How do other airlines deal with SOP/callouts on Cat I

[oicur12.again]

Hey all,

I have just completed sim training at my new employer.

I was wondering if I could get some insight into how other airlines employ calls and procedures at the minima for a Cat I ILS approach.

My airline SOP proceeds thus:

1. PM calls “approach lights” when seen anytime, usually around the minimum.
2. PF responds with “continue” while remaining heads down on the clocks.
3. PM calls “runway” not later than 100’
4. PF calls “landing”.

FAR 91.175 lists several requirements needed prior to descending below the DA/DH/MDA, one of which is:

2. “The flight visibility is not less than the visibility prescribed in the standard instrument approach being used”

Our procedure does not provide for, nor is it taught, that at some point prior to continuing the approach, the flight visibility must be assessed to meet or exceed the visibility prescribed on the approach chart.

Seeing the approach lights at 200’ and the runway at 100’ is great but the PF should be provided with an opportunity to assess the vis before calling “continue”.

I have been chipped several times for not calling “approach lights” until the minimum auto callout but if I make the call before the mins, I cannot assess the viz because I have not yet seen the decision bar on the ALS. Not to mention we keep tripping over the autocallouts in marginal viz.

I am keen to know if other airlines overlook the need to assess the viz and also if other airlines permit the “approach lights” call, or equivalent, to be made at the minimum on marginal approaches?

Regards

[Intruder]

The "flight visibility" referred to in 91.175 is the reported visibility from ATIS, AWOS, Tower, or other ATC/FSS facility, and must be met to begin the approach. Once you get to the DA/MDA, the "visual reference" criteria of 91.175.c.3 apply, per your SOP.

Assume the reported visibility was sufficient when you commenced the approach at the IAF or took your first vector to intercept the approach. You can assume that visibility is still valid unless ATC specifically tells you (or broadcasts on your assigned frequency) the visibility has been reduced. Once you pass the FAF, you can continue to the DA/MDA regardless of any reduction. You can then assume the actual visibility is sufficient if you meet the "visual references" requirements -- THAT is your assessment.

[oicur12.again]

Intruder,

Your post is appreciated.

I think my instructor’s opinion is in line with yours and it certainly is a practical approach to take.

However, if you read the attached document from the FAA website, it states:

“How do you determine flight visibility when coming out of the clouds on an approach? If the approach has a lighting system, there are a number of clues in the system itself.
• Decision bar. Every approach lighting system has a "decision bar" located 1,000 feet from the runway threshold. These lights (or bar) are perpendicular to the approach lighting system.
• "Rabbit." There is another 1,000 foot clue in the sequenced flashing lights, known to pilots as the "rabbit." The sequenced flashing lights stop at the decision bar.
If you are at the middle marker (MM) and you cannot see the runway threshold, look for the decision bar. Assume that you spot the decision bar. If you know that the MM is six tenths of a nautical mile (0.6) from the threshold, then you have 3,650 feet from the runway. Subtract the 1,000 feet from the threshold, which you cannot see, to the decision bar, which you have spotted, and that leave 2,650 feet -- just under 1/2 mile. If the minimum visibility for this approach is 1/2 mile, then you have the required visibility.”

https://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=17273

This above reference to a “decision bar” and how to “determine flight visibility” leads me to believe that the FAA intends an assessment be made at the DA/DH/MDA regardless of the reported viz from ATIS, AWOS, Tower.

[Radu Poenaru]

Visual assessment of visibility at minima (using complicated arithmetic nonetheless) is not required to descend below DA/MDA. Having visual reference on one of the 11 or so listed items (als/thrshold lights/etc) is.

Granted, the wording on the website is misleading and could easily be misinterpreted, but this is basic IR stuff.

I suppose they are really trying to give you a (clever?) method of "estimating" visibility based on the ALS properties, so you can look smart to the Capt and say "yeah, looks like we have 2635' of visibility".

ok, later edit:
after reading that whole page one more time: It is definitely written in a way that suggests visibility at minima is a requirement before descent.
At least in EASA-land,regs make this a bit less ambigous:

" CAT.OP.MPA.305 (d) If, after passing 1 000 ft above the aerodrome, the reported RVR/VIS falls below the applicable minimum, the approach may be continued to DA/H or MDA/H "
" CAT.OP.MPA.305 (e) The approach may be continued below DA/H or MDA/H and the landing may be completed provided that the visual reference adequate for the type of approach operation and for the intended runway is established at the DA/H or MDA/H and is maintained."

Kinda happy to have found this, as it is probably the only time I have ever seen EU-OPS be easier to understand than FAR !!

[bigduke6]

I place emphasis further down the FARs to 91.175.c.3.i

"(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.

So for the US operators that I have worked for:
PM calls what he sees when he sees it, ie "approach lights"
PF, prior to mins, says "in sight, continue"
PM or auto callout of "minimums"
PF, "continue" if just app lights in sight, or "landing" if rwy is in sight.

For Cat I ILS, you are continuing below the 200' Cat I mins using the approach lights, and hopefully, when you get down to 100' you will have the red terminating bars or the rwy and adequate vis. But you are assessing the vis at 100', not at the 200'minimums. In a lot of cases, you will not have the vis at 200' if all you can see is the approach lights, but will have it at 100'.

[MD83FO]

to add more spice, if you're on an A320 would you keep the AP down to 100' waiting for the HIALS red terminating side row bars CAT 3 DUAL displayed on FMA.

[Meikleour]

MD80FO: you naughty boy!!!!!

[MarkerInbound]

"Flight Visibility" is not the reported metar or RVR. As defined in FAR 1.1, flight visibility is how far you can see from the cockpit of an aircraft in flight. So if you see the airport or the approach light lights three miles out, you have three miles flight visibility. At 200 feet on a three degree GS if you can just see the end of the runway you can see ~3000 feet or about half a mile. So you're good to land.

[GlobalNav]

"The "flight visibility" referred to in 91.175 is the reported visibility from ATIS, AWOS, Tower, or other ATC/FSS facility, and must be met to begin the approach. Once you get to the DA/MDA, the "visual reference" criteria of 91.175.c.3 apply, per your SOP."

"Flight visibility" is NOT "reported visibility" though it would not surprise me if many pilots treat it as such. Reported visibility is what the Tower observer sees or what the RVR transmissometer measures - essentially a MET parameter.

If you refer to 14 CFR Pt 1 Definitions - you will find "flight visibility" and "ground visibility", the latter of which more closely resembles "reported visibility".

quote: "Flight visibility means the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. "

quote: "Ground visibility means prevailing horizontal visibility near the earth's surface as reported by the United States National Weather Service or an accredited observer. "

Per 91.175(c), the pilot must determine that the flight visibility is no less than the visibility required by the SIAP.

[qwertyuiop]

I have never understood why some people make flying so dam difficult!

[oicur12.again]

Marker/Globalnav

I think I am on the same page as you.

On 2 occasions in my career I have seen NOTAMS issued temporarily raising the required viz for a CAT I ILS (probably some problem with the ALS).

On both occasions in briefing it became evident that the PF (captain on one occasion and FO on the other) was simply going to rely on the company SOP of sighting the approach lights at the minima in order to continue the approach.

Company SOP's are great but they do not help in such a situation, you still must assess the viz is above the min required.

[Intruder]

This above reference to a “decision bar” and how to “determine flight visibility” leads me to believe that the FAA intends an assessment be made at the DA/DH/MDA regardless of the reported viz from ATIS, AWOS, Tower.
Yes...

As I indicated earlier, looking for the "visual references" to the runway IS that assessment of flight visibility. You are not required to count lights to see if you have the appropriate number in sight. You merely have to have the environment (e.g., approach lights) in sight at the MDA/DA, and the "runway" (as defined by the red terminator bars of the approach lights, runway lights, threshold lights, etc) at 100'.

While I may have misspoken about the reported visibility as being equal to the flight visibility, it is still the reported visibility that controls whether you can BEGIN an approach, as well as whether you must discontinue an approach if it is reported to be below minimums before you get to the FAF. Once you pass the FAF, you can proceed to the DA/MDA regardless of reported visibility, and you make your "assessment" of flight visibility via the visual references at and below the DA/MDA.

That is why the PM's callout at DA/MDA is usually "Minimums" and the PF's response either "Go around", "Landing", or "Continue", depending on the visual references [not] in sight at that time. The PM should be scanning for those visual references throughout the final approach, and looking in earnest starting at 200' or so above minimums. The PM then 'calls 'em as he sees 'em': Rabbit, approach lights, terminators, threshold, runway, etc, as appropriate. The last 3 are included in the defined "runway" environment, which will allow the PF to respond "Runway, Landing" after a "Continue" call.

[AerocatS2A]

I have never understood why some people make flying so dam difficult!

Yeah. Can I see enough to safely land or not? If yes, continue, if not, go around.

[Radu Poenaru]

Company SOP's are great but they do not help in such a situation, you still must assess the viz is above the min required.

Would you let it go already. As you have been repeatedly told: those NOTAMS's new (reported) vis. will control whether you can begin/continue the approach beyond FAF/(1000' AAL). Not descending beyond MDA. There is no way to asses a 1700m visibility, in flight, when you are 15 seconds away from hitting the ground.

Can you honestly say that you will spot the runway in front of you at minima, and after counting the number of lights and determining you don't have the required visibility you will perform a go-around? while seeing the runway in front of you?

[Amadis of Gaul]

I have never understood why some people make flying so dam difficult!

Amen. It's really not rocket surgery at the end of the day.

[A Squared]

First, if you are on a CAT I approach have any of the elements listed in 91.175 (b)(3) in sight (except (i), the approach lighting system) you *DO* have the required flight visibility. Minimum vis for a CAT one approach is 1/2 SM/2400 RVR. All the elements listed in 91.175 (b)(3) except (i) are at the runway threshold or beyond. If you are at 200 ft on the glideslope, you are slightly more than a half mile from the runway, so if you can see them, by definition, you have more than a half mile flight visibility. Even on a non-precision approach, if you are in compliance with 91.175 (b)(1), then you are more than 1/2 SM from the runway at MDA.

Now, it *is* theoretically possible to have the approach lightning system in sight at 200 ft, or the red terminating bars in sight at 100 ft, yet not have 1/2 mile flight visibility. I don't know of a reliable method to determine that you don't have 1/2 SM flight visibility in the 8 seconds that it takes to descend from 200 ft to 100 ft on the GS. If I get the approach lights in sight at 200 ft, and the threshold in sight at 100 ft, I'm willing to consider that close enough to the intent of the regulation, but that's probably not an answer you like. FWIW, I don't recall ever continuing below the DA on the approach lights without subsequently picking up the VASI/PAPI before 100 ft, which would be about 1/2 SM.


But, the whole continuing to 100 ft below the DA introduces a grey area, as is contradicts the rest of the regulation. If you get to 200 ft and you have the approach lights in sight, but you do not have the terminating bar or side row bars in sight, you have not determined that you have 1/2 SM visibility, so at that point, continuing below DA as per 91.175 (b) (3) (i) is inherently a violation of 91.175 (b)(2)

Given that those portions of the regulation are inherently contradictory, it seems reasonable to assume that the intent is that having have the specified visual references in sight is more important that the flight visibility, which is difficult to reliably determine.

[oicur12.again]

Radu

“will control whether you can begin/continue the approach beyond FAF/(1000' AAL). Not descending beyond MDA.”

Yes, that’s true; the NOTAM will alter the requirements of the approach ban. That’s not what I am getting at though.

“Can you honestly say that you will spot the runway in front of you at minima, and after counting the number of lights and determining you don't have the required visibility you will perform a go-around? while seeing the runway in front of you?”

Yes, in theory that’s exactly how it should happen. Simply seeing the runway in front of you at the minima does not mean a landing can be continued, unless of course you assess that the requirements of 91.175 have been met. In most cases, yes, you will have sufficient in-flight visibility to continue below the minima if you see the runway, but not always.

Is it practical to make this assessment at the minima in marginal weather? No, which is why it’s a good idea to know exactly what you should see to satisfy the requirements of paragraph 91.175 part 2 prior to commencing the approach. You should know what you will see before flying the approach: decision bar only, runway threshold, touchdown zone or farmer Joes shed halfway across the airport.

In marginal weather, it is practical to assume that paragraph 2 will be satisfied by sighting the approach lighting system, as alluded to by A squared.

AOPA published a fine article about it with a point pertinent to this discussion:

“…..you can determine how many additional light bars beyond the decision bar you need to meet the minimum flight visibility requirements.”

Lets make it simple:

You fly the approach a CAT I ILS where a NOTAM is in force increasing the min viz to 4000 (1200m), as was the case recently at a previous carriers destination. You reach the MDA and can see the approach lights and the decision bar and several rows beyond that. But you cannot see the runway threshold lights.

Do you land?

[AerocatS2A]

Lets make it simple:

You fly the approach a CAT I ILS where a NOTAM is in force increasing the min viz to 4000 (1200m), as was the case recently at a previous carriers destination. You reach the MDA and can see the approach lights and the decision bar and several rows beyond that. But you cannot see the runway threshold lights.

Do you land?

Is there a corresponding raise in the MDA as well? Typically a change in required vis goes hand in hand with a change in MDA or DA, in which case the amount of runway lighting you can see will probably be the same.

[Radu Poenaru]

You reach the MDA and can see the approach lights and the decision bar and several rows beyond that. But you cannot see the runway threshold lights.

Do you land?

Of course I will; but I live in EASA-land where all I need is visual ref with one of about 11 items. :p

Is there a visibility requirement for CAT I approaches? Yes. And that visibility is measured by very smart people on the ground and then reported to the pilots.

Is the pilot expected to measure/assess such visibility once he is at MDH/DA? No. He has no idea how to do it, we don't trust him to do it accurately, and he doesn't have the time:need to focus on the landing.

Is the pilot entitled to a go-around after assessing he does not have the required visibility if the runway is in sight? Well, you should always feel free for a go-around whenever necessary, so I'll answer yes. Especially if you feel you have a poor visual contact. Depending on airline you might have to explain it, though... and the chief pilot might not buy it.

[A Squared]

Is there a visibility requirement for CAT I approaches? Yes. And that visibility is measured by very smart people on the ground and then reported to the pilots.

That is not correct in the land of the FAA. The specific legal requirement is for "flight visibility" and flight visibility cannot, by definition, be measured by people on the ground or by RVR sensors. Yes, it is explicitly defined to be distinct from reported visibility, and the distinction is not trivial.

That distinction is crucial to the ability to legally land when the reported visibility is below the specified minimum.

[wiggy]

Sorry, I'm easily confused, but before I start I'd point out that I'm an EASA-lander so I'm used to doing things the way the likes of Radu described.

That distinction is crucial to the ability to legally land when the reported visibility is below the specified minimum.

So are you saying you would continue an approach beyond the Approach ban point/1000' aal/FAF as appropriate, despite the ATC reported visibility being less than minima, in order to do your own assessment of "in flight visibility" at DA/MDA?

[A Squared]

So are you saying you would continue an approach beyond the Approach ban point/1000' aal/FAF as appropriate, despite the ATC reported visibility being less than minima, in order to do your own assessment of "in flight visibility" at DA/MDA?

No, I wouldn't. That would not be legal under Part 121 regulations. (It would, however be legal if I were not operating under Part 121 or 135) . However, if I was advised that the reported visibility had decreased below minimums *after* I had progressed the FAF, I could legally continue the approach and land if flight visibility was above the minimums.

In FAA world, reported visibility is controlling for beginning the approach (Part 135) or continuing the approach beyond the FAF (Part 121) but flight visibility is controlling for descending below MDA/DA and landing.


If you find this confusing, that's because it is. But keep in mind that there are certain situations where reported visibility may be very different than flight visibility. One example might be a situation there is a localized fog bank in the vicinity of the observers position, but other parts of the airport are in the clear. Another example is blowing snow. Blowing snow tends to affect RVR systems very differently than fog and precipitation. I have on more than one occasion, held at the outer marker in clear conditions with the entire runway in sight, but unable to go past the FAF because the measured RVR was below the published minimum due to blowing snow. Those are extreme examples, but the point is the FAA's regulations are written to allow for the fact that flight visibility is not the same as reported visibility from a ground observer.

[wiggy]

Ah, OK, thanks for the clarification and the background info..

[Radu Poenaru]

Ha! Thanks for the clarification. One simple word changed & it makes a lot of difference. I think I get it now...

I'm still left wondering how is the FAA expecting to enforce this? "Yes, your honor, the RVR was only reporting 100 meters, but I had a flight visibility of 8 miles"

[peacekeeper]

To quote Ernest K. Gann

Rules books are paper - They will not cushion a sudden meeting of stone and metal

Surely a certain amount of pragmatism has to be applied. Regardless of the rules, anything other than an instant decision whether a safe landing can be made is dangerous. If you are interpreting the rules so much that you are adding complexity at a critical time, the rules have failed. The decision to go around should have been built on the way to minima, when you get there it is a simple Land or Go around. If it's marginal and you don't think you like it, throw it away, don't wait until 100ft regardless of the rule book. If there is a CAT 2 or 3 available, try that on the next one, if not, it's not your day, divert.

I'm also an EASA operator but I think common sense is universal.

Safe flying

PK

[A Squared]

Ha! Thanks for the clarification. One simple word changed & it makes a lot of difference. I think I get it now...

I'm still left wondering how is the FAA expecting to enforce this? "Yes, your honor, the RVR was only reporting 100 meters, but I had a flight visibility of 8 miles"

True, it would be difficult to enforce, but it doesn't seem any more or less difficult to enforce than having the required visual references. ( "Yes your honor, I had XXXX in sight at DA" )

Really, it seems like your system makes more sense, if I understand it correctly. ie: Start the approach based on reported visibility, decide to continue below DA based on visual reverences only. Having the decision to descend below DA be based on visual references *and* flight visibility, which may be difficult to determine, and may differ from the visual references introduces a grey area, which leads to questions like the OP. As Peacekeeper pointed out, it adds complexity at a critical time.