So from watching many videos in the cockpit on YouTube I have noticed that pilots will say stuff like "Loc Blue" or "2500 Blue" but what does this 'blue' mean and are there any other colours?
These images are form this video at 3:43 and 4:25.
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up.
Sign up to join this communitySo from watching many videos in the cockpit on YouTube I have noticed that pilots will say stuff like "Loc Blue" or "2500 Blue" but what does this 'blue' mean and are there any other colours?
These images are form this video at 3:43 and 4:25.
At the top of the Primary Flight Display (PFD, the one with the artificial horizon in the center), there is a so-called Flight Mode Annunciator (FMA) with several columns indicating currently active and armed modes of flight guidance:
The first line shows active modes (in this case: SPEED, ALT, and HDG) in green color. The second line has additional information about armed modes in blue color, which will become active later, for example LOC (localizer) mode will become active instead of HDG upon localizer capture.
The callout from the pilots like "LOC blue" serves to remind themselves of the current flight guidance modes, and to maintain awareness of mode changes. This is also to ensure that their mental idea of "what the aircraft will do next" is up to date and fits to the current flight situation.
However, I'm not sure about the "2500" you mentioned.
On youtube you can find videos like this one explaining a bit more about the FMA. (screenshot taken from there). As the comment by @DeepSpace mentions, the screenshot and video mostly apply to Airbus aircraft. Other aircraft may have similar displays about flight guidance modes, but I am not aware of their specific color codings.
Airbus uses "blue" in three different callouts, but with slightly different meaning.
"LOC blue" or "GS blue",etc, reffers to the armed modes of the F/D. It's just another way to say "localizer mode is armed and will be active once established on the signal"
"2500 blue" reffers to the altitude selection on the FCU. It specifies that 2500 feet have been selected, but blue here has a slightly different meaning: user selected altitudes are shown in blue on the PFD, where altitude constraints from the FMGS are magenta. A similar call eg. "4000 magenta" would imply "we will stop and capture 4000' because of a constraint"
"ecam memo?" "landing no blue" reffers to the landing (or t/off) memos displayed on the ecam. Uncompleted items appear in blue, completed in greeen. "no blue" here would mean, well, no incomplete items.
So as a quick answer: "blue" term means that something is displayed in blue on the screen