a dodgy one

[avard]

here's a dodgy one,

flew past (5+ miles abeam) Sheffield on Saturday in IMC, though at the time we were between layers and visual, talking to Sheffield who knew we were IMC, they advised us of traffic 4 miles ahead passing left to right and descending, fortunately we were visual and had them in sight. A medium biggy with perhaps 50 on board. It passed by and turned and passed by again bit closer this time, going into Sheffield. It was some way off and not a problem, cos we could see them.

But, what if? Sheffield has no radar, uncontrolled airspace and us bumbling alone IMC along with the other one, don't know if they have lickle radar with us on it? are they equipped with them?

What would the passengers think if the Capt'n had bing bonged them with
"ahem, capt'n here, we are now descending into Blogs ville, those with St.Cristophers please rub them now cos we ain't on anyone's radar screen and we have just been informed of a didly donk flying towards us at similar height, recon we'll be ok cos we do this everyday and it hasn't happened before, er, no use looking out the windows cos they is white man"

makes you wonder dunt it

[CessnaEng]

They will have TCAS although I doubt they have 50 people on. I believe the only schedule at SZD now is Belfast using J41.

Of course initially SZD wanted its' own controlled airspace, sounds like you agree.

[Romeo Romeo]

When ever I've been past Sheffield they always give me a squawk, so I'd imagine they have at least some radar capability. My understanding was that biggies do get a radar service from someone whilst outside controlled airspace. I've come across them going into places like Teesside and ATC does go to great lengths to make sure they are separated from us lot.

[AMEX]

Romeo romeo you are probably right, the biggy must certainly get a radar service like you ask for but only as longt he radar service is not limited due to poor radar performance or limited radar coverage (happens everyday).
- I am not too familiar with the sheffield area so the following may not apply but wherever you are, Class G remains class G with its rules and responsabilities. ie the controller can't do much to help you.

Using a personal and daily experience, when I descend towards Filton, I usually get a sqawk 50 miles inbound with a RIS from Radar. Great you think but not that great because as it happens, I fly near Gloucester at a relatively low altitude and there is nothing that tells me how much traffic there is in the area at that time. Filton is only aware of people who talk to them, not the gloucester traffic manoeuvring at various height. Of course It is good idea to inform Gloucester of my presence (usually about 20 miles West) but it is if I have the time for it and again only 100% useful if they have been made aware of any activity.

My points are:
-Do not assume that ATC knows all about every traffic in the sky. They simply don't.
As a matter of fact my ex house mate is an ATCO which allowed me to realise how little there is they can do if we don't do our bits (and know the rules, limitations and pilot/ATCO responsabilities). Very scary how much I took for granted :eek:

-Class G is scary as hell and I try to avoid it as much as possible
but that is because I can.
-Flying IMC without radar service (RIS or RAS) seems rather risky (my own perspective)
-As for TCAS, not that CessnaEng said otherwise but just as a reminder, It only works with Transponder Mode C SELECTED.

Good night

[Chilli Monster]

Romeo RomeoWhen ever I've been past Sheffield they always give me a squawk, so I'd imagine they have at least some radar capability. No - Sheffield have no radar at all. The squawk is allocated so that other SSR equipped units can see that you are working them, so that they know who to ask should the need arise for traffic information or co-ordination (The same is the case for Cambridge).

Amex

We can actually see traffic even if it isn't talking to us. 20 West of Gloucester is inside our LARS coverage so the chances are that people there will be talking to us, but even if they're not providing they're squawking with mode 'C' the traffic information we can give you should do the trick. Otherwise you'll get the "Traffic Left / Right, x o'clock, range n miles, crossing you left - right no height information" better than nothing you have to agree. (40 miles north we can see primary only down to about 2000'). Pop in sometime if you want to see how much we can do for you (have you just started flying a certain based companies twins by any chance? :D).

And the reason for the 'Mode C' being in bold? A letter in a recent aviation magazine highlights the point that quite a few people in Mode 'C' equipped don't always select it. If you've got it then PLEASE select it. It makes life a lot easier for everyone.

CM

[englishal]

What I find disconcerting, is that often when joining VFR into a class D controlled airport, I have been told to switch the transponder off.....otherwise the controllers get too much clutter on their screens apparently....

Seems very un-natural to me...

Cheers
EA:)

[Field In Sight]

I was just about to post a topic similar to this thread anyway.

But as it's related, he's my question.

I obtained my IMC rating in the US and now want to regain my currency back in the UK so that I can fly further afield without struggling to get back home scooting under a low cloudbase.

I am comfortable flying in IMC but must admit that I am uncomfortable with the level of service that I could expect in uncontrolled airspace e.g. lack of LARS services at the weekends.

Does anybody fly in IMC using just a FIS. I would at least expect a RIS. It's nice to be told you are about to hit somebody before you do.

Thanks.

[Chilli Monster]

EA

Imagine a screen 20 inches in diameter, which equates to 50 miles radius. Now imagine a busy circuit within 3 miles of the centre - each one with a label showing code and level, or 'NMC' if no mode 'C' fitted.

It might seem un-natural to you, but do you get the idea now as to why it's necessary? There is no need to squawk in or joining the circuit. Class 'D' being a known traffic environment you are under the control of the tower controller being separated visually but using the reduced separation allowed in the circuit.

Now - take it one stage further. You're instructed to orbit at the end of the downwind leg, to allow an IFR inbound in that's at 3 miles on the ILS. You're still squawking, IFR gets a TCAS 'RA' and goes around unnecessarily. You're not going to endear yourself to him or ATC if that happens.

Field in Sight

Welcome to the world of personal risk assesment and planning. If you're going to fly IMC in the UK at weekends you have to bite the bullet and accept the following facts.

1) The IMC is best served to get you VMC on top.

2) When you do go IMC non-radar then limit the risk (correct quadrantal)

3) When you descend non-radar never bust MSA. If you're still IMC at that point then make the decision to divert to a suitably equipped airfield in plenty of time. You can either cloudbreak there to resume VFR or land there. A taxy or train is cheaper than a trashed aircraft!

4) Plan every flight expecting to divert - treat getting home as a bonus ;)

Don't become a statistic - happy landings

CM

[Wee Weasley Welshman]

Which is EXACTLY what happened at BRS recently. Short final in a 737 and suddenly a TCAS RA - "Climb, Climb Now". So its 44k of thrust time and an interesting ride for the pax as nearly a ton of Avtur gets converted into heat and forward motion... All because blogs in his PA28 had his transponder on whilst orbiting on base.

For gawds sake squawk mode C 7000 if you have it at all times. We have very good TCAS in many aircraft these days. I can often look down or up 7000ft from my level to see transponding aircraft out to 80+ miles ahead or behind...

WWW

[AMEX]

Chilli Monster :
:D :D :D The deal is, I bring the chocolates and you do the tea, alright ? That is of course if I manage to cross the 100 yards between my office (not the A/C) and yours (and by the look of it we are talking about the same place).
Send me an email at [email protected], it will be my pleasure to pop in and meet you all (I hear you are quite human ;) ).

As for the level of service provided and what can ATC do for you, I really meant to say that pilots shouldn't rely only on their beliefs (ATCO will sort me out anyway) because the responsabilties are shared and rarely only down to one entity (ATCO or Pilot).
Knowing the rules and understanding the environement we evolve in is essential (not that I always do mind you :rolleyes: ).

Speak to you tomorrow CM

[englishal]

Just curious, and not wishing to start an arguement...but why elsewhere can they control a large number of aircraft, heavys coming in on the ILS while a PA28 is landing on another runway...yet they insist you have operational Mode C. Likewise landing on a parallel runway at the same time as a 737 is coming in?.....Why isn't their TCAS kicking off all the time? Do they have different / more advanced kit ?

I understand that Clutter on the screen could be a problem, seems pretty obvious, but although you say its controlled visually, I have been told to 'take the next right and contact ground' when I'm still on a 1 mile final :)

Cheers
EA:)

[bluskis]

If ATC tells you to squawk a number, or go to standby or off, I presume it to be normal to comply.

WWW

Are you saying that by squawking C7000 in our little ones your TACS is not triggered , or that you are able to assess there is no risk?

[Chilli Monster]

EA

You won't start an argument. You're just showing you don't fully understand how TCAS works. You've also answered your own question - A DIFFERENT RUNWAY. We're talking about same runway Ops, where the orbitting aircraft can be seen as a threat when it's flying towards the approach track on that part of the orbit.I understand that Clutter on the screen could be a problem, seems pretty obvious, but although you say its controlled visually, I have been told to 'take the next right and contact ground' when I'm still on a 1 mile final And your point is? At one mile you're still being controlled visually - this might come as a shock but we can see you on that one mile final. The idea of a Tower controller after all is to LOOK OUT OF THE WINDOW ;), not use radar (illegal in the UK). I actually think this instruction is poor controlling technique - what if you miss the turn off? UK procedures and instructions all have to be 'fail-safe'.

Maybe it might be worth learning how both sides of the atlantic work, rather than trying to answer UK questions with US answers?

I recommend SSR Operating Procedures (http://www.ais.org.uk/uk_aip/pdf/enr/2010602.pdf) for anyone flying in the UK.

CM

[englishal]

"And your point is"

My point is that the tower controller thought I was someone else. He thought I was on the ground, when in fact I was on final....not very good for controlling visually (I know this because when I told him I was still on final he had to ask who was on the ground)

In my example of different runways, these are intersecting runways, 30 & 25L and from the aircraft on ILS 30 the PA28 on final for 25L might look like a 'threat'..... Several times I have 'raced' an aircraft on the ILS, to land a minute or so before them on 25L. If this doesn't trigger the TCAS then I can't see why an orbiting aircraft would trigger it....But you're right I don't know much about TCAS, so I'll read up on it .....

Its useful for a pilot to get the 'inside' info from ATC, I totally understand that there is no need to cause a missed approach by use of the transponder, its just no one has ever explained this before.

Cheers
EA:)

[Chilli Monster]

EA

Ahh - a misident - you didn't say that did you. That brings a whole different slant on story and answer.

And no - your 'racing' the aircraft on the ILS won't set it off because you're not on a track which will cause a conflict - you're ahead and staying ahead.

CM

[AMEX]

Not a bad tea ;)

[NorthSouth]

avard:

Stumbled across your question from July last year today and was a teensy bit surprised that no-one has pointed out to you that flying IMC 5nm east of Sheffield without a radar service is not terribly sensible. See those blue chevrons on the chart, extending to 7nm east of Sheffield? That means there's an instrument approach procedure there in uncontrolled airspace. the procedure may extend a good deal further out than 7nm. The idea of putting those on the map is to try to encourage folks like you not to fly through them.

You can do it at Sheffield now though - the IAPs have been withdrawn.

[flyingwysiwyg]

How does TCAS work then?

It seems to be a lot more clever than I first thought.

I thought that if it bounced its signal off a transponder and that transponder was too close it lit up like a Christmas tree and whooped!?!

Obviously there's more to it than that.

FWyg

[andrewc]

flyingwsiyig

I can only talk for the Skywatch that I've got in my plane.

It generates secondary radar interrogation pulses which
trigger local transponders in other aircraft to respond as
if the trigger were from a radar installation.

The Skywatch has a pair of aerials which triangulate the
incoming responses, stir in the response signal time
of flight, to get a picture of the aircraft (with transponders)
in the immediate volume of the source aircraft.

Over time (a few seconds) the TCAS builds up an idea
of where everyone is going and whether any aircraft
are on closing paths with the source aircraft.

It then issues alerts to the pilot to allow them to take
avoiding action.

Airline quality kit will talk to the TCAS in the other aircraft
to ensure that their respective avoiding actions will not
make the situation worse - as long as the crew obey the
TCAS instructions...

-- Andrew

[rodan]

flying IMC 5nm east of Sheffield without a radar service is not terribly sensible. See those blue chevrons on the chart, extending to 7nm east of Sheffield? That means there's an instrument approach procedure there in uncontrolled airspace. the procedure may extend a good deal further out than 7nm. The idea of putting those on the map is to try to encourage folks like you not to fly through them.
I disagree. If he was flying through the final approach track for the active runway at Sheffield, and was talking to Sheffield Approach, and was passed timely and accurate traffic information regarding traffic making an approach, then I would suggest the system worked perfectly. The blue chevrons are not there to say 'Don't fly here!', rather that it is sensible to be talking to the associated ATC unit if you intend to do so, for obvious reasons.

Radar is not the be all and end all. Granted, procedural ATC has no idea if there is unknown traffic in your area, but they are just as capable of separating you from known traffic as a radar unit is.

[flyingwysiwyg]

andrewc,

Thanks for that. Good explanation. :)

FWyg