Lighting
The lighting systems on the 737NG are separated into four categories:
- Flight deck and cabin lighting
- Exterior lighting
- Emergency lighting
- Cabin Signs
Flight deck lighting
All overhead indicator lights and some lights on the forward instrument and aft electronic panel on the flight deck can be dimmed, brightened, or tested using the LIGHTS switch located on the left forward instrument panel.
The FD has two incandescent dome lights. The two lights are on the P6 and P18 panels - the latter of which has dual lamps, one for normal operations and one for emergency operations as a backup. These are controlled by a three position switch located in the Aft Overhead panel - OFF, DIM, and BRIGHT.
Flood lights are placed to provide specific area lighting for the glare shield, forward instrument panel, and the centre pedestal.
The control for the glare shield flood lights are on the left side of the forward instrument panel, and it is labelled AFDS (Autopilot Flight Director System). Next to the AFDS kbos is the BACKGROUND knob, which controls the incandescent lighting for the CA’s, FO’s, and centre instrument panel.
On the centre pedestal there is a FLOOD light knob that controls the overhead spot light directed at the control stand. Next to it is the PANEL knob, which controls the integral lighting for the aisle stand.
Overhead integral lighting is controlled via the PANEL light control on the overhead panel.
Additionally, each station has a MAIN PANEL light control. The CA’s MAIN PANEL knob controls the brightness of the center instrument panel, glare shield displays, edge lighting, and CA’s instruments.
The FO’s MAIN PANEL only controls the FO’s panel brightness and instrument lighting.
Each sidewall panel has controls for MAP and CHART lights associated with each position. Additionally, each pilot and each jumpseat has a semi-portable utility light that can be released for handheld operation.
The adjustment of the brightness of each display unit is controlled by a combination of light sensors - located left and right on the top of the glare shield to compensate for ambient light - and brightness controls. Additionally, each display unit has its own built-in light sensor.
Cabin lighting and signs
The primary cabin lighting controls are located on the Forward Attendant Panel, near the front passenger entry door (L1).
Normal cabin lighting illuminates:
- Seats
- Aisles
- Entryways
- Lavatories
- Galley Areas
- As well as call lights and passenger information signs.
From the Flight Deck Passenger Signs Panel on the overhead panel the Fasten Belts switch controls both the SEATBELTS and RETURN TO YOUR SEATS passenger signs. It is a three position switch with an AUTO mode, which illuminates the signs when flaps or gear are extended. Likewise, the lights will extinguish when the flaps and the gear are retracted.
External lights
Navigation lights include wight lights aft of each wingtip. These are controlled by the POSITON switch on the overhead panel.
There are two red anti-collision lights on the top and bottom of the fuselage, while white strobes are located on each wing tip. Note that the white strobes seem to be in addition to the white position lights.
Forward of the fuselage there are WING light switches used to check for ice on the engine nacelles and wing leading edges.
Fixed landing lights are installed at the wing roots and are controlled by the FIXED Landing light switches. There are also RETRACTABLE landing lights that are controlled via a three position switch - stowed, deployed, ON. Note: Late -800 series aircraft have the taxi light incorporated into the wing root and not on the nosewheel. Additionally, these aircraft also remove retractable landing lights.
The difference between fixed landing lights are retractables is that the FIXED lights are positioned to illuminate the runway during the flare and ground roll portions of a flight, which the retractable landing lights are parallel to the waterline of the aircraft. These are controlled by the RETRACTABLE light switches, and may be deployed at any speed.
The aircraft also has two runway turnoff lights for additional lighting during ground operations. The L and R RUNWAY TURNOFF switches control them.
The taxi light is mounted on the nose wheel strut and always points in the direction of the nose wheel (see note above about late model 800 series aircraft.)
Above the horizontal stab there are flood lights to illuminate the tail.
Each wheel well and the nose gear also have lights installed. They are controlled with the WHEEL WELL switch. The nose gear light can also be switched on from the external comunications panel, while the main gear wheel well lights can be switched on from the left main gear area.
Emergency lights
Emergency lights can be controlled from the flight deck or the aft CCM panel (the latter overrides the flight deck switch). IT is here in case of a failure of the automatic control system
Emergency lights will illuminate automatically if electrical power to DC Bus 1 fails of the AC power has been turned OFF while the EMER EXIT LIGHTS are in the ARMED position.
On standby power, the following lights illuminate:
- Standby magnetic compass light
- Emergency instrument flood lights
- Battery bus automatically powers CA’s dome light
Additionally, the emergency lighting system supplies sufficient cabin lighting for quick evacuations. Normal lighting is replaced by lights and signs powered by the batteries, which are installed near the exits and charged by the electrical system.
Cabin emergency lighting consists of door, aisle, escape path, and exit lights, as well as exterior lights at each entry door, over-wing exit, and on escape slides.
How many dome lights are there in the flight deck?::Two dome lights controlled by P6 and P18. The latter has dual lamps as an emergency backup.
Where can you find replacement bulbs for indicator lights?::Above the FO’s position.
How are the displays’ brightness controlled?::Via two remove light sensors on top of the glare shield and the brightness controls. Can you turn on the main gear wheel well lights from the exterior?::Yes, using the switch located in the left main gear area.
What causes the emergency lighting to come on?::Failure of DC Bus 1 or AC power turned OFF if the EMER EXIT LIGHTS are in the ARMED position.
What lights will be on in the flight deck if power is lost?::Standby compass light, instrument flood lights, CA dome light. How long will emergency lighting last on battery power?::At least 10 minutes.
Can you test indicator lights on the 737NG?::YEs, using the LIGHTS switch on the forward left panel.
Which stations control the emergency lighting system?::Flight deck switch and Aft Attendant panel.