LARS/Transponders

[pipertommy]

Hi,i was just wondering is there a requirement for the use of a Mode c transponder whilst under a LARS service or can you request this service with only Mode A?Thanks in advance!:)

[Spitoon]

Don't think there's a requirement for a transponder at all - the AIP will have all of the definitive rules.

You can request a LARS without tx'der but the controller's job is made much easier if you have mode A so if he or she is already busy, a non-squawking aircraft may not be easily accommodated. Or, more simply, you'll find it far easier to get a service if you've got a tx'der. Mode C makes little difference to LARS.

[anotherthing]

There is absolutely no legal requirement for a transponder when asking for a LARS service.

It does make the controllers job easier though.

However; Mode C does make a big difference to LARS, if the rules are used to their full extent.

[flower]

Pipertommy,

As has already been said you can have a LARS with or without a transponder. Mode C should be used in conjunction with Mode A if you have it, haven't time to find the reference now but there is a bit in the AIP about it. Unless someone else in the meantime posts it will try to look it up for you later on.

http://www.ais.org.uk/aes/pubs/aip/pdf/enr/2010602.PDF

Here is the link for you, bit about selecting Mode C is on that page

( edited to add link)

[Flybywyre]

Your getting a LARS service !?!?! :D
Make the most of it with or without your transponder. Can you tell us where you are getting it ? I will fly there to remind myself of what it was like :8
Regards
FBW

[pipertommy]

Yes!No probs,out of Cardiff(during the week nice and quite),very helpful controllers!thanks all for the replys/advice,and thanks Flower for the link.
Bit off subject,but i`ve been away for a few weeks and heard someone talking of a ground frequency trial at Cardiff?Wondered if you could shed some light:confused:

[flower]

Pipertommy, I'm afraid I'm not a good person to ask as I have also not been at work as have a bit of a back injury ( lovely and bumpy that Peri track !!! )

We have a ground frequency available for special events, really don't know where on earth we would find the controlling staff to man a dedicated GMC position, but as I say I am so out of touch you probably know more than I do.

[pipertommy]

Thanks!May have picked it up wrong.The track has been closed,with all the rain we had its turned to mud between foxtrot and the echo-taxiway!!Saves having to call up on the r/t all the time when its in use.Been in Bristol doing the atpl groundschool what a great place some amazing stories!but back to reality for now anyway.:rolleyes:

[Red Four]

Well, as at least one LARS unit only has primary radar only, that must answer your question!

[pipertommy]

Thanks all! cleared that up:ok:

[bookworm]

Out of interest, does Mode S make any difference for ATSOCA for those of you at TC? A discrete Mode A code is still issued, so it doesn't reduce the (albeit minimal) head-down time at the pilot end.

[chevvron]

Bookworm: Since when have TC provided LARS/ATSOCA?

Flybywire: If you want to see LARS in action, you have only to go to White Waltham and take a trip with the Aero club there.

[bookworm]

Since when have TC provided LARS/ATSOCA?

Essex, Luton and Gatwick, despite not being part of the LARS network, usually provide a service if workload permits. Since when? At least the last 20 years, probably rather longer. ;)

And many of us flying in the area are most grateful for whatever can be provided on a best-effort basis. Because of the limited vertical band, the potential for collision is much higher than well away from the TMA. On Saturday afternoon for example, I was warned by Essex of a potential conflict close to BKY, coming straight out of the sun in the opposite direction. Without the traffic info -- thank you Sir -- it would have got uncomfortably close.

[throw a dyce]

Pipertommy
From a safety point of view it's much easier to find lost a/c with SSR.I have seen it numerous times,including one that got lost twice in the same area within 20 mins.
In our area we will ask you to squawk,identify and give a FIS.We have a lot of Military that tank around under the CTA,and SSR is invaluable.
If ModeC is used, it cuts down on the TCAS alerts,vectoring a/c over the top.
At Aberdeen we are not a LARS unit,but give a service subject to workload,which is often considerable.

[chevvron]

Oh I'm aware that a few controllers in TC Ops (rather than SVFR) will provide ATSOCA on a workload permitting basis, but there are a hell of a lot who won't do it under any circumstances. We've had traffic depart and transfer to TC 'clean' for joining clearance, and who are then without ANY type of service until they are cleared to enter depending on which controller is on duty - some will/some won't provide service prior to entry of CAS.
Obviously Aberdeen do try to provide ATSOCA too.
Getting back to the original question though; TC have the ability to select 'full' mode S labels, but it's highly unlikely that LARS units, being mostly airfield based, will have this luxury in the near future. Some AD authorities won't even pay for an SSR feed let alone hardware/software for mode S.

[chevvron]

Another point is the fact that modern primary radars, unlike their predecessors, cancel out unwanted clutter by using a 'threshold speed' in the processor. What this means is the controller may not be able to see non-squawkers with a ground speed of less then 50 or 60kts. In strong headwinds, this means that many light aircraft climbing or descending will only be seen on SSR until they level off and accelerate above the threshold speed.

[Il Duce]

You'll probably find that most LARS units will provide a service to "primary only" contacts subject to their workload. Having mode A is certainly a great help in maintaining track identity and alerting other ATC units of who is working what traffic. Mode C helps to create a 3D impression of what is going on out there and controllers can also tell if pilots are at the level they've stated they're at (provided the mode C is working within the required tolerance).
On that note, I was providing a LARS some time ago when a pilot came onto the frequency and asked if I could check his height read-out as he'd just had the transponder in for a service. After confirming his altimeter setting and the height he was indicating, I told him that his height read-out was within limits. Another pilot on the frequency obviously thought that this was a good idea and asked if I could check his height read-out too. "Certainly", I responded, "just switch on your mode C". Pause for a few seconds...... "I haven't got mode C." was his response. Nuff said!!

[davedek]

Even though the definition of LARS suggests only RAS or RIS, they still provide FIS is requested - and as it happens, they often will only be able to offer FIS if they are busy! So dont count on getting a radar service at all, you might find it doesnt matter what mode your transponder is on.

[GBALU53]

If you have certain equipment you should use it

If the aircraft the aircraft has a transponder it should be on see and be seen it can help others.

Pilots should know how immportent the transponder can be and know how it operates.

Some student pilots will try and navigate with instruments I.E. the VOR or NDB which they have not been tought to use, because it is in the aircraft they will fiddle around with and possible get a little lost, as they should have been using the map and looking out of the window??:ok: :ok:

Happy and safe flying squawk ident and we know where you are.:ok: :ok: