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Airbus Airspeed Indicator  
User currently offlineMb339 From Italy, joined Jun 2001, 238 posts, RR: 3
Posted (11 years 8 months 2 weeks 5 days 17 hours ago) and read 5511 times:

Could anyone explain me the symbols of the Airbus airspeed indicator?


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Thanks a lot!

mb339

7 replies: All unread, jump to last
 
User currently offlineFlightlevel From Canada, joined Jul 2003, 30 posts, RR: 0
Reply 1, posted (11 years 8 months 2 weeks 5 days 16 hours ago) and read 5493 times:

Are you talking just about the ASI? If so, the red shows the upper limit of speed, the yellow the lower limit of speed. If the speed gets close to either region, the computers will add or take away thrust and change pitch accordingly. The little green .780 shows the speed that the autothrust is set for. The green dot shows the no flap speed, at this you have to add flap or increase speed. Lastly, the little purple triangle shows the speed that you have selected to fly, and by referencing the diagram, it shows that they were just slightly slow.



User currently offlineRick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 51
Reply 2, posted (11 years 8 months 2 weeks 5 days 16 hours ago) and read 5495 times:

Some Airbus person will no doubt know all this but magenta triangle is clearly commanded speed (managed from FMGS I think). Blue triangle would be pilot-selected.

Red candy-stripe bar will be MMo and above (max mach #)

Yellow line shows current speed, yellow trend arrow shows speed in the next 10 seconds.

Green dot is minimum clean speed (flaps / slats up).

The yellow stuff towards the bottom gets you into protection / stall speeds and the like....



I used to love the smell of Jet-A in the morning...
User currently offlineRick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 51
Reply 3, posted (11 years 8 months 2 weeks 5 days 16 hours ago) and read 5491 times:

Just a quick correction to Flightlevel's post, I believe the .780 is the actual current Mach Number, rather than selected. Again not being an Airbus boff I can't say for sure but have jumpseated them enough times to remember that number fluctuates a bit... I'm sure it's the Mach Number indicator.

Also if it were a selected or managed value common sense would suggest it should be in blue or magenta... not green.



I used to love the smell of Jet-A in the morning...
User currently offlineFlightlevel From Canada, joined Jul 2003, 30 posts, RR: 0
Reply 4, posted (11 years 8 months 2 weeks 5 days 15 hours ago) and read 5476 times:

Right Rick, didn't catch that. It is the current Mach number.

User currently offlineGate Keeper From Canada, joined Jan 2000, 176 posts, RR: 0
Reply 5, posted (11 years 8 months 2 weeks 5 days 14 hours ago) and read 5476 times:

Mb339,

Symbols on Airbus ASI above are:

Red Band is high speed protection region with lower end being Vmo/Mmo.

Green equals sign (left of red band) indicates area where overspeed protection occurs. When it is activated, the pitch trim is frozen. Positive spiral static stability is introduced to 0° bank angle (instead of 33° in normal law), so that with the sidestick released, the aircraft always returns to a bank angle of 0°. The bank angle limit is reduced from 67° to 45°. As the speed increases above VMO/MMO, the sidestick nose-down authority is progressively reduced, and a permanent nose-up order is applied to aid recovery to normal flight conditions. The High Speed Protection is deactivated when the aircraft speed decreases below VMO/MMO, where the usual normal control laws are recovered. The autopilot disconnects when high speed protection goes active.

Magenta triangle indicates managed speed target.

Amber line indicates present speed(also indicated by green mach readout at bottom left) and arrow is speed trend for next 10 secs.

Green Dot (Engine-out operating speed in clean configuration)
This green dot appears when the aircraft is flying in the clean configuration. It shows the speed corresponding to the best lift-to-drag ratio.

Indented amber box on top of black and amber striped tape is called Vls. Vls is the lowest selectable speed that autothrust will allow you to fly.

The top of a black and amber strip along the speed scale indicates the alpha protection speed. It represents the speed corresponding to the angle of attack at which alpha protection becomes active. Alpha protection is not unlike over speed regime where autotrim freezes, pitch attitude is maintained at alpha max and full power (TOGA) is applied.

Hope this helps,
GK



User currently offlineSkystar From Australia, joined Jan 2000, 1363 posts, RR: 3
Reply 6, posted (11 years 8 months 2 weeks 5 days 11 hours ago) and read 5441 times:

See the small yellow arrow pointing downwards near 260, that's basically an accelerometer - showing the change in speed trend - the longer the arrow, the greater the magnitude in the change of speed.

It should indicate the speed you will have in 10 seconds at the current rate of acceleration.

Cheers,

Justin


User currently offlineGE From Singapore, joined Mar 2000, 320 posts, RR: 6
Reply 7, posted (11 years 8 months 2 weeks 5 days 3 hours ago) and read 5396 times:

The very botttom of the red bar is Vmax.
That is the lowest of:
-Maximum operating speed if in clean configuration (Vmo/Mmo)
-Maximum gear down speed if gear is down (Vle)
-Maximum flaps extended speed for current flap configuration (Vfe)

Regards,
Russell J.


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