View Full Version : One Blip!
millerman
9th Jul 2003, 05:35
I had a strange situation the other morning,a B744 and 2000ft above a B777 both overflying my sector.Their ground speeds were exactly the same and there was only one position symbol showing on the radar!
I know this doesn't happen very often but i didn't like the look of it/wasn't very comfortable with it,so i split them up.The previous controller didn't and i was wondering how many of you out there would have split them?
Also any pilots reading,would you have been comfortable with the situation?
Onan the Clumsy
9th Jul 2003, 05:56
Maybe that's how they got the 727 out of Angola.
PPRuNe Radar
9th Jul 2003, 06:08
Not sure I understand it fully.
Did you mean that only one data block was showing (and one shielded) ?? Or just that they were directly on top of each other causing difficulty in reading the labels ??
2000' vertical separation is double that required so it wouldn't give me any heartache.
The only problems I have seen with closely spaced aircraft is corruption of Mode A and/or Mode C as the SSR receiver adds both responses together.
If it is a major concern to you, then ask one of the pilots to offset by one mile. Most modern FMS aircraft can do this in a couple of button pushes.
bekolblockage
9th Jul 2003, 06:47
No offence.....but you've been doing ATC for how long???
Lots of strange things can happen when SSR returns are close enough to garble.
Minesapint
9th Jul 2003, 17:14
This should not be allowed to happen. I hope you reported it?
Lucky a military crosser was not present taking 5000' on the mode C
millerman
9th Jul 2003, 21:03
They were exactly on top of each other so there were two symbols it's just that they were at exactly the same position!
i was wondering what would happen if the higher one had an emergency descent!
I did ask the pilots if they were happy with the situation but they didn't seem too bothered,but they weren't very talkative as they had just been flying for most of the night and were almost at their destination.;)
panjandrum
9th Jul 2003, 23:32
Well you could always switch the radar off and revert to Procedural control!? Would that help you rest easier?:D
If we had to switch the radar off, we might as well close shop entirely.
I was told that if one was to initiate an emergency descent, they usually start the descent with a turn in order to achieve max descent-rate without exceeding VNE. Or something like that...
Red Dragon
10th Jul 2003, 01:14
Golly!! How exciting. I bet it made the shift just fly by!!
:zzz:
FWA NATCA
10th Jul 2003, 01:18
millerman,
This happens more than you realize, so just offset the data tags and sit back and relax.
Mike R
NATCA FWA
Scott Voigt
10th Jul 2003, 10:42
Miller man;
Sounds like too much worry about nothing... As long as the data tag was still following along then they are up there <G>... We have that happen here ALL the time... No excitement at all. Just move the data blocks so that you can read them and go back to the stories at hand <G>...
regards
Scott
There was no problem, I was on duty also and saw this and wandered over to discuss if they could see each other on TCAS . The two were one blip with two labels for quite a while , around 10 mins , moving steadily westbound as one. It was interesting rather than worrying and we all just wanted to know what the crews thought .
EuroATC
10th Jul 2003, 16:29
So let me see if i understand, 2 targets co-located... so you see only 1 blip but still see both tags showing respective altitudes? Don't see the problem ladd, happens all the time where I have worked...if things like this worry you???