Hi, peekay4 you are suprisingly off here, I am afraid. Comapred to your standards, that is . You cannot hit one aircraft into another without including the second one in the collision, right?
FD, just saw the fine print.
No, I am not off, as both toseg and ManaAdaSystem have confirmed exactly what I wrote through their actual experiences.
As mentioned previously, it's not unusual at all for
only one aircraft to receive an RA. In fact, it is the norm, due to the elongated shape of the protection area. TCAS II
facilitates RA coordination between aircraft, but does not
require both aircraft to receive RAs.
Here's a typical TCAS II protection area diagram (2D view):
Notice that the area is asymmetric front & back. Since the protection area is not a circle (sphere in 3D), one can easily construct a scenario where the intruder aircraft is within the other aircraft's RA zone, but not the other way around.
With TCAS II, the
first aircraft that generates an RA will transmit its maneuvering intention (e.g., climb, descend) to the other aircraft,
but this transmission in itself does not force an RA on the 2nd aircraft.
If (and only if) the 2nd aircraft also generates an RA some time later, the first aircraft's intention will be taken into account by the 2nd aircraft in issuing a coordinating RA, subject to whatever inhibits are active at that time.