"The A340 reduced its speed on its own, miles too early on approach, to increase the distance from the preceding aircraft (based on the TCAS traffic display). It messed up the sequence and an A320 was then only 4 NM behind it! I was obliged to make the A320 perform an "S" for delay".
Be very careful that you do not use TCAS displays for functions that were not intended.
The incident above is from excellent article from Eurocontrol on
Incorrect Use of the TCAS Traffic Display. The article describes some of the limitations of the display.
One big issue is that the TCAS display shows relative positions. Your aircraft is a moving object, not a fixed point, and your interpretation of the relative motion of a target might be quite misleading.
Even if you are 'in trail' behind an aircraft 5 miles ahead, be alert to the fact that the TCAS traffic might not be the aircraft that you are 'number 2' to. Not all the targets in the display range are displayed.
Finally, it is not unusual for TCAS target bearings to be in error more than 5 degrees, possibly greater than 30 degrees
I have seen examples of this when my Wx radar paints nearby aircraft -- the Wx return and the TCAS target frequently do not match! In fact, I am more confident in the bearing accuracy of a Wx radar paint from a crossing/preceding/passing, than the TCAS bearing.
Having said that, I
do peek at the TCAS to see if I am closing in on a preceding. I just try to remain aware that "it" might not be "him."
Climbing to alt and falling into line behind other traffic, would the other traffic be displayed on the ND?
Not all targets are displayed, including targets that are proximate. There is a lot of fancy mathematics going on in that TCAS computer, and lots of IF and AND and OR stuff to boot!
Excuse me for asking, but what levels do you fly at? Would you be placed only 5 or 6nm behind a preceding at FL330, for example?