Mode S information required

[bluskis]

In the Private Flying Forum there is an alert that response to the CAA proposals on the Mode S requirements has a deadline of 24 Jan 03.

The concern of the GA sector is one of lack of reasonably priced equipment to meet the reqirements.

Could ATC elaborate on the subject, giving perhaps some opinions on the potential ATC problems if GA is exempted or partially exempted from carrying Mode S equipment, and the severity of the current problems which Mode S is intended to alleviate.

[Over+Out]

If you fly well clear (horizontally) of all CAS it will make little or no difference to ATC if you carry Mode 'S' or not.
If you fly near to CAS, e.g. north of LHR below CAS again it will not really effect ATC. However, it will make a difference to aircraft carrying TCAS( collision avoidance system), they will be able to find out what your level is and this will stop many nuisance TA's (traffic advisory) that these aircraft receive.
Each Mode 'S' transponder has its own unique code which groud radar can interrogate to give ATC very accurate information.
When a TCAS equipped aircraft (they already have Mode 'S' transponders) interrogate another aircraft I think mode 'S' is used , but I am not sure.
In the future Enhanced Mode 'S' will be used to give ATC much information automatically that we have to ask for today, e.g. selected level, IAS, G/S selected heading all from FMS.
So in the future if you operate in or near to (even under) CAS mode 'S' transponders will become very, very important to Mode 'S' radar equipped ATC units.

[chrisN]

So if there are 15 gliders soaring near Ridgewell, 6 out of Wethersfield, and up to 10 GA aircraft skirting the Stansted CTA round its north east edge, would ASC monitor all their Mode S signals as well as what's inside the CTA?

Or would ATC switch off all the signals from the outside-CTA traffic, as another ATCO said, to reduce clutter to manageable proportions, so negating any ATC benefits? (But still leaving TCAS benefits, of course - subject to the answer to another question, below.)

Even if ATC do monitor those 20-30 gliders etc., would ATC play any part in them avoiding collisions with each other, or would the pilots themselves still be the only ones able to avoid collisions, by eyeball as at present?

As for TCAS and height readings, I thought TCAS could get height from a mode C transponder - is that wrong?

Whether or not, someone else wrote that TCAS scan about 30 degrees above and below the horizon, so even without height data from the "target" aircraft/glider it either doesn't register or it is a potential conflict - is that correct or not?

(We glider pilots and many others in GA are struggling to understand the issues.)

[BDiONU]

Why would ATC monitor 20-30 gliders, even if they had the capability? I would suggest that any gliders, or any GA, outside of regulated airspace would be filtered out due to clutter.

bluskis:
May I refer the right honourable poster to the post I made this morning in the thread entitled 'Mode A code shortages'.
In a nutshell, don't expect Mode 'S' in UK anytime soon 'cause ATC cannot use it.

[Who has control?]

Wouldn't it be nice if code 7000 also meant to a TCAS 'I'm outside CAS - ignore me!' .

That would require a change to the TCAS box - which the IFR traffic already has, rather than foisting an expensive box on the GA community, which we don't need.

[Minesapint]

Because it would probably mean -

" I am squawking 7000, completely lost at FL150 and can see a lot of civil traffic - for gods sake don't ignore me" !!!;)