Question About Large-Aircraft Attitude Indicators

[jwp_145]

So I've noticed that on some large aircraft, say a KingAir or bigger, on the left side of the attitude indicator there is a diamond. Above it is says FAST, below it SLOW.

Anyone please tell me what it is there for?

Example

[JDE]

Anyone feel free to correct me if I'm wrong, but I think it's based on Angle of Attack. If you're "on", the green light, or circle in the case of the picture, will be centered. If the AOA becomes more flat, you'll get a 'Fast' indication or if the AOA becomes to steep you'll get 'Slow'. In our Falcon we can set the reference AOA - 1.3 Vso - for landing. In the Citation, I'm not sure what it's set to...probably something close to the same I'd imagine.

Anyone with anymore insight?

[launchpad]

that's exactly what it is. Basically it's an angle of attack indicator. It shows the relationship between actual airspeed and stall speed. Depending on the airplane, it's calibrated to a certain flap setting, or may even change indications based on actual flap setting. It indicates how close (faster or slower) to 1.3 Vs you are.

From what i've seen, it's a quick and easy way to see if you are at a proper speed for your configuration....definitely a good cross check of your calculated approach speeds.

[jwp_145]

Thankyou.

[AP2B]

I knew where and what the sensor was, but never knew where the indication was read... sweet.

[DE727UPS]

I always thought it was tied into commanded airspeed on your airspeed bug, or VNAV speed in the FMC. I never look at the darn thing, anways.....

[staplegun]

Originally Posted by launchpad

that's exactly what it is. Basically it's an angle of attack indicator. It shows the relationship between actual airspeed and stall speed. Depending on the airplane, it's calibrated to a certain flap setting, or may even change indications based on actual flap setting. It indicates how close (faster or slower) to 1.3 Vs you are.

From what i've seen, it's a quick and easy way to see if you are at a proper speed for your configuration....definitely a good cross check of your calculated approach speeds.

Depends on the plane.

On Boeing aircraft it's referenced to command speed, not AOA...



Kevin

[TFaudree_ERAU]

In our Lear it indicates fast/slow in reference to the bug on the airspeed indicator. Set the indicator to Vtgt for an ILS approach, and all you REALLY have to do is watch the fast/slow indicator to determine what your current speed situation is, along with all the other ILS data that is presented on the ADI. However, you'll probably always find yourself scanning the entire 6-pack as opposed to just the ADI.

[jwp_145]

Yeah seems to me like a target airspeed from the bug would be a little more helpful that AOA... that would just be another quick mental calculation you'd have to worry about.

[JDE]

Originally Posted by jwp_145

Yeah seems to me like a target airspeed from the bug would be a little more helpful that AOA... that would just be another quick mental calculation you'd have to worry about.

Just remember...you can stall at any airspeed, but always at the critical AOA. Using the AOA "gauge" is pretty helpful...a quick glance can let you know how close you are to your Vref speed and if you're getting close to a stall. As far as the F/S indicator...I never use the thing either...I'm going to make an attempt to try to start though. If it'll make my job easier, I'm all about it!

[Proud Pilot]

How come the bank indexes move in the OPPOSITE direction of your bank? I tried flying one of these on MSFS and crashed big time... I got all confused and to which way I was banking. Why do they make it so confusing? And what's that red/white stripy thing below the miniature airplane symbol?

[goredbirds]

Originally Posted by Proud Pilot

How come the bank indexes move in the OPPOSITE direction of your bank? I tried flying one of these on MSFS and crashed big time... I got all confused and to which way I was banking. Why do they make it so confusing? And what's that red/white stripy thing below the miniature airplane symbol?

Once you get used to it, the skypointer is a really neat tool. It took some adjusting to when I first started flying the RJ, because as you say, it moves in the opposite direction of your bank, but when you're in an unusual attitude, the skypointer is your best friend.

The red/white stripy thing is an inop flag. If the instrument is busted, that stripy thing appears and lets you know.