Air Canada suing Airbus re: Halifax crash landing

[Canoehead]

Sorry Vsplat, but can you explain how you Temp Comp vertical speed?

 

[Kip Powick]

19 minutes ago, Rich Pulman said:

I remember being a young lad on Squadron in the early '90s and commiserating to my more "mature" Squadron-mates

To a point I will agree except I heard the same thing........ but it was in the early 60's

 DND was a different arena. I was on 4 AIB's and none had to do with any instrument phase of flight...three were the result of being "stupid"  and attempting  to do something with an aircraft that was not possible.....and one was flying while on drugs.

Here ends my part of being guilty.... with respect to thread drift.

[Boney]

This is all interesting. What if, and I believe this to be the case, they arrived at the DA correctly and had the runway in sight, thus was now able to continue to land. The wx, especially the wind, at the time of the start of the approach was acceptable, but at the time of the incident, there was a report of the wind gusting up to 50+ knots. 

Is it possible that they had a sudden increase in wind followed by a sudden drop which caused a drop in airspeed that the onboard computers dropped the nose to prevent a stall? I ask as I've heard that the airbus computers tend to correct attitudes, without consent from the pilots, while in "normal law" to keep pilots honest, thus catching them off guard.

I stand corrected as I'm not an Airbus driver.

Maybe this could be the reason for the lawsuit. 

[Zan Vetter]

FPA on the airbus is an easily misunderstood feature, speaking for myself only.

To wit, if you compensate your FAF-crossing altitude for cold temp by some nominal amount (300 feet, say), you've only just placed your flight path back on the normal profile. Yet, we also then add compensation (increase) to the FPA (-3.3 vs -3.0 say), directing the aircraft to fly a steeper approach angle, as if the aircraft were going to cross the FAF higher than the normal alt, thus needing to descend steeper to arrive at the MDA+50 at the MAP.

Explanations as to why this is, to me, have always fallen short; mostly I get some kind of reference to FPA being a path "in space", calculated by the FMS, therefore this-and-that. Which has never made complete sense to me. If you cross the FAF at the right height AGL, which is what your compensated FAF-crossing altitude is for, I've always stumbled when attempting to understand why FPA needs to increase. It is after all a selected approach, not a managed approach, which has always meant to me that the crew inputs are primary, and there is no calculated- or pseudo-path angle in play. Anyhow, I follow the procedures as published, use the charts as directed and trained, as I'm sure this crew did as well. It's always worked out, but I've only done it in weather significantly better than that of this accident.

Bottom line, how the airbus calculates and flies its flight path angle vis a vis the FPA angle selected by the flight crew is in no way transparent or clear. So the crew would not have a clear signal if it was in error somehow, until they got to the MAP. So without commenting on the possible outcome of the lawsuit, it doesn't surprise me at all that it exists.

[blues deville]

1 hour ago, Boney said:

This is all interesting. What if, and I believe this to be the case, they arrived at the DA correctly and had the runway in sight, thus was now able to continue to land. The wx, especially the wind, at the time of the start of the approach was acceptable, but at the time of the incident, there was a report of the wind gusting up to 50+ knots. 

I think the extreme wind conditions played a critical part in this accident. Just when you're about to transistion to (hopefully) visual, the aircraft would be crabbing into the wind while maintaining the lateral segment of the approach. The runway/lights would have been to the right of the nose. If the Captain was PF it might have been hidden behind the center window post. A few extra seconds at ground speed mini searching for it and now you're lower than desired. I get shakey just thinking about. I bet those boys wish they'd just parked that Airbus in Moncton. 

[Boney]

Agreed that the wind was the major factor. Hope the report comes out sooner rather than later so that we can learn from this incident. 

Cheers. 

[Boney]

Good to know. Like I said, I don't know the airbus. 

Cheers. 

[anonymous]

The reason one corrects the FPA is because FPA uses baro-inertial vertical speed in calculations to create FPA. The baro part is referenced to a standard atmosphere and therefore has an error in colder-than-normal operations.

Sometimes it does seem like one is using a micrometer to measure and an axe to cut when it comes to flying  NPAs  .. some companies' SOPs  have turned a NDB into a Cat III NDB.

 

[DEFCON]

It's been awhile, but it seems the arguments being made here regarding the CDA are not considering the role of gs from the FAP fix to GA in the approach equation. IOW's, if you apply the wrong gs, the calculated vs will bring you to the MDA / decision point either too early, or too late.

No matter how you cut it, non-precision approaches are still non-precision and being so invite all forms of opportunity for handling errors to occur.  

 

[blues deville]

1 hour ago, DEFCON said:

 

No matter how you cut it, non-precision approaches are still non-precision and being so invite all forms of opportunity for handling errors to occur.  

 

 I think you've nailed it Defcon. I also think that no matter how much NPA training  pilots receive, these are probably flown the least. Add in crappy weather and voila. 

Back to the initial thread topic, I still find it interesting that AC's lawyers have filed this suit against Airbus. AA had a bad crash in MBJ awhile ago writing off a 737NG but there was no legal action taken with Boeing. I believe these lawyers have some knowledge of the TSB report contents and are just protecting the mothership which would be normal procedure in this situation. 

Over two years for a TSB report? This isn't   Malaysia. What's the deal?

[Guest]

2 hours ago, blues deville said:

 I think you've nailed it Defcon. I also think that no matter how much NPA training  pilots receive, these are probably flown the least. Add in crappy weather and voila. 

Back to the initial thread topic, I still find it interesting that AC's lawyers have filed this suit against Airbus. AA had a bad crash in MBJ awhile ago writing off a 737NG but there was no legal action taken with Boeing. I believe these lawyers have some knowledge of the TSB report contents and are just protecting the mothership which would be normal procedure in this situation. 

Over two years for a TSB report? This isn't   Malaysia. What's the deal?

Lawyers (those vetting the report before issuance) like to have every "i "dotted and every "t" crossed, before putting on their belts and ensure that they have added suspenders to make absolutely certain their pants don't fall down. At least so I found from the many Lawyers that I worked with during my "Regulatory Days".  

[blues deville]

3 minutes ago, Malcolm said:Lawyers (those vetting the report before issuance) like to have every "i "dotted and every "t" crossed, before putting on their belts and ensure that they have added suspenders to make absolutely certain their pants don't fall down. At least so I found from the many Lawyers that I worked with during my "Regulatory Days".  

You're probably right. Although I find some of these people today are "shoot first and ask questions later" types. And don't ever let the facts interfere.

Bottom line here is AC will come out of this, move on and perhaps we will all learn something. 

[Guest]

9 minutes ago, blues deville said:

You're probably right. Although I find some of these people today are "shoot first and ask questions later" types. And don't ever let the facts interfere.

Bottom line here is AC will come out of this, move on and perhaps we will all learn something. 

And I also hope the crew will also "come out of this, move on and perhaps".   Cheers

[blues deville]

I guess that takes care of that then....

 

[Kip Powick]

All the input is very interesting and the advent of the technology with many explanations tends to cloud or muddy, if you like, what actually happened at YHZ. 

I have spent too many hours researching the latest trend in flying NPA/ FPA approaches, and the written expertise which suggests that aircrew get away from "step-down" NPA and it all seems to boil down to a few things....

The ideal situation, with the latest technology, is to have a stabilized approach all the way in from the FAF and using the FPA to meet the MDA, and ideally, very close to the MAP, and at that point  be in suitable weather conditions and carry out a visual landing.

Let us assume that happened...then why did the aircraft touchdown short of the runway ?? 

Only two reasons come to mind......reliance on the FPA in gusty turbulent weather and more instrument flying than visual flying after the  MDA/MAP or.............. the lack of good visual acuity after the  MDA/MAP  during the "landing" phase

Based on what I have read the temperature, at best, would change the MDA by about 20- 25 feet which is really negligible in the approach phase of the flight.

Just an opinion....the advent of the technology is certainly easing the work load of the pilots but in moving forward with the cockpit magic comes the drawback of glossing over basic flying skills as well as complete and total situational awareness when in close proximity to the terra-firma.

 

PS.... I see nothing wrong with reaching MDA early and having to maintain MDA for a short period of time until MAP or landing. It certainly "smooths" out a flight if one uses the FPA and all the numbers come together  and one only has to call for landing flap, or not, and put the "rubber on the road" but before the aircraft had all the electrons etc.......basic flying skills and using all the numbers on the approach chart got us to the runway.

 

[blues deville]

The MDA on LOC05 is 820' (357') so temp correction (-8c?) would be closer to 40' plus another 50' for the NPA. 

[rudder]

The change that must (and hopefully will) come about is a regulatory requirement that the approach ban required visibility for a non-precision approach will be the charted visibility. This is the global standard. It is just not the current Canadian standard.

This appears to be just one of several recent incidents related to actual visibility on non-precision approaches that was at or near visibility that would have been challenging even on a precision approach.

[Kip Powick]

56 minutes ago, blues deville said:

The MDA on LOC05 is 820' (357') so temp correction (-8c?) would be closer to 40' plus another 50' for the NP

Yes, your chart is more up to date than mine..I show TDZE as 463 and the MDA as 740 for a LOC/DME approach

[blues deville]

I wasn't aware on the night of this event the VASI's for RW05 were buried in snow and unusable. Crap. Monday morning QB's would probably say "take a knee" on this one. 

[Moon The Loon]

One would think the crew had flown into Halifax many, many times. One assumes that. (Yeah, I know...)

Could they have possibly misread the airport lighting and believed the approach lights were actually touchdown zone lighting, which of course does not exist on this runway? I never really thought of it until now, but it could explain why they hit the ground so far outside the airport boundary...

Time will tell. Hopefully these WAG's will get put to rest shortly.

[Don Hudson]

Van Zetter, re:

Quote

. . . we also then add compensation (increase) to the FPA (-3.3 vs -3.0 say), directing the aircraft to fly a steeper approach angle, as if the aircraft were going to cross the FAF higher than the normal alt, thus needing to descend steeper to arrive at the MDA+50 at the MAP.

Explanations as to why this is, to me, have always fallen short; mostly I get some kind of reference to FPA being a path "in space", calculated by the FMS, therefore this-and-that. Which has never made complete sense to me. If you cross the FAF at the right height AGL, which is what your compensated FAF-crossing altitude is for, I've always stumbled when attempting to understand why FPA needs to increase.

Baro altitude is corrected at the FAF etc, but the air is cold all the way down to the runway. If the airplane doesn't have GPS or temperature-compensating baro-VNAV, then a selected FPA must be steeper because colder-than-standard air reduces the pressure gradient, reducing the change in baro-altitude reading, and the FPA profile thereby ends up being a bit too shallow and a bit high approaching the threshold.

If the airplane has the necessary equipment, (position sensing, etc), the calculation is internally correct, and can be flown as a Managed approach, whether flown manually (following the flight directors!), or using auto flight.

"Selected" has to be corrected because, as Vsplat has stated a few times, it isn't "anchored".

[Kip Powick]

Just my opinion from "out in the pasture".....

I really seem to be missing something here...Lots of discussion about FPA and temperature and perhaps I am really out to lunch on this whole discussion but in my mind it doesn't matter what happens to the FPA in varying temperatures.

My point is, and always will be, that during any type of NPA, one does not go below MDA until one has visual conditions suitable for a landing.

If flying a NPA using the FPA venture  and one arrives at MDA, ,does one continue flying the FPA???? Why would anyone ever do that? ......unless they felt that "instrument flying" below MDA , using FDA, is going to result in a successful approach in, shall we say, marginal/questionable visual conditions and should that be the justification for doing so .................well, in my mind...........  that is not acceptable, and should not be condoned.

Perhaps technology has bypassed this guy who hung up his spurs decades ago, but it seems to me that the basics of flying a NPA have been overshadowed by the attempt to blend instrument flying with visual flying and that is just NOT the way to terminate an approach and landing.

[Seeker]

13 minutes ago, MD2 said:

It has already been mentioned that altimetry error has been ruled out (not sure if it has or not, but in any case), and the discussions are under the presumption that the aircraft descended below the MDA, however, is a condition possible under which the aircraft is put at, near, or below the terrain while still at or above the MDA with an incorrect FPA? That may be the direction this is going, just thinking out loud...

 

 

Think about it.  Failing to correct the FAF crossing altitude for cold temperature would lead to being lower than expected at the FAF and the possibility of a CFIT event.  Failing to correct the MDA for cold temperature would lead to being lower than expected at MDA and the possibility of CFIT but an error made to FPA can't, by itself, expose you to the danger of CFIT.  The crew could get to MDA too soon or too late, either of which might make a landing impossible but the risk is simply that the aircraft is in the wrong position to land not that the FPA will take the crew into terrain.

At the most basic level, the procedures are straight forward; correct the FAF for temperature, fly an FPA to a temperature corrected MDA, if you're stabilized at MDA and in a position to land - land, if you're not stabilized or not in a position to land - go-around.  The only threat from a bad FPA should be an unsuccessful approach.  There is, of course, the possibility that a crew might get to MDA too soon and try to drag the aircraft to the runway or loo late and dive at the runway.  This is really a stable approach issue.

[DEFCON]

I think Kip has been on the right track all along, 'depending' on automation to provide flight trajectory guidance during the 'visual' portion of a np approach is potentially dangerous.

It will be unusual, but without the TSB's final report in hand we'll probably be getting the crash details from AC's Statement of Claim.

Anyone remember the days of fun when we might be called upon to fly something like an ndb / dme arc approach with fixed card adfs to intercept a bc loc with reversed course indicators and finishing with several step downs while heading to and after passing the FAF at night in crappy weather and winds?

It's only my opinion, but I think a pilot will only become a competent user of the available modern technologies if he first develops an appreciation for aircraft handling, which can only be learned through 'hands on' experience. When you fly full procedure np approaches by hand with primitive equipment in challenging circumstances one learns to evaluate and 'mentally' process all the information available in a fast paced real 3D environment, but when those important first steps are missed and a cadet climbs directly into the right seat of an airliner, it's easy to appreciate just how quickly things can unravel when he's challenged by simple automation failures.

 

 

  

[Homerun]

Kip/Defcon, we don't follow/fly the FPA below MDA.  It gets us to the MDA and that's it.  It is visual flying only from that point on....or a go-around if runway environment not in sight.