White blocks at Flap positions on indicator
 

Hi all from sunny (sporadic) Banbury in UK. I have an on going question which the internet (and I've printed it all off, it's just not there) refuses to answer. As an aircraft ground engineer, it feels like a design/engineering thing. Why are there white blocks at the flap positions on the indicators? I feel like it's either for ease of pos identification or to allow for onload/offload flap positions?

Please put me out of my misery, I'm 64 and should be resting really ;)
https://cimg7.ibsrv.net/gimg/pprune....0d8fbd4174.png
757-300 flap indicator

Pre-digital? When flaps could be approximately the same, left & right, without undue worrying…

or, to account for (poor) pilot eyesight?

The gauges look familiar, and I think it’s for the situation when dealing with Flap drive failure checklist? “Flaps between 5 & 15?” etc. Anything in the white block counts as meeting the requirement.

There is a speed limit opposite of each white block. Maybe it's done just to facilitate "flap position - speed limit" identification.

It's to make it easier for partially sighted pilots.

The size of each block increases with increasing flap deflection. I would suspect the the size of the block shows the allowed indication error for a properly rigged aircraft.

That and the small notch in the white block is the where each particular indication is correct.

Rigging tolerance?

Alternate flap position bands , to aid crew when using alternate flaps not to be confused with primary and secondary .

Is it rigging tolerance between both sides, see the film on here about the flaps on YouTube.

Flight Controls

The blocks were there in the 737-100/200 family, before limit speeds were indicated on the panel next to the indicator:

https://cimg9.ibsrv.net/gimg/pprune....75a39ec15a.jpg
(from: Flight Controls)
Because of that, I tend to agree with the suggestion of rigging tolerances.

Thanks all
 

Thank you all who have replied so far, honestly didn't realise there were two needles on that gauge.

Yes 1.16 on the film shows them split