Mode S Enhanced Surveillance

[Shore Guy]

Just read a incident report where ATC (London) could read altitude set in mode selector.....

Does only Europe ATC have the capability to see the "new" paramameters (heading, IAS, vertical intent, etc.) of enhanced mode S?

[zkdli]

I think that there has been a thread on this before!
London Terminal control Centre, I think, is the only ATCC that is able to downlink the following parameters:
Selected FLight Level from the autopilot
The current IAS from the ASI
The current ground speed from the FMS
The current heading
The current rate of climb or descent.
LTCC use the Mode "S" in other ways as well to enable controllers to see in to the stacks when there is to much label overlap and garbling. They do this through the use of vertical satack lists, which give a vertical cut through the stacks.:)

[westinghouse]

hi all,


i was told that atc can even monitor the slections made on the FCU.
hence the impossibility of cheating.
the system does work as one pilot told me. atc had made him aware of a wrong altitude selction on the FCU ( airbus)

bye.

[120.4]

Yep, that's about right. London Area Centre get it shortly I believe.

It IS the single biggest enhancement of ATC safety since Secondary radar itself. Shortly before we got Mode-S there was a real nasty at BNN involving about 4 aircraft during the early morning charge; bomburst avoiding action by all aircraft. Mode-S would almost certainly have prevented that happening.

There have been plenty of probable incidents stopped by it. During the simulator trials, controllers were picking up about 60% (I think)of deliberately mis-Selected Flight Levels on departure and something just less than that for arrivals. (I'm sure somebody will have the correct figures - they were high). It gives you a headstart.

.4

[bookworm]

Shortly before we got Mode-S there was a real nasty at BNN involving about 4 aircraft during the early morning charge; bomburst avoiding action by all aircraft. Mode-S would almost certainly have prevented that happening.

Was the cause of that the tracking itself or the depiction? The vertical stack list is undoubtedly a great leap forward, but could it not (without selected flight level) have been implemented using Mode A/C?

I love the blurb BTW:

The most innovative function in the Mode S Tool Set is the VSL. It has been designed to compliment and support existing operations by providing controllers with enhanced vertical situational awareness in busy stack airspace

"BAW 19S is out of 140 for 130, EIN152 is out of 120 for 110 and by the way did I tell you what a wonderful job you're doing this morning, Bill?" ;)

[anotherthing]

Bookworm

The Mode S is downlinked which allows the vertical stack list to display to it alongside the Mode C.

You would not have been able to have a VSL without Mode S or at least not one that worked the same way...

The tracking would have worked i.e. using the intention code (LL,KK,SS,GW) and tying that in with a capture area for each stack, which is what happens now, but there would have been no way of spotting early if an A/C was likely to descend to the wrong level (i.e. level bust) as wee have now with the SFL.
Similarly unless someone was physically inputting levels into the system as they were issued, there would not have been a detection of allocation of same levels in the stack...
As for a warning if an a/c was about to bust it's level i.e. using Mode C if it went outside it's toelrance parameters (200 feet), this would happen at the same time as the STCA would go off (and still does - VSL is a complementary system - nice tie Bill) and would therefore afford no quicker warning to the controller... so the BNN incident would still have happened using a Mode C driven VSL.

A Mode C VSL would have been helpful wrt garbling A/C in the stack, but I do not know how accurate it would have been on it's own because of the possibility of inaccurate readouts (I'm sure someone who has a hell of a lot more knowledge i.e. an engineer would be able to tell us)

What the VSL gives us now is a clean indication of level vacation and an aid to detect wrong SFL's and therefore prevent a level bust from developing

[threemiles]

Maastricht uses Mode-S parameters, too.

[120.4]

Bookworm

The BNN incident was caused by ATC misidentifying that FL130 was available for use. The traffic at FL130 could not be seen because it was garbling with about 6 others either in or entering the stack. A Mode-S based Vertical Stack List (VSL) would have shown the ATCO immediately what was and was not available. Also when a mistake is made it flags up a warning.

The very first time that FL130 could be seen on an aircraft lable was as the incident was starting. In an attempt to quickly solve the developing situation a further error in level i/d was made (again, can't blame the bloke, traffic was garbling) resulting in traffic being dropped through traffic underneath.

When I watched the recording for the first time I felt that gut wrenching urge to be sick. At one point a tuppenny piece covered all 4 aircraft with no vertical separation between the two pairs. Correctly used Mode-S would have stopped this incident happening.

.4

[bookworm]

anotherthing, 102.4 thanks for the info.

A Mode C VSL would have been helpful wrt garbling A/C in the stack, but I do not know how accurate it would have been on it's own because of the possibility of inaccurate readouts.

Yes, that's what I was trying to get at. I imagine the VSL would have been much less reliable and less functional before EHS.

[45 before POL]

Not having mode s at my disposal at present, could anyone tell me if it will display a heading assigned by a controller?:confused:

[anotherthing]

45 before POL

It will not display it all the time (if the setup throughout NATS is the same as at TC), but if you hook the A/C you can see the heading the A/C is flying, you can even see it tick round when the A/C is in the turn

[zkdli]

Swanlake
You can also show the headings of all aircraft at once without hooking the label. Likewise you can do this for IAS and Ground speed.:)