I have just joined the forum because I just can't figure this out. Before it gets worse and it robs me of my sleep, I thought I might find an answer here (no info on the internet so far).
So: I have recently flown on KLM's 787 "Sunflower" (PH-BHC), sitting in 42A. An hour into the flight I noticed that the armrest between 42A and 42B was different from all the other economy armrests that I could see. Instead of featuring a molded dark-blue top surface of rubbery material (best guess would be a thermoplastic elastomer (TPE)), the armrest was thicker and the top part was cushioned, made from sewn-together sheets of dark-blue plastic fabric (a bit like artificial leather, but tougher). I assumed it must have been a premium economy armrest. The armrest didn't have any special or additional function, all it had was the silver pushbutton to adjust the back of the seat. At first, I thought it might had been put there as a stopgap replacement until the correct economy armrest is available.
However, a little while later I noticed that on the tray tables on 42A and 42B, a genuine (as in labelled with a reference code) safety placard had been added to the existing symbols that describe the location of the life vests. The placard pictured an armrest with a semicircle arrow indicating the "fold back" movement in black. This scene was overlaid with a red crossed-out circle and probably meant "do not fold back the armrest". I was surprised, since the armrest folded back just fine, as I had found out before
I saw the placards.
Working in aviation, I was very curious to find out the meaning of all of this. I asked the cabin attendant if they could tell me something about it. They hadn't noticed the armrest or the placards yet, and they couldn't think of a reason. They did however ask their purser to come and have a look. The purser told me they had seen that the armrest is different, but hadn't noticed the placards either.
Now, here's what I speculated so far, but without conclusion.
1) The armrest is a temporary replacement until the right part is available. Cons:
- Since there are way more economy seats on the plane than premium economy (if any, I didn't check if there are such on KLM's 787 at all), I suspect there would also be a greater stock of replacement armrests, and so the use of a different armrest is unlikely.
- If so, I'm not sure if they would be compatible with normal seats.
- I see no reason why the replacement should not be folded back, hence no need to put placards on the tray tables.
2) The armrest serves a special purpose that prohibits it being folded up, e.g. a step to reach emergency equipment stowed overhead. Cons:
- Since 42A is the window seat, there is no need for a step to an overhead stowage, since one can only just stand under the hat racks.
- There is no equipment stowed (as the purser explained to me) in the vicinity of 42A, hence no need for a step.
- Even if a step is required, why would you not allow it to be folded back and why would it have to be padded?
Unfortunately, I didn't take any pictures of the armrest or the placards. Maybe someone who's going on "Sunflower" can have a look?
OK, let's see if we can solve this mystery together.