothing to do with the flight plan, save the origin airport. In Class A airspace, that is above 18,000ft MSL in the USA, all traffic is in contact with ATC and being provided separation services, so it becomes less of a concern. The primary collision hazards occur when climbing or descending (due to reduced visibility) and around airports and common navigation points like VORs (due to the increased density of traffic). There may be a mix of IFR and VFR traffic, some which will not be in contact with ATC, and many which may not have filed a flight plan at all.
Every pilot is responsible to see and avoid other aircraft, whether flying IFR or VFR. TCAS, ADS
-B, and radar advisories from ATC are all just useful tools to assist pilots in avoiding each other. Again, the big improvement with ADS
-B will be more accurate position information about other aircraft, but it's not even close to being used widely at this time.
There is a feature in ADS
-B whereby some aircraft will be able to provide both a present position and a position vector, that is, the direction in which they are flying. But for me, the truth is that when I get within a certain distance of another aircraft, it doesn't matter which direction it was going at a certain time. I should maneuver to avoid the other aircraft irrespective of which direction it might go.