Use of ILS Window

[Jat Jet]

Most of the latest Radar System are provided with ILS Window, which provides Azimuth and Verticle picture of aircraft on final approach. My question is for fellow ATCOs, where are the provision of its use provided in any ICAO document?. What action a controller should take when aircrafts is observed to be deviation form the ideal profile? Any other information would be welcome. Thanks:confused:

[Spitoon]

Never seen such a display myself - and I wonder where the data for the vertical position is derived from. I don't think you'll find anything in ICAO docs at the level of detail that you seek but a couple of provisions, although they need interpretation for the situation in question, come to mind from PANS-ATM....

8.7.1 Functions
The information presented on a radar display may be used to perform the following functions in the provision of air traffic control service:
...
g) maintain radar monitoring of air traffic;
and
8.9.6.1.8 An aircraft making a radar approach should:
a) be directed to execute a missed approach in the following circumstances:
i) when the aircraft appears to be dangerously positioned on final approach;

[Jat Jet]

Thanks a lot for prompt reply. Data is derived from the one of the radar system.

[chevvron]

He seems to be talking about PAR.

[Gonzo]

Our ATMs have the facility to show a side-on view of the last few miles of the approach, giving the glideslope positioning, on our AFDAS (Approach Funnel Deviation Alerting System...I think...).

Currently out of service though.

[Jat Jet]

yes thats what I was talking abt

[055166k]

Respected Pprune colleague........what a horrible piece of kit [AFDAS].
If an aircraft on the ILS deviates below the glidepath and has an unfortunate accident it might be attributed to pilot error. If the Controller has AFDAS a clever lawyer might attribute blame wholly or in part to the ATCO who failed to monitor the approach. Does the "union" have a view on liability protection....and dare I mention that "mode S" might fall into the same category of controller liability?

[Spitoon]

055166k, why pick on AFDAS?

The same could be argued for any number of errors that could be detected with bits of technology. What about a runway incursion when you've got a level II A-SMGCS? Or an AIRPROX after an aircraft has deviated from a route when you've got a track-adherence tool of some sort? Or following an excursion outside CAS when you've got radar?

But perhaps this thread isn't the place to ramble on with questions about who is responsible for what......



For Gonzo - out of curiosity, how is the vertical position shown on AFDAS derived?

[055166k]

Respect to another regular Ppruner. Where I'm coming from on this and similar topics..........Controllers are gradually being phased into a different job description by the drip-drip introduction of equipment and tools which have questionable value when compared to the more traditionally accepted ATC function of providing a service.
Do I want to see in the cockpit?
Does the pilot mind if I drive his aeroplane from the ground?
I sometimes wonder how aeroplanes have managed to get from A to B over the last few decades without all the toys and gadgets. Basically I'm far too busy to monitor the contents of the ever-growing size of the label data blocks........simple is beautiful.......let the pilot fly the plane.
The trajectory prediction tools being introduced at London ACC Swanwick may lead to the occasional incident......however it is the Controller who will be held liable and not the tools on which the tactical decision was made. Lifetime skills and experience will atrophy, and for new controllers they will never be learned. Perhaps they wont be needed anyway!

[Gonzo]

I'd imagine that if the AFDAS alarm went off (localiser tracking is the only function operational at LL currently), and the ATCO did nothing, there might be something to answer.

Spitoon....to be honest, it would be an educated guess. I'll check the facts and let you know.

[Neptune262]

We have a GP and LOC window option on our radar - I believe it is derived from the ILS approach angle and threshold position as programmed into the radar software and then it uses the standard mode C readout from the aircraft to plot a track and give warnings if required (either above/below glide or left/right of loc depending on parameters set)

It does look a lot like a PAR but is not to be used as such - I don't know whether you could give an SRA on one - ours isn't licenced for such. I believe it is more for information purposes. i.e. Confirm to the pilot that he/she is localiser/glide path established if deviance is observed.

Can't help with regards supporting documentation.

Note:- Certain aircraft types carrying out visual approaches can set off the warnings!!

[Capt Zorro]

chaps and chapeses,

the radar system I use has this feature and is derived from the ssr info supplied on return reply from acft.

However, this should never be used as a guide for below profile, the books dont cover it. but the controllers map display will show the approach path the usually the relevant fixes on the approach. also most approach positions (and the controllers should be aware of) have plates showing the min altitude the acft should be at, at relevant fixes on the approach, so if I saw a target 600ft below FAF I would be giving it a promp low altitude alert, and that it was below glideslope.

hooroo

[ALATOWER]

…we have got such display at the Tower position. Usually not PAR but only SRE and a/c transponders are involved in ATC systems like that, so giving advice during incorrect ILS approach we consider our guidance according 8.9.7 Surveillance Radar Approach doc. 4444

[SuzieWong]

We have one on our radar screen too - but nobody ever tell us what its for!
Typical Hong Kong training standard.:ugh:

[Spitoon]

the radar system I use has this feature and is derived from the ssr info supplied on return reply from acft.And this is the reason I'm interested in where the data comes from.

It sounds like this system presents data in what might be a misleading form (particularly to an old hand like me) - I'm old enough to remember when a radar display showed a pretty much raw data blip. The trouble is that when data is displayed in the same way but derived from a different source we can sometimes make assumptions about the data - and, importantly, how accurate it is.

Given the inherrent inaccuracies in mode C and the small differences in level between an aircraft on the glidepath and low enough potentially to warrant ATC action, my feeling is that it would be inappropriate to rely on mode C.



055166k, I think we're thinking along the same lines.

[timelapse]

I think AFDAS uses mode C for vertical information and from what I've read, it stops tracking GP adherence at about 1nm from the threshold due to limited height resolution.

[chevvron]

TLS would actually give you the info you require up to touchdown as it plots the 3D position of an aircraft using multiple receivers of the transponder signal; by measuring the time differential between replies at up to 5 sites around the airfield it can accurately plot 'position in space' rather than simply rely on mode C info.

[Jat Jet]

Thank you for all the contribution on the subject. The ILS window is tool provided by Raytheon radar system, the data comes form the fictious radar glide slope and llz course and pictutre comes from Mode C and RADAR. It seems to be for flight path monitoring and I do agree with one of the respondent that its accurcy will be doubtful.And it should be treated like by both controller and Regulator. In absence of guideline it causes apprehension abt the role it may play in any incident. Again thanks all for providing valuable comments