Question for the ones who knows aviation history

[Joselito]

Hello, my first post here. I think if I can't find a official answer here, will not find anywhere else.

Well, it all started when I posted the attached picture on my facebook wall and someone asked what were those 3 white "bubbles" under the landing light switch. After the question, I realized that all commercial airplanes has this design for the landing lights, regardless of the manufacturer - I saw it on Embraers, Douglas, Airbus, Boeings, Lockheed, etc. I checked the FAR part 25 to look for an answer, but could not find any. Does anyone know the history behind these 3 white dots?
tip: They glow in the dark (phosphorescent material). Thanks for any help.

[I_FLY_LOW]

The most reasonable answer I read was from here:
http://www.airliners.net/aviation-fo...read.main/2078
"The "T" design is there so you can gangbar the switches to the on or off position.

That's All"

[rwanttaja]

My guess is they're visual confirmation on what the switches are for, like the wheel-shaped landing gear switches and flap-shaped flap switches. The three dots are like the landing lights as seen by another aircraft.

Ron Wanttaja

[Bob Dingley]

I,m with Ron. The little "dots" are filled with the same kryptonite that mark the exits. If DC powered, they would not be visible in a power failure. Oh shucks, neither would the lights themselves. All mfgs buy their switches at the same switch store.

BTW, everybody knows what that little cross between the wing lights and nose lights means?

[Joselito]

My guess is they're visual confirmation on what the switches are for, like the wheel-shaped landing gear switches and flap-shaped flap switches. The three dots are like the landing lights as seen by another aircraft.

Ron Wanttaja

Hi Ron, thank for your input. I am with you as a visual confirmation, I just don't know the origin. The wheel-shaped landing gear lever and airfoil shaped flap lever has an origin on FAR part 25 and it remounts to accidents in the past, but those 3 little dots have no information on any FAR. I found on PPRUNE forum another explanation that makes sense: back in the day, without back-lit instruments, there was flood lights to illuminate the cockpit panels, including the overhead. During approach at night, the flood would cause glare in the windshield, so pilots would turn off the overhead lights, but those three dots would still be visible in the dark. That makes sense too, I just don't know whether it's true or not.

BTW, everybody knows what that little cross between the wing lights and nose lights means?

That I know It's the position of the connection point behind the light-plate.

[FlyingRon]

The woman across the taxiway from me at CJR has one of those switches on the lights in her Navion. Sort of cool (I've just got a regular toggle). Neither is original to the Navions. Of course, she also had a baby food jar for the belly strobe light lens. I thought that was somewhat distinctive, but she had it replaced with a proper lens.

[Jim Hann]

Hello, my first post here. I think if I can't find a official answer here, will not find anywhere else.

Well, it all started when I posted the attached picture on my facebook wall and someone asked what were those 3 white "bubbles" under the landing light switch. After the question, I realized that all commercial airplanes has this design for the landing lights, regardless of the manufacturer - I saw it on Embraers, Douglas, Airbus, Boeings, Lockheed, etc. I checked the FAR part 25 to look for an answer, but could not find any. Does anyone know the history behind these 3 white dots?
tip: They glow in the dark (phosphorescent material). Thanks for any help.

If you look at the row of light switches in a 747-400 each type of light has a different shaped switch handle. My understanding was so that you would know which switch you switched without looking. The 757/767 have those push buttons instead for lights other than the landing lights.