ILS Categories. Do I have the right idea?

[englishal]

Synthetic vision actually gives you a tunnel when the approach is activated. You intercept the tunnel (if vectors), stick the momentum marker in the middle of the tunnel, and you will land on the runway. traffic appears on the Synthetic vision too along with any other pertinent info.

It is pretty funky when this if from a GPS LPV approach, and makes you realise what really is possible these days (unfortunately not in Europe for another 20 years).

I'm all for anything to aid situational awareness. My buddy flew into a mountain on an IAP in a Seneca, obviously lost SA and killed 5 people. GUARANTEED if he'd been flying one of these aeroplanes, this would definitely not have happened.

The problem is when that person goes beyond the limit and pushes their luck.....

[mad_jock]

But there is no calibration of the information.

You have no way of knowing if its correct or not.

[mm_flynn]

Originally Posted by mad_jock

But there is no calibration of the information.

You have no way of knowing if its correct or not.

???
which information?

the 'tunnel' is either going to be generated from an LPV Or VNAV representation from the GPS, or I believe from the ILS data. Either way this is going to be 'right' to well below Cat I DH.

I accept there may be a risk that for some airport the runway placement may be in error (certainly with regard to trying a blind landing). And is, as far as I can see, the main risk with SV.

[mad_jock]

If your using it as signal generator to display an alternative to cross hairs or "wings" for true ILS data fair enough the terrain data cant be trusted unless someone calibrates the ILS using the same info.

If your using it in GPS mode to generate a persudo VORTAC approach then flying it down the boxes with no error flagging or secondary cross check of GPS error you need your head examining.


Although quite whats so hard about getting two needles to form a cross I really don't know.

[riverrock83]

My understanding is that with current technology (WAAS - so only in the USA), GPS can't be relied upon to be more accurate than +- 7.6 meters at least 95% of the time (that is from the WAAS specification) horizontally and vertically. If you have a large commercial runway 45m wide (which is likely the case if there is an ILS available anyway) then you are still going to hit it. However without some way of determining height (ie a radar altimeter) then landing with your head down simply isn't safe (your guess when to flare is as good as mine!).
I believe WAAS allows GPS to be used for Cat I approaches in the US - but most of us on this forum aren't in the US.

Without the additional checking that WAAS provides you need to have some other way of verifying that your GPS is accurate.
Maybe once EGNOS is available it will be different. Until then GPS can only be a secondary navigational source in Europe.

[peterh337]

Until then GPS can only be a secondary navigational source in Europe.

Oh dear here we go again.



One thing which is so much better about pprune than Flyer is that the most useful icons are much better placed

[mad_jock]

Peter it doesn't change the fact its correct.

And in my experence when your flying in the crap is when the bloody signal drops out.

[maxred]

I honestly looked at the clock and thought, wonder if Peter has read this yet.

[mad_jock]

I know and either he has the best GPS installation in europe (which it well might be)

Or he doesn't fly in the crap that I do which is when normally it does give up the ghost.

And thats not even discounting the multiple bawbags around europe with illegal hand jammers and the fact that mutliple completely official agency's can jam with no warning whats so ever

[maxred]

Two weeks ago, 7500 feet over Carlisle, and lost GPS signal, for at least 20 minutes. The best of it was that Carlisle International had asked me to squak, and when I lost the signal, I asked Carlisle to give me a position check re Danger Areas, his reply being we are non radar

Just as well I knew where I was then, tracking my trusted RNAV

[englishal]

Although quite whats so hard about getting two needles to form a cross I really don't know.

You get the tunnel IN ADDITION to the regular needles of course.

[mad_jock]

So what do you need a tunnel for then? You either in limits or your not and going around.

All this extra stuff does is just over load the pilot with information and distract them away from the primary instruments.

[stickandrudderman]

People often advocate entering a long runway at half length in order to expedite departure. My own view is that it's foolish to throw away the opportunity to land back on in the event of an engine failure after takeoff, so I always start as far back on the runway as I can as it gives me an extra safety margin.
I like having SV and GPS in my aeroplane because it gives me an extra safety margin, not because I'm a lazy pilot who can't be bothered with situational awareness.

[Denti]

Synthetic vision is a very nice tool. However it can only display database info, not the car on the runway, nor the aircraft that switched off its transponder once it landed. And the database cycle is of course a major issue. Just judging from nearly every european airport there are always several NOTAMS out about new obstacles, work in progress with cranes and so on. Even at a normal update cycle length of 28 days (EGPWS databases do not update that often) there are always numerous obstacles that are not part of the database.

Now, enhanced vision is quite another thing. Costs of course quite a bit more, but then, it can do more too, even in europe you get lower limits with that.

[mad_jock]

enhanced vision is quite another thing

O yes that is an extremely nice bit of kit.

[NazgulAir]

People often advocate entering a long runway at half length in order to expedite departure. My own view is that it's foolish to throw away the opportunity to land back on in the event of an engine failure after takeoff, so I always start as far back on the runway as I can as it gives me an extra safety margin.

Reminds me of my instructor telling me about the three most useless things in aviation:
- the runway behind you
- the air above you
- the fuel in the bowser.

[peterh337]

in my experence when your flying in the crap is when the bloody signal drops out.

Perhaps you should post some pics of your avionics, MJ.

Hang on.... I think I have found it!!!!



Google is just wonderful.

[mad_jock]

I can't see the BRNAV gps in that pic peter. I don't think it would cause me any problems though. I fact I would love to fly it if its what I think it is.



Nope this is the avionics I had most drop outs with. But it didn't really matter because its primary mode is DME/DME cross cuts

[peterh337]

Nice as that looks, it is probably a pre-GPS-era cockpit.

[Piltdown Man]

Not just the numbers, but do I have the idea right?

Basically, yes.

What exactly is different with the different ILS categories except for the decision height? Speeds, etc. all remain the same?

The training, equipment, sometimes wind (due A/P limitations), DH, airport equipment and status, runways slope, RVR just to name a few.

Do you find the DH if you're doing CATII, or CATIII on the approach plate itself?

For CAT II, these are published on the plates we use but CAT III minima are operator specific. These are supplied by your company and come as a result of specific Low Visibility Operations training.

Is it ever possible that your RVR corresponds to a certain category, but your DH is too low for that ILS category?

I think you have this arse about face. Assuming you have a "standard" CAT III runway and an appropriately equipped and trained crew, the RVR defines the lowest DH that can be used and by virtue of that, the type of approaches that can be flown. So if the RVR is greater than 550m, a crew could fly a CAT I, II, IIIA or IIIB approach. Drop the RVR by 100m to 500m and a CAT I approach is (generally) no longer possible. Drop the RVR to less than 300m and a CAT III approach has to be flown.

Does that make sense?

PM