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flyingturtle
Topic Author
Posts: 6069
Joined: Mon Oct 31, 2011 1:39 pm

F-S scale on the attitude indicator

Wed Apr 14, 2021 11:08 pm

I just wondered about this thingy here...

https://commons.wikimedia.org/wiki/File ... orizon.jpg

What does the

F
_

-

-
_

S


scale on the left mean?

My guess is "Fast - Slow", but that can't be...
Reading accident reports is what calms me down
 
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Starlionblue
Posts: 20605
Joined: Fri Feb 27, 2004 9:54 pm

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 12:19 am

Image

My guess is that it is an angle of attack index, and the letters do indeed mean Fast and Slow. Many fast jets use angle of attack as a reference on approach.


You can see the index on the left of this F/A-18 HUD.

Image

F-16.

Image

You can see the same on the Airbus BackUp Speed Scale (BUSS) which appears if you've lost significant parts of your air data. The speed scale becomes purely an AoA reference.

Image
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SoCalPilot
Posts: 113
Joined: Fri Mar 17, 2017 4:37 am

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 2:37 am

Its an angle of attack indicator and the F means Fast and the S means slow. Used primarily for maintaining landing speeds but can also be used for initial climbout speeds.
 
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flyingturtle
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Joined: Mon Oct 31, 2011 1:39 pm

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 8:12 am

Thank you all! :cheerful:
Reading accident reports is what calms me down
 
thepinkmachine
Posts: 458
Joined: Tue Apr 28, 2015 4:43 pm

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 12:17 pm

Depends on type. On ATR and older 737 / 767 (before speed tape was introduced) it was speed deviation from reference selected speed on the Airspeed indicator. It was quite useful
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
744lover
Posts: 207
Joined: Mon Nov 06, 2000 5:29 am

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 3:52 pm

thepinkmachine wrote:
Depends on type. On ATR and older 737 / 767 (before speed tape was introduced) it was speed deviation from reference selected speed on the Airspeed indicator. It was quite useful


Same for the Classic 747 series....

Image
 
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flyingturtle
Topic Author
Posts: 6069
Joined: Mon Oct 31, 2011 1:39 pm

Re: F-S scale on the attitude indicator

Thu Apr 15, 2021 5:01 pm

Wow, thanks again!

This makes my FlightGear insanity a bit... more comfortable.
Reading accident reports is what calms me down
 
VSMUT
Posts: 5389
Joined: Mon Aug 08, 2016 11:40 am

Re: F-S scale on the attitude indicator

Fri Apr 16, 2021 7:04 am

thepinkmachine wrote:
Depends on type. On ATR and...


Indeed, displayed on the EADI:

Image

IMO, easier to work with than the speed tape of the -600, but lacks all the other useful stuff the speed tape comes with.
 
LimaFoxTango
Posts: 1003
Joined: Wed Jun 16, 2004 11:33 pm

Re: F-S scale on the attitude indicator

Fri Apr 23, 2021 11:46 pm

On the Dash 8 100/300 there was a Fast/Slow indicator which was referenced against 1.3Vs (1.3 times stall speed) for current configuration (ie flap setting) which was the center mark.....IIRC
You are said to be a good pilot when your take-off's equal your landings.
 
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Horstroad
Posts: 569
Joined: Thu Apr 08, 2010 8:19 pm

Re: F-S scale on the attitude indicator

Sun Apr 25, 2021 9:20 am

flyingturtle wrote:

My guess is "Fast - Slow", but that can't be...


Your guess is correct. It's an indication for the current air speed in relation to the speed set for the auto throttle / speed command system.

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