Fog And 8 Octas

[richie-rich]

hey all
i know its a stupid question and one I should have asked my instructor long back. But I really havent and was wondering if someone could clarify this.

I remember flying to Dusseldort in Emirates A310-300 last year and the whole approach was in Nil-Visibility and 8 Octas. When coming back to Oz, we were diverted to Adelaide from Melbourne due to "extreme" fog.

Question is, how did we land in Dusseldorf in the first place in such an inclement weather whereas the scenario in Melbourne was 8 Octas and no thunderstorm?

Is it because Melbourne isnt set up for ILS fully whereas Dusseldorf is? Silly question for you all. Nevertheless, I wanna get this out of my mind.

Take care all
Richie

[simfly]

Richie,

There are different categories of ILS. The basic, cat1 allows a descent to approx 200 feet above threshold, with visibility down to a minima of around 500 metres. The more precise is cat 3, where you can more or less put the thing down (or the auotopilot will!) down to a height of 0 feet and and RVR of just a few metres!! You confuse me a bit going on about octas. This is just a meaurement of how much of the sky is covered. You could have 8 octas (or overcast is referred to mostly) at 1000 feet, or the same at 100 feet, neither would be classed as fog, which means visibility less than 1000 metres. I'm sure melbourne has an ILS, but whether or not you could land depends on how low the vis is, the ILS equipment and ALSO what equipment the aircraft has. You could have cat 3 ILS equipment on the airfield, but the aircraft (and crew) may only be cleared for cat 1/2.

Hope this clears things a bit.

Simfly

[richie-rich]

Simfly
Thanks for your reply, Sir. I am doing my P.P.L and am about to take the flight test. So, yes, I have a long way to go before I get to know ILS.

The thing that surprises me is the fact that an airport as big as Melbourne isnt equipped with cat3 ILS. Cant really blame the aircraft nor the crew as we flew a B777-200.

So, if there's a case where the airfirld isnt setup for a cat3, the flight has to be directed to an alternate aerodrome fitted with cat3, or move onto an airport where visibility, weather is comparatively better. Is this the case? I suppose it is.

Richie

[redsnail]

No airport in Australia is rated any lower than Cat I. The reason? Cost.

[northwing]

It's not that Australian airports are cheapskates, but there is always a trade-off between spending money on installing the kit and the cost of delays and diversions. In a nice sunny country like Australia the number of days when you can't land in Cat 1 conditions is relatively few and it is cheaper for all concerned to put up with the occasional delay than to shoulder the cost of installing and calibrating the higher Cat airfield equipment, not to mention the cost of equipping the aircraft and training the crew. In the UK it is claggy much more often and the economics are different.

The other side of the equation is the availability of diversion airfields and their weather patterns.

[5milesbaby]

It can be the case too that the aircraft can autoland (nil metres viz), that the airport has CAT IIIc, and full procedures are in place to allow autolands, but the CREW cannot. This comes down to training and experience of the crew basically, and does happen. :ouch:

[richie-rich]

hey 5milesbaby
thanx for your reply. r u telling me that a 777 captain cant land a plane under cat3 procedure just coz he wasnt trained to? i thought its basic IR stuffs!!

If thats the case, what happens when the ATC advises on Cat3 procedure in process and ask the crew to make a 0-visibility approach? Do they just say "Errr.....no, i aint trained for this stuff?" That sounds ridiculous to me.

Any thoughts?
Richie

[FlyingForFun]

Richie, I remember a case like this in the news a few months ago. I'm sure there were threads about it, if you go back through the archives.

I think it was one of the budget airlines, flying from up north somewhere to one of the London airports (my memory of the details is a little hazy!) The first officer had recently joined the company, and as such hadn't had a chance to do the company's CAT3 training yet. That wasn't considered a problem, since the forecast was good, but the forecast was wrong and CAT3 conditions existed at the destination. The aircraft diverted to the Midlands somewhere, and the airline flew in another (CAT3-trained) crew member who was then able to fly the aircraft and pax to its original intended destination.

FFF
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[lizbet]

Richie,

It's possible that a newly qualified captain may not be allowed to do CAT 3 or likewise a crew with the F/O in training. Also each pilot is responsible for maintaining currency by performing at least one practice Cat 3 autoland in the last 6 months - plus one in the sim. Sometimes it's forgotten or you can spend a month only going to Cat 1 capable airports or even normally Cat 3 capable airports/runways where the equipment is downgraded due to maintenance.

Schiphol, Amsterdam often has ILS's operating at less than CAT3 - and if the system is below a certain level of accuracy (published in notams) you are not allowed to do an autoland and therefore it is difficult to maintain currency.

[richie-rich]

I am stunned! i thought you are taught all these when you are doing IR. So, is it like an acquired skill? When airlines are so stringent about recruiting pilots, why dont they pay heed to this aspect?

FlyingForFun, i understand that the first officer was incompetent to fly a Cat3 procedure. What about the captain? with all those years behind him?

Gosh!
Richie

[Bealzebub]

No need to be stunned Richie, you just don't understand what you are being told.

Category 2 and category 3 approaches require "special" crew certification and "special" aircraft certification. In order for an airline to operate to the much lower limits that these categories allow for, both criteria must be applied.

In order to operate to Cat 3 limits which are often around 14ft decision height and 75 metres visibility ( as opposed to the normal non special category 1 limits of 200 ft decision height and 550metres visibility ) The aircraft has to have multiple systems working that might otherwise be allowed to be partially unserviceable. For example both caprtain and First officer have in front of them something called a mode status annunciator. It shows if the aircraft can complete a category 2 or category 3 approach. Ordinarilly it doesnt matter much whether one or both or indeed either are working, but for a category 2 or 3 approach the First officers must be serviceable. It is exactly the same as the Captains, but his can be unserviceable the first officers must be working. There are many other examples of equipment that must be working for a Cat 2 or Cat 3 approach that are not required for a Cat 1 approach.

Crew requirements involve additional training and simulator practice. There is also an experience requirement. a new F/O or Captain may not be able to operate to cat 2 or cat 3 limits until they have completed a requisite number of hours on type and a set number of practice autolands. In addition there is a requirement to maintain currency normally 3 actual or practice autolands in 6 months. If this isn't done the currency lapses.

As well as aircraft special requirements and crew special requirements there is also Airport special requirements. The airport must have a certified Cat 2 or cat 3 Instrument landing system. As well as this the airport must have special proceedures in force to protect the integrity of the cat 2 or cat 3 ILS signal. If any one of the special additional requirements are not serviceable then Cat 3 or Cat 2 may be out of the question.

I have tried to answer your question as simply as I can. There are many things required in addition to Cat 1 requirements that are needed to operate a cat 2 or cat 3 approach. it has nothing to do with people being incompetent or paying heed to experience or being taught an Instrument rating. Given your low level of experience this is not a simple subject to understand, but I hope this sums up what the other contributers have already stated and gives you a basic understanding of the concept.

[richie-rich]

Dear Bealzebub
Thank you for your post. Yes, I am a rookie compared to you guys, as you already know. I just wanted to know the reason for which flight crews would fail to land an aircraft at 0-visibility and you have summed it up well and so did lizbet, FlyingforFun and the rest.

There is so much to explore and to learn in this fascinating world of aviation! sorry if I have kicked you guys with silly questions, but as I said, I was curious and now that you have answered my question, I am thankful to you all.

Richie

[FlyingForFun]

Richie,

To add to Bealzebub's reply, you said you: "thought you are taught all these when you are doing IR."

I doubt that any aircraft which is used for initial IR training is capable of doing a Cat 2 or Cat 3 approach, although I may be proven wrong. No, it is certainly not taught as standard.

Hope that helps - and there's no such thing as a silly question!

FFF
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[Bovey]

richie,

bearing in mind the technical side that has already been explained very well to you, to add an extra to I just wanted to know the reason for which flight crews would fail to land an aircraft at 0-visibility another reason is that CAT3C is really only a theoretical possibility. Why? Well all the technical systems both a/c and groundbased could allow it, but once the landing roll is finished it's back to good old mark one eyeballs out the window to taxi to the gate......somewhat difficult in 0 vis. Most operators work on a mimimum vis of 75m for a CAT3B with either no decision height (ie the mainwheels touch the ground with no requirement for the crew to see a visual reference) or with a decision height of something like 14ft where some visual reference (one light!) must be seen to continue (you will touch the ground in the go-around in this case if you do not see the reference and elect to go-around.)

You also mentioned that you thought this was pretty basic stuff that would be taught at IR. Quite the contrary, this is more advanced and could not be taught on a light aircraft during an IR. The LVP (low visibility procedures training) teaches the roles of the two pilots during these operations and the suitable actions in response to downgrades in the a/c or ground equipment. These operations are considerably different from normal (hence why BA use the 'monitored approach' on every approach so LVPs are no different.)

Changes in company or movement from right seat to left seat do not preclude normal operations once the basic conversion training has been completed, LVP training may not be scheduled or completed immediately for various reasons therefore the 'tick in the box' legal requirment will preclude an LVP approach. Nothing to do with incompetence (on the part of the pilot!)

Hope this helps.

PP