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Old 10th Aug 2012, 05:45
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EYZ
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LVO's

G'day All,

If you conducting a Cat IIIA approach to 50'/200m minima, what's the minimum RVR you require for the mid point and stop end?
Let's assume everything is working, such as roll out guidance etc

I thought you required 200 for all the segments, but now I'm told it's only 125 for the mid point and 75m for the stop end!!

Thoughts!
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Old 10th Aug 2012, 06:18
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LVOs are an individual state/operator authorization, so there will be variations.

For instance, the minimum CatIIIA minima my company operate to are 200M Touchdown, 125 midpoint, and Captains discretion as to whether a stop end RVR is even required, but with a minimum of 75m if he judges it is.

The 200m is required so that, from the 50' DH, enough of the runway can be seen to provide lateral guidance (3 consecutive runway lights) as roll out guidance is not guaranteed with CatIIIA..

Once on the runway, 125m is sufficient to keep straight (it is, after all, the same as the minimum CatC takeoff minima), and the assumption is you will be at low speed and only needing turn off guidance at the stop end (as you would if you were CatIIb, which has an absolute minima of 75m)

Yes, it's called "Minima" for a reason! It's JUST enough, but you can operate to it.

As to "I'm told", and "Thoughts", are you actually in an LVO authorised operation? if so, it sholud be in your manuals- no "Thinking' required!!

Last edited by Wizofoz; 10th Aug 2012 at 06:20.
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Old 10th Aug 2012, 06:42
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Good description Wiz.
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Old 10th Aug 2012, 09:39
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MID 125 is only required if manual rollout is intended or redundancy for rollout system isn't warranted CAT III SINGLE for the bus otherwise MID and ROLLOUT can be 75 provided CAT III DUAL is on FMA, for the bus. Mind you this is only applicable for EU OPS operators conducting LVO OPS in EU. USA, CANADA, OZZ is different.

as roll out guidance is not guaranteed with CatIIIA..
That's absolute bollocks Wiz. CAT III A can be conducted with NO DH. CAT III definitely guaranties rollout guidance. CAT II doesn't.
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Old 10th Aug 2012, 09:45
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CAT III definitely guaranties rollout guidance.

no, THAT'S Bollocks.

I have operated to CatIIIa with no rollout guidence (B737-300/700 specifically-the CatIIa options don't even have a rudder channel)

That's why you require the 200m vis- to establish lateral guidence.

Though in theory a it can have no DHnever seen a CatIIIa operation with a DH less than 50', To do so you must have an aircraft certified as Fail- operational- in other words any aircraft capable of CatIIIa No DH is basically capable of CatIIb.

From the Royal Aeronautical society:-

For Cat 3a operations involving the use of fail-passive automatic landing equipment, the minimum RVR which is
normally acceptable for operations with small or medium size aircraft is 300 metres. If the aircraft system
demonstrates an in-service record of high reliability, such that the probability of a system failure during the early part
of the landing flare can be shown to be very low, consideration may be given to a reduction in the RVR.

For Cat 3a operations using fail-operational automatic landing equipment which does not include automatic roll-out
control or guidance,
the minimum RVR is 200 metres.

For Cat 3a operations using fail-operational automatic landing equipment, with fail-passive roll-out control or
guidance, the minimum RVR is 150 metres.
My bolding.

Last edited by Wizofoz; 10th Aug 2012 at 10:05.
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Old 10th Aug 2012, 10:03
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In our outfit

CAT 2 requires a minimum DH of 100'
CAT 3A requires a minimum DH of 50'
CAT 3B requires a minimum DH of 0' ( ie no DH )

These are regulatory minimums and will vary between Airports as required.

For CAT 2 and CAT 3A touchdown and midpoint RVR's are controlling ( there are allowed exceptions for system failures )

For CAT 3B all 3 RVR zones are controlling ( this can be reduced to 2 in some circumstances as well )

Last edited by nitpicker330; 10th Aug 2012 at 10:10.
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Old 10th Aug 2012, 10:04
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I have operated to CatIIIa with no rollout guidence (B737-300/700 specifically-the CatIIa options don't even have a rudder channel)
That's aircraft's feature Wiz, we're talking bout ILS CAT III ground facility.
ILS CAT III ground facility does provide rollout guidance otherwise NO DH OPS would't be allowed on it. Yet it's common all over US to fly CAT III A with NO DH.

Though in theory a it can have no DH never seen a CatIIIa operation with a DH less than 50',
Well, check out the definition of CAT III A.
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Old 10th Aug 2012, 10:07
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No, YOU might have been talking about ground facilities, everyone else was talking the specifics of Aircraft operation.

I repeat and am correct- ROLLOUT GUIDENCE IS NOT A REQUIREMENT FOR AN AIRCRAFT TO BE CATIIIA.

Interesting that you claim to have only been talking ground equipment, while simultaniously banging on about the features of tha Airbus.....

Yet it's common all over US to fly CAT III A with NO DH.
Not in 737s it aint....

Last edited by Wizofoz; 10th Aug 2012 at 10:09.
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Old 10th Aug 2012, 10:33
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Wiz,
The 200m is required so that, from the 50' DH, enough of the runway can be seen to provide lateral guidance (3 consecutive runway lights) as roll out guidance is not guaranteed with CatIIIA..
There's no reference to the aircraft whatsoever. Never mind, CAT III A ground facility does guaranty rollout guidance. CAT III A certified aircraft under EU OPS doesn't require rollout guidance, that's correct. Other than EU OPS CAT III A with NO DH rollout guidance is required for obvious reasons. RVR requirements are different as well. Just pointing out that EU OPS is different from ICAO and FAA.
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Old 10th Aug 2012, 10:47
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We're getting into willy waving territory, methinks.

Perhaps better just to make your point and then retire from the argument if it starts to go around and around ?

If the point proposed is a matter of fact rather than opinion then, as one poster has done, it is simpler to cite an authoritative reference .. preferably with a link to an appropriate URL.
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Old 10th Aug 2012, 11:06
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If you conducting a Cat IIIA approach to 50'/200m minima, what's the minimum RVR you require for the mid point and stop end?
Let's assume everything is working, such as roll out guidance etc
Under EU OPS, if the aircraft has rollout guidance and redundancy is provided then MID, ROLL OUT RVR can be as low as 75 m. Without Rollout guidance and redundancy given RVR MID has to be 125 for the manual rollout.

reference EU OPS commencement and continuation of approach.
The touchdown zone RVR is always controlling. If reported and relevant, the mid-point and stop-end RVR are also controlling. The minimum RVR for the mid-point is 125m or the RVR required for the touchdown zone if less. The minimum RVR for the stop-end is 75m. For aircraft equipped with a roll-out guidance or control system, the minimum RVR value for the mid-point is 75m.
Table 14 CAT III OPS depicts required RVR dependable on type of approach and rollout guidance system installed. All straight forward.

Last edited by 9.G; 10th Aug 2012 at 11:07.
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Old 10th Aug 2012, 11:50
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Under EU OPS, if the aircraft has rollout guidance and redundancy is provided then MID, ROLL OUT RVR can be as low as 75 m. Without Rollout guidance and redundancy given RVR MID has to be 125 for the manual rollout.
I fly a 777 which obviously DOES have roll our guidence, yet the minimum CatIIIa vis we operate to is 200,125,75 with a 50' DH.

Why? Because the only time we are likely to be restricted to CatIIIa is if we carry an MEL or have an equipment failure which leaves us Fail Passive or without roll-out guidence- in which case the 50'/200m applies.

The OP specified 200,125,75 m and I gave the rationale for those figures in an Aircraft that does not have roll out guidence.

Perhaps I should have been more explicit for the sake of the pedants, but that doesn't make what I said Bollocks, and you, 9G, might consider your tone when addressing others.
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Old 10th Aug 2012, 12:16
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I fly a 777 which obviously DOES have roll our guidence, yet the minimum CatIIIa vis we operate to is 200,125,75 with a 50' DH.
Well, Wiz, I can't force you to take advantage of the current regs. I already quoted it for you, if you are fail operational even on CAT III A with DH 50 your MID RVR can be 75 M. No need to be cocky here Wiz, nothing posted by me is directed against you personally.

Why? Because the only time we are likely to be restricted to CatIIIa is if we carry an MEL or have an equipment failure which leaves us Fail Passive or without roll-out guidence- in which case the 50'/200m applies.
So I take it you don't fly to CAT III A only certified airdromes then? When we speak LVO it involves Aircraft, Crew, Airdrome, Operators Specs.

Last edited by 9.G; 10th Aug 2012 at 12:16.
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Old 10th Aug 2012, 12:57
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Well, Wiz, I can't force you to take advantage of the current regs. I already quoted it for you, if you are fail operational even on CAT III A with DH 50 your MID RVR can be 75 M
Only with specific approval. Ours is as I have stated.

need to be cocky here Wiz, nothing posted by me is directed against you personally.
Perhaps you meant "Utter Bollocks" in some new, polite way?

I take it you don't fly to CAT III A only certified airdromes then?
ALOMST certain the answer to that is no, and we fly to some 125 destinations.

When we speak LVO it involves Aircraft, Crew, Airdrome, Operators Specs.
Precisly so, yet you keep stating the absolute minimums as if they are unoversal.
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Old 10th Aug 2012, 13:03
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Old 10th Aug 2012, 13:55
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Wizofoz,

9.G is absolutely spot on with everything he says.

Cat 3a does not require 125m mid (as the ground based system assures rollout). Only if your aircraft has a degradation do you need to apply 125m instead of 75m.

I also fly the B777 for a EU-OPS compliant carrier and I think you need check again your airports. There are plenty of Cat3a only runways both in Europe and outside. Try Hannover 27R for starters. So when mid drops to <125m you divert while we land ? Commercially your company should look at this again,
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Old 10th Aug 2012, 18:43
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Wiz, I'm sure EK has thought it's OPS specs well through. Usually the confused ones are either upgrade candidates or management folks. No offense intended just a mere observation. As you pointed out EK flies to 125 destinations worldwide. So next time you fly to MEL have a look at your plates for ILS 16 X CAT II & III approach chart. You can convince me with 2 pints on CAT III A min 200/125/75 theory there.

Last edited by 9.G; 10th Aug 2012 at 19:30.
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Old 10th Aug 2012, 20:00
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8ache,

I didn't say he was wrong.

Just that I wasn't either.

9

Our MEL approach plates (Lido) say "Cat 3b Company".

Our CCI LVO pages then give Cat3b 0', 75,75, Capts discrection and Cat3a 50', 200m, 125m, Capts discretion.

I accept no offence was intended, but understand that "Utter Bollocks" is not the most polite way to voice disagreement.

Yes, everything you have said is correct, but it was still a pretty abrupt input when all I was doing was explaining the rationale to the OP, who specified 200,125,75, as is usual when roll-out guidence is not available.
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Old 10th Aug 2012, 20:18
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aren't we talking CAT III A here? CAT III A for MEL states 175 M, doesn't it? Just trying to make you aware of the differences. Now you tell me, what are the requirements for MID and ROLLOUT on CAT III A in MEL RWY 16?
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Old 10th Aug 2012, 20:27
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I just told you- Our minimas for MEL RWY 16, CAtIIIa are a 50' DH, with 200m TDZ, 125m MID and Captains Discretion down to 75m RWY end.

Would you like me to email you the chart?

We also have CatIIIb there, 0'DH, 75,75,75.

Lido charts don't state anything about CatIIIa if CatIIIb is available- they just refer you to company minima.

COULD IT BE we have different approved minima than what you were aware of??

Last edited by Wizofoz; 10th Aug 2012 at 20:30.
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