Mathematical Problems in Engineering

Research Article

Extended Traffic Alert Information to Improve TCAS Performance by means of Causal Models

Table 3

Reachable scenarios with negative domino effect.


Domino effect	Case	Graphical illustrations	Descriptions

Conflict	1		() For threat 1, a TA is issued at 7:24:26. Aircraft 1 and Aircraft 2 would, respectively, take upward and downward manoeuvres at RA. () For threat 2, a TA is issued at 7:24:28, and only Aircraft 3 climbs to respond RA while Aircraft 4 keeps its heading. () Originally, Aircraft 2 and Aircraft 3 do not have a threat, but a TA is issued at 7:24:48 when both of them amend their headings. The time to CPA is 12 s that is enough to resolve the negative domino conflict.
	2	(0, −1, 1, −1): Aircraft 1 keeps its heading while Aircraft 2 descends to resolve threat 1; Aircraft 3 and Aircraft 4, respectively, take upward and downward manoeuvres to resolve threat 2. A domino threat would be initiated between Aircraft 2 and Aircraft 3, and the left time is enough to resolve it.
	3	(−1, 0, −1, 1): Aircraft 1 descends while Aircraft 2 keeps its heading to resolve threat 1; Aircraft 3 and Aircraft 4, respectively, take downward and upward manoeuvres to resolve threat 2. A domino threat would be initiated between Aircraft 1 and Aircraft 4, and the left time is enough to resolve it.
	4	(−1, 1, 0, 1): Aircraft 1 descends while Aircraft 2 climbs to resolve threat 1; Aircraft 3 keeps its heading while Aircraft 4 takes upward manoeuver to resolve threat 2. A domino threat would be initiated between Aircraft 1 and Aircraft 4, and the left time is enough to resolve it.

Collision	5		() For threat 1, a TA is issued to fire a warning at 7:24:26. Aircraft 1 and Aircraft 2 would, respectively, take upward and downward manoeuvres at RA. () For threat 2, a TA is issued at 7:24:28, and only Aircraft 3 climbs to respond RA while Aircraft 4 keeps its heading. () Originally, Aircraft 1 and Aircraft 4 do not have a threat, but a TA is issued at 7:24:48 and the left time is not enough to resolve the new encounter. At 7:24:51, Aircraft 1 and Aircraft 4 collide.