The dark cockpit philosophy was originally developed by Airbus in the early 80s. The concept was first devised in the Airbus A310. The word ‘dark’ means that the aircraft switches and buttons remain dark or blank if things are working as they should. And if something were to go wrong, the switch lights up with a fault light.
Here is what Airbus A320 FCTM says about dark cockpit philosophy.
Most of the systems are controlled from the overhead panel via:
- Pushbutton
- Pushbutton switch
- Switch
- Knob, knob-selector.
Each pushbutton/pushbutton switch has one or two lights:
- The upper one is dedicated to alert or system status (e.g. FAULT light, OPEN light). If no alert or system status is required, two grey dots replace the light.
- The lower one corresponds:
- On pushbutton switch, to the control selection of the system (e.g. ON, OFF, OVRD), or
- On pushbutton, to the system status (e.g. ENG ANTI ICE).
If no control system selection is required, two grey dots replace the light.
The general operational rule is: Light out philosophy. The systems are ready and fit to fly.
PUSHBUTTON/PUSHBUTTON SWITCH LIGHT
The information provided on the pushbutton/pushbutton switch is also color coded to indicate the status of the system:
- Amber: Indicates that a system is failed
- Red: Indicates a failure that may require an immediate corrective action
- Green: Indicates that a system operates normally
- Blue: Indicates the normal operation of a temporarily selected system
- White: Indicates the abnormal position of a pushbutton switch or maintenance/test result indication
- Blank: The system is fit to fly.
Airbus switch light colour coding.
I would not agree with some answers here which states that all modern aircraft have dark cockpits. While fault lights that lights up on switches are a very common feature in aircraft, dark cockpits are found mainly in Airbus aircraft. ATRs follow the the same philosophy because it is partly owned by Airbus. So, it shares a lot of cockpit design and operational concepts with Airbus aircraft. Even the modern Boeings such as the 777 and the 787 does not have it. The 787 switches still when they are turned on has a light which says ‘ON’ or ‘AUTO.’ So, they do not really fit into the dark cockpit concept.
In the above pictures you have the overhead panels of a Boeing 787 and an Airbus A340 with fuel control panels marked. They are both flight ready. The 787 has ‘ON’ lights for the fuel pumps which confirms they are on. In the A340, the same pump lights are blank or dark when they are turned on. The latter shows the real dark cockpit concept, where a lights out condition shows normal operation. The advantage of a dark cockpit is the easiness of operation in a failure case. If for instance a fuel pump fails, the fault light of the switch will light up. And as all the other lights are out or dark, the pilots can easily see the pump with the fault.
It is easy for normal cockpit preparation as well. When you scan the overhead panel, you just check to see all the white ‘OFF’ lights are out to ensure everything is up and ready.
Author – Anas Maaz
