miscellaneos b 737

[uchy]

Hi guys, I have some question about the b737.
First of all, why in the overhead panel there are some white panel?and 3 red switch?what is the meaning of these different color?

An other question:
in the QRH about Airspeed Unreliable, the point number 4 say to cross check ground speed and winds to determine airspeed accuracy. How can I check if my IAS is good from the gs?
Thanks in advance

[hetfield]

Don't know 737, but GS and wind gives you TAS, so you can convert it to IAS.

[Johnny F@rt Pants]

Q1 - Sorry, I haven't got a clue what you are referring to, more description required, what does the white panel have on it, and what do the red switches have written on/next to them?

Q2 - My QRH, point 4 says - Cross check the IRS and FMC ground speed and winds to determine airspeed accuracy if indicated airspeed is questionable. By this it requires me to make required selections on the IRS panel to see what wind and speed are registering on there and cross check them against the FMC to attempt to deduce the unreliable indication.

[uchy]

thank you for your reply.
I try to explain myself better :
there are only 3 red switch ( alternate flaps, and 2 drive-disconnect), instead the background of fuel-generator-hyd-aircond are white..

why the reason of these different color respect the rest of the overhead panel?

[Checkboard]

http://www.pprune.org/tech-log/10181-b733-ohead-panel-colours-note-oz-spelling.html

http://www.pprune.org/engineers-technicians/50178-737-overhead-panel.html

If you pull a fire switch the systems on the affected engine (or APU) which will be cut off or isolated are those controlled by the switches on the lighter colored panels. In the 737NG it's Fuel, Electrical, Hydraulic fluid flow, and Pneumatics.

[Callsign Kilo]

To be more specific,I believe point 4 from the QRH NNC for 'Airspeed Unreliable' relates to a possible failure of 2 or more pitot inputs. It could be a case where you have been subjected to 2 or 3 contradicting sources of IAS. The third memory item to crosscheck the IAS or Mach displays in order to identify the spurious source will have proven fruitless. The most important thing of all is to assume control of the aircraft. In a climb or descent simply fly a pitch attitude and a thrust setting to resume level flight. I have witnessed this failure in the sim on numerous occasions. The potential for confusion and eventual loss of control is untold. Some similarities can be observed with the unfortunate Air France A330 accident a few years back.

[Capt Chambo]

I like the answers in Checkerboard's links.

One other option I heard years ago for the light grey panels was that they were the minimum that you need to configure/set up/get right before take-off!

3 Red Switches:- need crew confirmation before actioning, once actioned they are irreversible. (To paraphrase the QRH preamble)