Boeing 787 Seat Adjustment

[dmwalker 607]

I have a question arising out of the discussion of the recent LATAM B787-9 flight LA800 incident. Attention is now focussing on a horizontal control switch on the upper back of the pilot's seat, which can be used to move the seat forwards and backwards. It has been suggested that the switch could have been accidentally activated, moving the seat forward until it pushed the control column forward to the point where the autopilot was disengaged.

My question is why is this switch necessary? Surely the seat is always left in the rearward position by the previous pilot. 

Also, why would the seat be able to travel so far forward that it could interfere with the position of the control column?

 

 

Edited March 15 by dmwalker

[scott967 62]

Well, it seems this switch is unique to 787 so assume there must have been operator feedback that it would be "nice to have".  I don't think you would randomly increase parts count just to add cost of production.

 

scott s.

.

 

[dmwalker 607]

2 hours ago, scott967 said:

Well, it seems this switch is unique to 787 so assume there must have been operator feedback that it would be "nice to have".  I don't think you would randomly increase parts count just to add cost of production

Maybe it's for when the pilot has a medical emergency and has to be removed from the seat as quickly as possible without disturbing the pedestal controls. The standard switch might be awkward to reach in an emergency.

Edit: One of the YouTube comments explains the purpose of the switch. I should read the comments more often:

"Hey Juan, I spent the last 6 years before retirement on the 787.  The switch on the back of the seat is used primarily to move the seat forward and aft to give you room to put your kitbag in place or get it out after the flight."

Also:

"Finally, the way the seat is made with the yoke cut-out in the front of the bottom seat cushion, there isn't anyway for the seat to contact the yoke and move it.  With all that said, I don't see how you could trap a meal tray between you and the yoke because the seat simply doesn't move that fast electrically. When I first heard about this,  my first thought was that a crew member possibly slipped and fell onto the yoke, when getting in or out of the seat causing the nose over - which I still think is what most likely happened."

Edited March 16 by dmwalker

[Matthew Kane 1,343]

This one is a strange one, after the incident I guess the pilots were saying the flight computers kept cutting out, and then now it was the seat malfunctioned, but yea it really could be a pilot error and they didn't now what to say about it at first, of course we don't hear or see what happens in the investigation, which is being handled by New Zealand so we will see what happens in the end

Edit: It is looking more now like the steward probably just put their hand on the back of the seat, and even though that switch has a cover you can still actuate that switch by pushing on or putting pressure on the cover, and that causes the seat to move forward, so not a pilot error. 

Edited March 16 by Matthew Kane

[jon b 2,050]

That electric switch on the back of the seat is actually very handy, it saves having to bend down to reach the switches on the side of the seat when getting in.

There is also a master switch on the side where you can turn the electric seat functions off.

Even at full forward you shouldn’t be pressing against the yoke, unless of course you have a meal tray on your lap, or you’re of a larger size, I suspect one or both of these factors may be in play in this scenario.

Edited March 16 by jon b

[dmwalker 607]

8 hours ago, Matthew Kane said:

It is looking more now like the steward probably just put their hand on the back of the seat,

But I think the seat would move forward only while you are pressing the switch. If you put your hand on the back of the seat and it started to move, you would automatically remove your hand, wouldn't you? Based on the QualityWings 787, it takes about 10 seconds for the seat to move from the fully back and outward position to the fully forward position. That should be enough time to react. 

[dmwalker 607]

2 hours ago, jon b said:

That electric switch on the back of the seat is actually very handy, it saves having to bend down to reach the switches on the side of the seat when getting in.

Could this become a standard feature for other aircraft or does the 787 have it because of some unique feature of the cockpit layout?

[jon b 2,050]

The seats are actually made by a company in the U.K. I believe, the same company that made the 747 seats.

The switch is just a convenience feature, nothing more, it’s nothing specifically required for the 787, I guess they just designed a new seat and thought it would be a nice feature to add. 
It’s only purpose is to make it easier to get into the seat when getting onboard, or indeed to get someone out of the seat if incapacitated, however cabin crew are taught to only use the manual levers to bring the seat back, in case the electric function isn’t working.

Edited March 16 by jon b

[goates 576]

1 hour ago, dmwalker said:

But I think the seat would move forward only while you are pressing the switch.

There seems to be an issue with loose switches, and it doesn't need to be held down to continue moving.

 

Edited March 16 by goates

[dmwalker 607]

1 hour ago, goates said:

There seems to be an issue with loose switches, and it doesn't need to be held down to continue moving.

So, perhaps a more robust switch assembly would solve the problem but, as far as I can see, all that is going to happen is the switch will become one more item on a checklist or a recommendation to revert to manual mode when in flight. I wonder if the cabin crew know the location of the power cutoff switch. It looks as if it's easier to reach from behind the seat.

[Matthew Kane 1,343]

13 hours ago, dmwalker said:

But I think the seat would move forward only while you are pressing the switch. If you put your hand on the back of the seat and it started to move, you would automatically remove your hand, wouldn't you? Based on the QualityWings 787, it takes about 10 seconds for the seat to move from the fully back and outward position to the fully forward position. That should be enough time to react. 

Yes as been said, the rocker switches can get loose so therefore possible to activate the switch when you just put your hand on the cover, which is likely what the steward did which is innocent enough. Boeing has issued a bulletin to address this issue.

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