WestJet almost puts one in the drink

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pelmet
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Re: WestJet almost puts one in the drink

Post by pelmet »

Haven't read it all but....

"On final approach, the aircraft was stabilized on a 3° angle of descent and configured for landing. Approximately 0.5 nm before the MAP, the flight crew decided that, given that they had the shoreline in sight and expected to see the runway shortly afterward, they would continue the approach visually. At that point, the aircraft was descending at approximately 820 feet per minute (fpm) and at 159 knots indicated airspeed, with an N1 of approximately 62%.
The pilot flying (PF) then disconnected the autopilot as per WestJet's approach procedures for landing at TNCM. Shortly afterward, the PF reduced the pitch from 0.5° nose up to 1.2° nose down, which initiated an increase in airspeed. In response to the airspeed increase, the autothrottle command reduced the engine thrust from 62% to 52% N1 to maintain the 160-knot speed previously set in the flight management computer (FMC). Following the reduction in thrust, the aircraft began to deviate below the 3° angle of descent, at a descent rate of between 1000 and 1150 fpm. Shortly after, the PF cycled the flight directors and started to manually manipulate the thrust as per WestJet's approach procedures for landing at TNCM. The reduction in the pitch attitude led to an increase in airspeed, which resulted in a reduction in engine thrust and a higher rate of descent than that required by the 3° angle of descent."


If you are on a three degree path to the runway, you obviously want to make sure you remain so after disconnecting the autopilot. Depending on how the FMC is configured, on some Boeings, the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars. If familiar with the FMC waypoints, you can tell this by looking at the waypoints in the FMC. Then you can just follow command bars while having your marginal but legal required visual references which in reality, provide little depth perception and quite possibly, misleading cues.

If for some reason, you won't be using the flight director cues from the FMC generated path, you might consider using the VS function to give you similar flight director guidance or the more accurate Flight Path Angle if it is installed. A simple push of the appropriate button at the desired, stable descent rate give a continuation of what you already have. But even without this stuff, you can do just like in the good old days......if you know you are on the proper descent angle, just maintain the same rate of descent which can be maintained by keeping the same pitch once the autopilot has been disconnected. Just because the autopilot is off doesn't mean you can't continue to look inside and fly the aircraft on instruments while the other guy is monitoring both inside and outside with the required visual references until clarity with its proper depth perception slowly or quickly comes into view.

There can be a tendency to inadvertently push or pull on the control column once visual if the PF changes most or all focus to the outside environment, especially in marginal conditions. Good discipline can prevent this, perhaps by making a mental note about it at an earlier time to prevent this situation. Sometime it is just best to stay on the instruments for a little while longer.
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Last edited by pelmet on Mon Jun 11, 2018 10:42 am, edited 1 time in total.
Noo
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Re: WestJet almost puts one in the drink

Post by Noo »

"the crew cycled the flight directors, in accordance with WestJet's approach procedures for landing at TNCM"

Does this mean turn the FD's off then on again? Is this a common practice for the 737? Why would they do this?
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ahramin
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Re: WestJet almost puts one in the drink

Post by ahramin »

You turn the FDs off so that you aren't following a made up glide path below minimums. They are cycled so that they are available for the go around.
the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars.
This is exactly why accidents and incidents like this will continue to happen. Continuing past minimums without enough visibility to land visually may work out most of the time, but most of the time isn't good enough.
Then you can just follow command bars while having your marginal but legal required visual references
is the perfect recipe for an AC624 or worse.

Go arounds are your friend. It's easy, you've practiced it in the sim, your day will be fine. If you are 300' above minimums and not quite sure if you can see enough to continue to land, continue to minimums. If you are AT minimums and not quite sure if you can see enough to continue to land, Go Around Flaps.
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Noo
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Re: WestJet almost puts one in the drink

Post by Noo »

So you turn the FD's off and then on again right way? What are they displaying when you turn them on again?
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Re: WestJet almost puts one in the drink

Post by Go Guns »

That particular approach, the missed approach point is 2 miles shy of the runway, the next waypoint after the MAP is on the missed approach procedure, nowhere near the airport. So if you followed the FMC information via the flight directors, it would not take you to the airport. So, at the MAP with the required visual reference, autopilot disengaged, cycle the flight directors. This will kick the autothrottle into ARM mode, and blank the FMA and the flight directors. Should you press TOGA, the flight directors will come alive with LNAV and TOGA, autothrottle will be in GA.
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shamrock104
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Re: WestJet almost puts one in the drink

Post by shamrock104 »

It's a shame about their lack of transparency on this, maybe now with the initial report published they will make some sort of a statement but I don't believe they will.
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pelmet
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Re: WestJet almost puts one in the drink

Post by pelmet »

ahramin wrote: Tue Jun 05, 2018 9:24 am
the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars.
This is exactly why accidents and incidents like this will continue to happen. Continuing past minimums without enough visibility to land visually may work out most of the time, but most of the time isn't good enough.
Then you can just follow command bars while having your marginal but legal required visual references
is the perfect recipe for an AC624 or worse.

Go arounds are your friend. It's easy, you've practiced it in the sim, your day will be fine. If you are 300' above minimums and not quite sure if you can see enough to continue to land, continue to minimums. If you are AT minimums and not quite sure if you can see enough to continue to land, Go Around Flaps.
Almost every airline pilot has been in a situation like these guys were in. Half mile back from the MAP with some visibility. If they had just continued on their path to minimums as you said, then they could have made their decision. Instead, according to the report, they decided to "continue visually" at which point the pitch was decreased significantly and things went downhill from there. Perhaps they were trying to duck under a cloud base.

My recommendations are perfectly fine. It is not a recommendation to do this sort of thing to 50 feet on instruments, it is just not to go 100% visual right away. Continue with the stable approach with your required visual references but difficult depth perception(because you are over water) until things are clearer. It could apply on a clear black hole night as well.

Before we start writing exaggerated replies talking about this will lead to accidents, one need only look at figure 3 in the report. While I realize that it is only a simulation of the approach, it is a perfect example of having the required visual references in a murky condition with no depth perception. There is no reason to go around with this picture being presented to the pilots but good reason to continue with 80% or more of the PF's concentration being inside and continuing the approach on the path or continued normal rate of descent depending on the technology available.

It is difficult to know what exact picture was presented on that approach but I have read more of the report it seems to hint that the hotel was misidentified as the runway based on its shape and quite possibly in my opinion because it was the thing that was most visible in the murky view as compared to the actual runway.

If you are on an FMC generated(through GPS updating) typical descent path to a runway and in murky/night conditions and it appears that you have to make a significant change to the current path to align laterally or vertically with the runway, start wondering if you have misidentified the runway.
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Last edited by pelmet on Mon Jun 11, 2018 10:43 am, edited 1 time in total.
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Re: WestJet almost puts one in the drink

Post by Dry Guy »

The poster a few above you said the FMC would not take you to the airport. I guess there is no waypoint there? So following your FD's to continue the approach apparently would not work.
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Re: WestJet almost puts one in the drink

Post by pianokeys »

shamrock104 wrote: Tue Jun 05, 2018 1:20 pm It's a shame about their lack of transparency on this, maybe now with the initial report published they will make some sort of a statement but I don't believe they will.
YEAH DONT WORRY ITS ALL OKAY! NOTHING TO SEE HERE! NORMAL!
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Re: WestJet almost puts one in the drink

Post by confusedalot »

Dry Guy wrote: Wed Jun 06, 2018 7:20 pm The poster a few above you said the FMC would not take you to the airport. I guess there is no waypoint there? So following your FD's to continue the approach apparently would not work.
Too lazy to read the whole thread but I get the gist.

I confirm to anybody out there that the FMC, if properly set up, will get you to the threshold of the runway at the proper altitude and the proper position. It's been doing that since 1988 from my first experiences with the equipment and well before that, even before gps became popular. IRS, DME/DME, VOR/VOR, VOR/DME, and all of those sort of rnav combinations get you to your target.

Most pilots keep an eye on their magic even if they are visual. Yet, we as humans, do in fact get distracted. They fell into the trap, and that is not a condemnation or judgement. Shit happens as they say. Those two will never fall into that trap again.

Height judgement over water in reduced visibility is a bit tricky in my experience, but that's just me.
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Re: WestJet almost puts one in the drink

Post by C.W.E. »

Height judgement over water in reduced visibility is a bit tricky in my experience, but that's just me.
It is not just you, it can be very tricky.
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Re: WestJet almost puts one in the drink

Post by Dry Guy »

confusedalot wrote: Wed Jun 06, 2018 7:48 pm Too lazy to read the whole thread but I get the gist.

I confirm to anybody out there that the FMC, if properly set up, will get you to the threshold of the runway at the proper altitude and the proper position. It's been doing that since 1988 from my first experiences with the equipment and well before that, even before gps became popular. IRS, DME/DME, VOR/VOR, VOR/DME, and all of those sort of rnav combinations get you to your target.

Most pilots keep an eye on their magic even if they are visual. Yet, we as humans, do in fact get distracted. They fell into the trap, and that is not a condemnation or judgement. Shit happens as they say. Those two will never fall into that trap again.

Height judgement over water in reduced visibility is a bit tricky in my experience, but that's just me.
From what I've read above it sounds like Westjet's policy is to turn off the flight directors if continuing past the MAP. I'm not sure if that is only for this approach or for all approaches. The MAP for this approach was at 2 miles before the runway so they would just have raw data to go on from then which is easier to ignore than a flight director showing you way below your previous glidepath.
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pelmet
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Re: WestJet almost puts one in the drink

Post by pelmet »

Dry Guy wrote: Wed Jun 06, 2018 7:20 pm The poster a few above you said the FMC would not take you to the airport. I guess there is no waypoint there? So following your FD's to continue the approach apparently would not work.
If you re-read my post, you will see that I was very, very, very careful with my words. I made contingencies for various aircraft and technological set-ups as to what would be the best thing to do to remain on a proper path to the runway in conditions conducive to a visual segment becoming destabilized.

"Depending on how the FMC is configured, on some Boeings, the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars. If familiar with the FMC waypoints, you can tell this by looking at the waypoints in the FMC. Then you can just follow command bars while having your marginal but legal required visual references which in reality, provide little depth perception and quite possibly, misleading cues."

"If for some reason, you won't be using the flight director cues from the FMC generated path, you might consider using the VS function to give you similar flight director guidance or the more accurate Flight Path Angle if it is installed. A simple push of the appropriate button at the desired, stable descent rate give a continuation of what you already have. But even without this stuff, you can do just like in the good old days......if you know you are on the proper descent angle, just maintain the same rate of descent which can be maintain by maintaining the same pitch once the autopilot has been disconnected."

It is correct that in some cases, the FD's will not take you to the desired location. It is important to be aware of this. Many years ago, a Air France ran a 747 off the runway in Tahiti following an unstabilized approach after trying to follow command bars on an early software FMC which levelled the aircraft instead of continuing the descent.

https://www.google.com/search?q=air+fra ... SUBRvre6lM:
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Re: WestJet almost puts one in the drink

Post by DropTanks »

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Re: WestJet almost puts one in the drink

Post by CCR »

If the FD is not turned off, it commands the missed approach turn and climb.
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Re: WestJet almost puts one in the drink

Post by J31 »

CCR wrote: Thu Jun 07, 2018 6:30 am If the FD is not turned off, it commands the missed approach turn and climb.
FINALLY someone who understands the ST Maarten RNAV Rwy 10 approach and what the Boeing 737 Classic/NG/Max flight director does at MAPON. MAPON is the missed approach point 2 miles from the runway.

That is why it is a visual maneuver with no lateral or vertical electronic guidance the last 2 miles to the runway.
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Re: WestJet almost puts one in the drink

Post by Donald »

You guys are missing the point.

The PM did not call out the sink rate deviation. (Although the CVR is missing, so who really knows).

This is a failure of situational awareness, and failure of the PM. Just like SFO.
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pelmet
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Re: WestJet almost puts one in the drink

Post by pelmet »

J31 wrote: Thu Jun 07, 2018 3:24 pm
CCR wrote: Thu Jun 07, 2018 6:30 am If the FD is not turned off, it commands the missed approach turn and climb.
FINALLY someone who understands the ST Maarten RNAV Rwy 10 approach and what the Boeing 737 Classic/NG/Max flight director does at MAPON. MAPON is the missed approach point 2 miles from the runway.

That is why it is a visual maneuver with no lateral or vertical electronic guidance the last 2 miles to the runway.
Meaning one can fly the old fashioned way when the outside visual is as it was in figure 3 of the report. By maintaining pitch, power, and attitude while things become clearer although on some Boeing's, you can just select V/S and the command bars will display in such a way so as to maintain the rate of descent at the time of VS selection. FPA could do the same. All the while having the murky visual references but little depth perception.
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Re: WestJet almost puts one in the drink

Post by Eric Janson »

J31 wrote: Thu Jun 07, 2018 3:24 pm
CCR wrote: Thu Jun 07, 2018 6:30 am If the FD is not turned off, it commands the missed approach turn and climb.
FINALLY someone who understands the ST Maarten RNAV Rwy 10 approach and what the Boeing 737 Classic/NG/Max flight director does at MAPON. MAPON is the missed approach point 2 miles from the runway.

That is why it is a visual maneuver with no lateral or vertical electronic guidance the last 2 miles to the runway.
It seems to me that pushing HDG would be a smart move at MAPON - if I remember correctly the vertical mode will go to V/S. Leave the automatics until the aircraft is closer to the runway and then disconnect. Certainly lowers the workload and would have prevented what happened imho.
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Re: WestJet almost puts one in the drink

Post by photofly »

If there is little or no depth perception, how can you have to the “required visual reference necessary to continue the approach to land”?

For reference:

“required visual reference, in respect of an aircraft on an approach to a runway, means that portion of the approach area of the runway or those visual aids that, when viewed by the pilot of the aircraft, enable the pilot to make an assessment of the aircraft position and rate of change of position, in order to continue the approach and complete a landing; (référence visuelle requise)”

I guess what I’m asking is, if you need the command bars to continue the approach past the MAP (and can’t complete it safely without them) even if you have a visual reference, how are you meeting the intent of having a missed approach point?
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