What do I need to know, GCA?

[John Hill]

Our Link Trainer project is moving slowly along and now it has been suggested that we offer GCA (ground controlled approach).

As the project stands the pupil will have an instrument panel in the trainer and he/she will actually be flying MS Flight Simulator (MSFS) behind the scenes. The instructor will have a duplicate of the instrument panel and will also have the regular MSFS displays.

Now the notion is the instructor will use MSFS GPS display to provide simulated area radar and the MSFS ILS instrument to provide GCA and talk down the student. I wonder what we are forgetting?

As an alternative the instructor could us the MSFS pilot's view display and provide GCA from interpretation of the VASIS.

Just to be clear, the instructor has full MSFS displays and the student has only the instrument panel. The instrument panel is not a duplicate of the MSFS display but is a simple display and restricted to WWII era instruments.

We are able to include things that were never in the WWII Link Trainers, for example we can pause the action while the instructor explains what is coming next (I am not really sure they could not do that!). We can also swap out the instrument panel for a view outside, for example at decision height we can quickly swap the instrument panel to a view ahead so the student can land, or go around.

Any insights in to GCA greatly appreciated!

[Ex-Ascot]

Do you mean PAR or SRA?

[Rwy in Sight]

I think there are two different radars working together. One for the bearing and one for the attitude.

I am not sure it answers the question.

[Ex-Ascot]

I think there are two different radars working together. One for the bearing and one for the attitude.

I am not sure it answers the question.

That is PAR. Precision approach radar.

[John Hill]

I thought GCA was the original term (American?) for radar approach guidance with a ground operator, or two.

My concept is that the Link Trainer instructor will have the regular MS Flight Simulator display and will interpret the VASIS and/or ILS to give 'UP', 'DOWN', 'LEFT', 'RIGHT' instructions. I have not been able to find a list of phraseology that was used, that sort of things.

Somewhere in my darkening memories is a film I saw with two ground operators, once watching glide slope and the other lateral CRT displays. They were little 3 inch round thingies.

SRE, IIRC is the equipment which allows a ground station to provide SRA (I think). I thought we might offer that to the Link pilots also as we have a GPS display.

Is PAR pilot interpretated? If not, how is it different to GCA?

Any general enlightenment of this topic and related stuff much appreciated.

P.S. I just found some of the stuff I am looking for.. https://skybrary.aero/articles/precisio ... -radar-par

[Boac]

This may help?

[John Hill]

Thanks, I do not see how that is different to GCA. I think we will be able to train a few 'instructors' to give that 'talk down'.

Bear in mind that our student will have nothing to look at except the instrument panel until about 200'(?) at which point we will pause the simulation and switch to a forward view. Time will tell.

[Boac]

I do not see how that is different to GCA

You are confused, John, by the muddled language of the USA. Stick with good old 'King's English'? Ex-A pointed this out to you 'upstream'. ANY approach to an airfield that is not controlled by the pilot is a 'GCA' - that includes radar vectors, a QGH or other approaches. I understand you wish to implement a 'Precision Approach using PAR (Precision Approach Radar) as opposed to an SRA (Surveillance Radar Approach) which uses SRE (Surveillance Radar Equipment)? Decision heights normally being 200' and 600' (?) respectively. I never experienced a USAF 'SRA' so I don't know if they ever did them.

The RAF PAR approach was usually so good that one could actually get students to fly on instruments to touchdown having asked the controller to continue to talk to touchdown - which was contrary to their 'rules' which used to terminate at 200' ATE, so they had to be asked to do it 'for practice' to cover their arses

There are several instances of aircraft actually being talked down onto the runway for real in bad weather. The RAF controllers were excellent. USAF controllers naturally used to emit 'standard BS' on their talkdowns - "You are 5' above the glidepath and 4' left of the centreline' - but all taken in good spirit.....

[Ex-Ascot]

Boac describes the two well there. Just to add that with a SRA you are just guided onto the centre line and given distances to touch down. You work out the altitude you should be at from that.

Any airfield with surveillance radar should be able to give you a SRA. Indeed we once did a SRA into Warton, I think, using the surveillance radar from a nearby airfield. We made up our own DA (MDA ?) which is variable dependent on obstacles. Not legal of course but we were under some pressure to get in. A lady you do not upset who says it how it is. We had already been diverted from Liverpool due to a suit case on the runway! They blew it up. There were knickers and bras floating down the Mersey for a week.

Pilots going into NHT always used to ask for Mrs Ex-Ascot for a PAR. The voice and accuracy. If they knew that in uniform she always wore black stockings and suspenders I am not sure if all results would have been so successful.

On a few occasions she was asked to keep talking below DH.

[Boac]

You work out the altitude you should be at from that.

Not in my experience, Ex-A - ATC gave the advisory heights with ranges. This (possibly CAA/MATS?) video explains it.



I do hope Mrs Ex-A always let you down gently...................

[PHXPhlyer]

To distill it down a bit:
As Ex-A said: PAR Precision approach, think ILS, Decision Height (DH).
SRA Non-precision approach, think VOR/NDB Minimum Descent Altitude (MDA)
I was able to have experience with both during flight training as an Army Air Base was nearby, low traffic, and controllers needing practice to maintain currency.

PP

[llondel]

Arthur C Clarke had a PAR description in his novel "Glide Path".

[Ex-Ascot]

Boac yes I am sure you are correct come to think of it. Didn't do many.

[John Hill]

I am afraid it is unlikely that I can persuade any of the fair sex to do a turn as our instructor but I does remind me of the the time (1982?) when I met the voice of London Volmet, if I recall correctly his name was John West and had a perfectly controlled 'military' (RSM maybe) voice. Marconi were trying to sell the system to NZ but that was not to be. $$$$!

Some years later I was working out in a small company and I wrote a system for ATIS, VOLMET etc. My system used pre-recorded words and phrases and the hardest part of the project was finding someone who could record several thousand words and phrases in a perfectly controlled voice that could be seamlessly grafted into a broadcast. We found a young lady with the mannerism of a librarian and I was rather pleased with her voice. A few weeks later I was baled up by a Boeing driver at a social gathering, he said "I hear you made that ATIS? Well I am fully tuckered out flying all day listening to that angry b...h!"

It seems they did not like our nice lady and had recorded with one of their own, a women who was a new arrival in NZ, oh dear, it would be racist for me to say more on that. We had another sound library with a man's voice and the client was persuaded to use that.

This was one of the first software projects I did and it stayed in use for many years, maybe even still going on Auckland VOLMET, possibly other countries too in Asia, Africa, Europe. It was/is also used for broadcasts to shipping around NZ and Oz.

You might have also heard my work elsewhere as an aeronautical organization in Europe asked for a description of our product which they then used in a tender proposal for someone else to produce.........!

[John Hill]

I do not see how that is different to GCA

You are confused, John, by the muddled language of the USA.

Oh dear, a consequence of living just across the pond from them. To be honest I am somewhat disgusted at the americanization processes in NZ, our TV channels are full of it and it seems almost impossible to buy a tractor now in any colour except green. Our Skippy ANZAC mates have long ago stopped building utes so all farmers and trades people now drive veritable lorries and pantechnicons to the supermarket.

[Ex-Ascot]

Yes John I remember the time when the Brussels VOLMET was the one to listen too. A very sexy voice.

You can be fooled though. I was operating into Harare once and the lady on HF sounded very nice. Went to see her. Must have been something to do with the distortion on HF. She was very pleasant but rather large shall we say.

[John Hill]

I do not remember listening to Brussels VOLMET but I did listen to a lot of them, as many as I could hear from NZ. I listened to one of 'mine' where they had re-made the vocabulary library and they had made a real pig's ear of it!

We were setting up AFTN, ATIS,VOLMET and NOTAM data base in Prague and we came to the stage where they needed to make the library but they were reluctant and thought they could use the library we already had but I explained it needed to be someone who could speak English and was familiar with the Czech place names. "What about that lady on the fourth floor?" I said, "She speaks good English, she might even be from England." There was a pregnant pause until someone explained "She is not English English, she speaks Moscow English"! No way would she get the honour of Voice Of Praha VOLMET!

[John Hill]

You can be fooled though. I was operating into Harare once and the lady on HF sounded very nice. Went to see her.

When I was still with Civil Aviation Department three of us went on a tour of inspection of all the NZ airports where we had staff in my department, a dozen or so of the smallest manned airfields pretty much in what the Ozzers would call 'Outback'. We went to one place on the West Coast for a few hours then flew back to Christchurch in the departmental Cessna, over dinner our pilot asked "How many staff do you have at West Port John?" "Just the one" I replied, "Lorainne, you met her." The chap was obviously confused and asked who was the man on the radio. Oh dear, Lorainne was formerly known as Sidney!

Lorainne passed on many years ago but I could still write a book on the adventures of having Lorainne in my department...