WestJet almost puts one in the drink

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Cliff Jumper
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Re: WestJet almost puts one in the drink

#176 Post by Cliff Jumper » Sat Jun 16, 2018 6:56 pm

Eric Janson wrote:
Thu Jun 14, 2018 8:28 pm
Lower visibility results in the horizon being closer which makes the horizon line lower when looking outside. This creates the illusion of the aircraft pitch being high with an instinctive nose down input being the result. In this incident this is exactly what happened but the report doesn't discuss optical illusions.
Eric do you have any references to support this idea?
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digits_
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Re: WestJet almost puts one in the drink

#177 Post by digits_ » Sat Jun 16, 2018 7:23 pm

Cliff Jumper wrote:
Sat Jun 16, 2018 6:56 pm
Eric Janson wrote:
Thu Jun 14, 2018 8:28 pm
Lower visibility results in the horizon being closer which makes the horizon line lower when looking outside. This creates the illusion of the aircraft pitch being high with an instinctive nose down input being the result. In this incident this is exactly what happened but the report doesn't discuss optical illusions.
Eric do you have any references to support this idea?
You can easily check that yourself. For clarity, the horizon is defined as the apparent line that separates earth from sky (clouds).

If you are lined up on the runway, imagine the visibility is good and you can see all runway edge lights ahead of you. The horizon is above the edge of he runway. Now the visibility goes down, and you can only see half the runway edge lights. The horizon would now be at the points where you see those last runway edge lights. Now repeat this thought experiment and imagine the visibility goes down and you can only see 10 runway edge lights. Then 9, 8... etc. The horizon would always move down. If you were to draw a line on the windshield for every option during this experiment, you'd see the line move down.

Next, imagine you are in the airplane, 200 ft above the runway elevation, instead of on it. You could do the same experiment.

Now, imagine you are flying and you are used to having -depending on plane etc- a +2 degree attitude during final approach. You have that in your attitude indicator and you are nice and stable. You are now visual at minima and in your enthousiasm you ignore your attitude indicator for a moment and instinctively try to put your nose to a 2 degree attitude, looking outside at the horizon. We have established that lower visibility will give a lower horizon. You are now using a lower reference point to set your +2 degree, and will this have a lower attitude than you desire.
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Cliff Jumper
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Re: WestJet almost puts one in the drink

#178 Post by Cliff Jumper » Sun Jun 17, 2018 7:56 am

digits_ wrote:
Sat Jun 16, 2018 7:23 pm
You can easily check that yourself.
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?

There are quite a few (thousand) books on flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
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Cliff Jumper
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Re: WestJet almost puts one in the drink

#179 Post by Cliff Jumper » Sun Jun 17, 2018 7:56 am

Cliff Jumper wrote:
Sun Jun 17, 2018 7:56 am
digits_ wrote:
Sat Jun 16, 2018 7:23 pm
You can easily check that yourself.
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?

There are quite a few (thousand) books that describe flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
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Re: WestJet almost puts one in the drink

#180 Post by Cliff Jumper » Sun Jun 17, 2018 7:57 am

digits_ wrote:
Sat Jun 16, 2018 7:23 pm
You can easily check that yourself.
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?

There are quite a few (thousand) books that describe flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
[/quote]
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digits_
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Re: WestJet almost puts one in the drink

#181 Post by digits_ » Sun Jun 17, 2018 8:53 am

Cliff Jumper wrote:
Sun Jun 17, 2018 7:56 am
digits_ wrote:
Sat Jun 16, 2018 7:23 pm
You can easily check that yourself.
So, you're suggesting that this is soooo obvious that it is common sense and doesn't need to be written down anywhere?

There are quite a few (thousand) books on flight crew illusions, I just can't remember this in any of them. But, I fully admit, I might have missed it.
I wrote out the whole procedure how you can check it out yourself. Any pilot should be able to follow it. So yes, easy to verify if it is accurate.

I never said it was obvious. It is one of those things that usually don't matter.

If you disagree, let me know at which step it fails or where the error is.
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Re: WestJet almost puts one in the drink

#182 Post by Eric Janson » Sun Jun 17, 2018 2:31 pm

@digits_

Semantics maybe - but in reduced visibility you have marginal to no depth perception. You cannot accurately determine height and distance. This is why PAPI/Approach Lights/DME was invented.

@Cliff Jumper

Optical illusions discussed here - shortened horizon distance is mentioned.

https://www.skybrary.aero/bookshelf/books/812.pdf

The ALAR toolkit is worth downloading as it has a great deal of useful information
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Cliff Jumper
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Re: WestJet almost puts one in the drink

#183 Post by Cliff Jumper » Sun Jun 17, 2018 4:12 pm

Bit Eric, that reference gives the exact opposite of what you are saying. It says that in haze, you could interpret being too low, and pull up.
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Re: WestJet almost puts one in the drink

#184 Post by Eric Janson » Sun Jun 17, 2018 4:54 pm

Page 4 - Flight Path Monitoring.
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Cliff Jumper
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Re: WestJet almost puts one in the drink

#185 Post by Cliff Jumper » Sun Jun 17, 2018 6:31 pm

Still can't find the part where it says 'reduced visibility causes the illusion of increased pitch'.

But, granted, I don't read good.
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Re: WestJet almost puts one in the drink

#186 Post by Eric Janson » Fri Aug 24, 2018 12:13 pm

Final report released.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf

Lowest recorded altitude 39 feet! :shock: :shock:

Someone should send Lauren Stewart a copy of the report.
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Re: WestJet almost puts one in the drink

#187 Post by 98 Corolla » Fri Aug 24, 2018 12:29 pm

39 feet from what point on the aircraft?
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Re: WestJet almost puts one in the drink

#188 Post by Heliian » Fri Aug 24, 2018 1:23 pm

98 Corolla wrote:
Fri Aug 24, 2018 12:29 pm
39 feet from what point on the aircraft?
Wherever the source for the egpws comes from. I would guess a rad alt on the bottom of the fuselage.

That was an overly detailed report, they really pushed the paper well. No FDR data to go on either.
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Re: WestJet almost puts one in the drink

#189 Post by J31 » Fri Aug 24, 2018 3:04 pm

Eric Janson wrote:
Fri Aug 24, 2018 12:13 pm
Final report released.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf

Lowest recorded altitude 39 feet! :shock: :shock:

Someone should send Lauren Stewart a copy of the report.
That is the report that was released on June 4 2018 and Donald posted it that day. Eric we already hashed it out! :wink:
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Re: WestJet almost puts one in the drink

#190 Post by rookiepilot » Fri Aug 24, 2018 3:24 pm

Eric Janson wrote:
Fri Aug 24, 2018 12:13 pm

Lowest recorded altitude 39 feet! :shock: :shock:
Big deal. AC wins that contest.
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Re: WestJet almost puts one in the drink

#191 Post by Eric Janson » Fri Aug 24, 2018 9:56 pm

J31 wrote:
Fri Aug 24, 2018 3:04 pm
Eric Janson wrote:
Fri Aug 24, 2018 12:13 pm
Final report released.

http://www.bst-tsb.gc.ca/eng/rapports-r ... 7f0052.pdf

Lowest recorded altitude 39 feet! :shock: :shock:

Someone should send Lauren Stewart a copy of the report.
That is the report that was released on June 4 2018 and Donald posted it that day. Eric we already hashed it out! :wink:
Ok thanks - I missed that.
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Zaibatsu
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Re: WestJet almost puts one in the drink

#192 Post by Zaibatsu » Sat Aug 25, 2018 4:38 pm

rookiepilot wrote:
Fri Aug 24, 2018 3:24 pm
Eric Janson wrote:
Fri Aug 24, 2018 12:13 pm

Lowest recorded altitude 39 feet! :shock: :shock:
Big deal. AC wins that contest.
At night

Still on the vertical profile

On an offset lateral profile where lights were misleading

Nobody got a picture of that
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Re: WestJet almost puts one in the drink

#193 Post by C.W.E. » Sun Aug 26, 2018 2:35 pm

On an offset lateral profile where lights were misleading
I can understand that part of the problem the crew had in SFO because there are not many runways with airplanes on it pointed towards you with all those bright lights blinding you.
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Re: WestJet almost puts one in the drink

#194 Post by PostmasterGeneral » Sun Aug 26, 2018 2:43 pm

That brings up an interesting topic; the use of the taxi-light while holding short?

I always have it on anytime I’m away from the apron, provided it isn’t pointed directly AT another aircraft. Even when not in motion, I’ll generally leave it on unless giving way to another aircraft.

They’re usually aimed low enough that it won’t “blind” anyone else. What’s everyone else’s opinion on this? Looks like in the AC incident it helped a bit.
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Re: WestJet almost puts one in the drink

#195 Post by J31 » Sun Aug 26, 2018 6:10 pm

A lot of airline SOP's have the taxi light on when ever moving under power day and night.
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