Halifax crash report coming Thursday

[pdw]

.. intrapolation may not be accurate enough to determine actual conditions at the time over the course of an accident.

I think i know what you mean here but just to be sure ... it's actually interpolation and extrapolation. I can illustrate point-of-view on this a bit more accurately over the next few days on this post (and hopefully other discussion isn't interrupting for a minor/potential variable we're talking about).

EDIT (Thurs Jun8):
The day of this accident flight (late Saturday) had noticed a LO image South of Nova Scotia on ADDS.

[Rockie]

While a lot of airline safety today is thanks to unions goldeneagle, it isn't a union driving this. Nice try though.

I believe Rockie is correct. It is a business decision by management to level the economic playing field with their competition that now has a competitive advantage because of the different safety record on the issue.

The quest for rule changes has absolutely nothing to do with interest in safety. Otherwise the case to make regulatory changes and internal procedures would have started long ago before there was an accident.

I wonder where thare are good examples of measurable differences on what airline gets to do an approach versus who doesn't under this new proposal? Just a guess using YTZ as an example. Maybe AC can scoop up some business pax due to their Low Vis Approach advantage in YYZ compared to increased cancellations and diversions from the competition(and their excellent safety record) while at the same time possibly eliminating a rerciprocal disadvantage at a CAT I airport like YOW. Advantageous for AC if it were to be true. And a situation that has no doubt hurt AC for years after their tryng to eliminate YTZ.

Any idea how other airlines like Porter might just happen to be affected Rockie, or should I avoid the subject?

To answer that I'd have to know what kind of approaches Porter does and the historical meteorological information on the island. But given their proximity to the city do you think their business plan hinges on the ability to use 1/2 the charted visibility on instrument approaches?

As this is a safety issue you also seem to be implying that only companies who can afford safety should be required to have it.

[pelmet]

I believe Rockie is correct. It is a business decision by management to level the economic playing field with their competition that now has a competitive advantage because of the different safety record on the issue.

The quest for rule changes has absolutely nothing to do with interest in safety. Otherwise the case to make regulatory changes and internal procedures would have started long ago before there was an accident.

I wonder where thare are good examples of measurable differences on what airline gets to do an approach versus who doesn't under this new proposal? Just a guess using YTZ as an example. Maybe AC can scoop up some business pax due to their Low Vis Approach advantage in YYZ compared to increased cancellations and diversions from the competition(and their excellent safety record) while at the same time possibly eliminating a rerciprocal disadvantage at a CAT I airport like YOW. Advantageous for AC if it were to be true. And a situation that has no doubt hurt AC for years after their tryng to eliminate YTZ.

Any idea how other airlines like Porter might just happen to be affected Rockie, or should I avoid the subject?

To answer that I'd have to know what kind of approaches Porter does and the historical meteorological information on the island. But given their proximity to the city do you think their business plan hinges on the ability to use 1/2 the charted visibility on instrument approaches?

Anybody else know if the self-regulating rules that AC now uses and which seems to be desired by some for all carriers would create a disadvantage to operators at YTZ?

[AuxBatOn]

.. intrapolation may not be accurate enough to determine actual conditions at the time over the course of an accident.

I think i know what you mean here but just to be sure ... it's actually interpolation and extrapolation. I can illustrate point-of-view on this a bit more accurately over the next few days on this post (and hopefully other discussion isn't interrupting for a minor/potential variable we're talking about).

If you are estimating at a time between two known data points, it is interpolation. Given the continuous nature of METARs at YHZ, it would ve difficult, in the context we are discussing, to extrapolate (unless you are estimating the weather in yhe future).

[pdw]

(unless you are estimating the weather in yhe future).

METARs a ways away from the action can interpolate via isobars/ speed / direction BACKwards-in-time for an accident's time/alt/location elsewhere. Wx info prior-to but a distance away can offer evidence where the storm's pattern was affecting and where had moved to from that point at the time the sequence event unfolded. TSB report lists all available wx-data from a single YHZ station well before and well after, which helps indicate where Halifax harbour was in relation to the passing pattern and also evidencing the extreme "54kts" mentioned.

[Meatservo]

Personally, and sorry for interrupting the narrative thread here, I think better visual approach-slope indicators need to be installed on instrument runways, and having visual contact with them should be requirement for deciding to continue below minimums, not just the lead-in or edge lights. That, plus the weird approach-slope guidance the crew had that doesn't take geographic location into account (apparently), makes me glad I wasn't there. I might have done the same thing. Feel free to abuse me for saying so. Without the PAPIs or VASIs, slope is difficult to ascertain visually at night. The "bird" instrument described in the report, which if I am reading correctly computes slope relative to the aircraft and not relative to the touchdown point, does not seem up to the task.

[Rockie]

Personally, and sorry for interrupting the narrative thread here, I think better visual approach-slope indicators need to be installed on instrument runways, and having visual contact with them should be requirement for deciding to continue below minimums, not just the lead-in or edge lights. That, plus the weird approach-slope guidance the crew had that doesn't take geographic location into account (apparently), makes me glad I wasn't there. I might have done the same thing. Feel free to abuse me for saying so. Without the PAPIs or VASIs, slope is difficult to ascertain visually at night. The "bird" instrument described in the report, which if I am reading correctly computes slope relative to the aircraft and not relative to the touchdown point, does not seem up to the task.

Your understanding of flight path angle (FPA) is correct, but you are incorrect in saying it is not up to the task. It is a stable, safe way to conduct non-precision approaches, provided non-precision visibility limits commensurate with the available lighting exists. Where Canada goes wrong is allowing precision approach visibility limits to be used.

It's a recipe for this kind of accident.

[Meatservo]

But that's what I meant: it wasn't up to THIS task.

[Rockie]

I understand and you're absolutely right. What I'm saying is that since TC cannot conjure an approach to match the visibility, they must properly regulate the visibility required for the approach.

[goldeneagle]

I understand and you're absolutely right. What I'm saying is that since TC cannot conjure an approach to match the visibility, they must properly regulate the visibility required for the approach.

That would be the case if there was an expectation folks would continue an approach with insufficient visual reference 'just because the vis report doesn't ban the approach' which is indicative of a 'must get in' attitude.

Your insistence that regulations must be changed because it's not appropriate for a big heavy jet that is blindly adhering to the constant descent 'must keep descending' mantra does not acknowledge that not all airplanes are created equal, and it's a whole different world in a well powered nimble light twin. If the big jets need higher limits, so be it, but suggesting it applies to everybody is kinda like saying we need a regulation saying nobody can go into a 500 foot grass strip which is perfectly useable for a light super cub, but, rather unsafe with your big jet.

A completely different tack, that would satisfy your desired objective, leave regulations alone, but increase the plate numbers for the cat C and D big heavy fast stuff that seems to be incapable of levelling off at MDA if they are a bit short. Double those numbers and you achieve your objectives for big jets, and leave those of us that can doddle along low and slow at MDA with the option to do exactly that.

[Rockie]

A completely different tack, that would satisfy your desired objective, leave regulations alone, but increase the plate numbers for the cat C and D big heavy fast stuff that seems to be incapable of levelling off at MDA if they are a bit short.

Not a bad idea, but there's nothing wrong with the plate numbers except that they don't consider the approach lighting available. I think more appropriately the charted minimums should apply without reduction to any aircraft utilizing SCDA's. That would be a suitable compromise in my opinion, although I still don't get why Canada feels using lower than published minimums is safe when the rest of the world does not. We are the outlier and we need to question why.

Remember when they used to print the visual descent point (VDP) on non-precision approach plates? The idea was you would descend down and level off at MDA, then drive in safe and level until the missed approach point watching for visual references to the runway gradually appear...or not. As you passed the VDP you knew your chances of being able to land safely rapidly diminished, and descending from MDA required an actual decision and positive action on your part based on your assessment of position.

In a precision approach you already know you are headed laterally and vertically toward the correct touchdown spot on the runway (that's why it's called precision), and all you really need to see is essentially any of the required visual references to continue. Completely safe unless you subsequently lost sight and were forced into a go-around.

With SCDA we are forcing the same decision making criteria on the crew without any of the safeguards a precision approach offers, and without any of the advantages a dive and drive NPA provides.

I would definitely be in favour of eliminating the approach ban for SCDA's only if that were an option.

[Eric Janson]

A completely different tack, that would satisfy your desired objective, leave regulations alone, but increase the plate numbers for the cat C and D big heavy fast stuff that seems to be incapable of levelling off at MDA if they are a bit short.

This is already the case - at my Airline we are not allowed to fly approaches below charted visibility requirements. These visibility requirements ensure that adequate visual references can be seen at MDA/DA/DH to allow for a safe continuation and landing.

With SCDA we are forcing the same decision making criteria on the crew without any of the safeguards a precision approach offers, and without any of the advantages a dive and drive NPA provides.

I don't agree - SCDA is the safest way to fly an NPA. Dive and Drive can lead to an unstabilized approach close to the ground.

I've worked for companies where we were allowed to level off at MDA because the NPA's at that time did not have a CDA profile published. This is extremely dangerous imho and has resulted in plenty of CFIT accidents over the years.

On an SCDA you have altitude vs. DME to allow monitoring of the vertical profile. This should put you in a position from which you can land with only minor corrections. The LOC Rwy 05 approach has 7 points at which this can be done after passing D9.5 IHZ.

There is nothing difficult about flying an NPA using LOC/FPA modes imho.

The only thing that I would have preferred to see on this approach is a co-located DME on the localizer IGX that would read zero at the threshold.

Flying an NPA in precision approach weather is asking for problems as is choosing to ignore the manufacturers SOPs.

I can see an issue flying NPA if you don't do them regularly. I imagine it's perfectly possible to never fly an NPA outside the Simulator.

[Rockie]

You misunderstand my meaning Eric. The advantage I'm referring to using a dive and drive method is the ability to watch the required visual references develop as you approach the runway environment level at MDA within your bubble of visibility. This allows you time to make the assessment.

While the SCDA is unquestionably safer from a CFIT point of view it does not permit you the same time to watch the visual references develop, and when you reach MDA you have to make a decision without knowing precisely where you are. Which is why the visibility has to be good enough, and the required visual references have to be increased to actually permit you to assess your position instantly.

I do not advocate dive and drive in transport aircraft. I'm merely pointing out the "handicap" SCDA's impose on a crew without any of the guarantees a precision approach offers, nor the advantage a dive and drive gives in time to assess.

[av8ts]

If AC had invested in GPS aboard this aircraft like most other Canadian companies the crew would not have been "handicapped " doing a nonprecision approach. This was probably in the original accident report but removed after pressure from AC

[Rockie]

If AC had invested in GPS aboard this aircraft like most other Canadian companies the crew would not have been "handicapped " doing a nonprecision approach. This was probably in the original accident report but removed after pressure from AC

Not necessarily true. The LOC approach uses DME as the descent point making it just as accurate as GPS. it would however have provided vertical guidance within the temperature range of the LNAV/VNAV which may have made the difference. In this case the AP would disconnect automatically at MDA -50, so who knows what effect that may have had given the visibility.

You won't find anybody arguing against equipping with GPS though except maybe the accountants. WAAS would be better.

You're also speculating that the TSB would editorialize on the equipment onboard the aircraft, when they had the legal equipment to do a legal approach to legal weather. A bit of a reach.

[Eric Janson]

You misunderstand my meaning Eric. The advantage I'm referring to using a dive and drive method is the ability to watch the required visual references develop as you approach the runway environment level at MDA within your bubble of visibility. This allows you time to make the assessment.

While the SCDA is unquestionably safer from a CFIT point of view it does not permit you the same time to watch the visual references develop, and when you reach MDA you have to make a decision without knowing precisely where you are. Which is why the visibility has to be good enough, and the required visual references have to be increased to actually permit you to assess your position instantly.

I do not advocate dive and drive in transport aircraft. I'm merely pointing out the "handicap" SCDA's impose on a crew without any of the guarantees a precision approach offers, nor the advantage a dive and drive gives in time to assess.

Don't forget the additional 'handicap' of trying to fly VFR in IMC whilst trying to find the runway on a dive and drive approach. That's killed a lot of people.

SCDA will get you to a point from which you can easily continue to landing with minimal changes to your vertical profile. You'll see the same 'picture' every time.

Not working out? - Go-around.

It's very simple - I'm a big proponent of keeping things simple.

[Rockie]

Yes, once again I agree with you. The problem with SCDA's is that they are not precise as Halifax amply demonstrated. It is not good enough to just see "something" as permitted in the required visual references, and is sufficient with the guarantees present in a precision approach. You have to see that you are in the right place at the right altitude and with the right flight path trajectory. That requires significantly more than precision approach visibilities.

[pdw]

This is the first time these two pilots had flown together.

IMO to ID "something" in the min-vis WX at 05-HZ with the above SCDA-description, and being "first time", ... ie they'd have had to have done the approach before in that soup to recognize anything and to anticipate it correctly.

[Canoehead]

This is the first time these two pilots had flown together.

IMO to ID "something" in the min-vis WX at 05-HZ with the above SCDA-description, and being "first time", ... ie they'd have had to have done the approach before in that soup to recognize anything and to anticipate it correctly.

It was the first time they'd flown together. It happens every day hundreds of times. It's why we have standard calls and SOP's.
That has nothing to do with what they saw/identified/didn't see.

[pdw]

Just that it was mentioned (about the first time pairing ... CRM) ... then the "staff change in the tower" during approach, also in there. It's challenging to understand how these variables all fit ...