Altittude knobs A320
 

Hi guys
Why A320 altitude, V/S , heading and speed knobs are completing a turn with 32 click ?

[guess mode]
Because thats what sensor that could be bought off the shelf that was proven safety critical?
[/guess mode]

Always find it hilarious why people want to know such info , even worse if TRIs are asking such questions to students during training

On the A330 it has 33 clicks a turn as far as i know.

A few years on the bus and i never bothered to find out how many clicks it is. It is virtually useless knowledge in my opinion. But then, if it makes you happy...

"Clicks per turn"
 

More important to understand what the particular "knob" does and how to confirm that movement of it has resulted in the intended setting, I think.

Using the inference in Wiedehopf's post I guess the A380 has 38 clicks. I am joking of course.

I'm afraid to even ask how many clicks the 787 has... :}

Well it may not help much knowing the answer but one rotation of HDG knob in A320 it is 32 degrees, it says nothing about altitude knob but VS/FPA is again 32 degrees, in A330 it is HDG 30 degrees. It says nothing about altitude knob and FPA it is again same as A320, 32 degrees one full rotation.

On checks we get asked the duty cycle of the stick shaker motor! Vilas, you need not reply! ;)

;)

For Altitude and Speed select, Concorde used what look like bog-standard "35mm camera film rewind" knobs with fold-out cranks. In an era before digital-push-button FMC flight plan entries, it was probably nice to be able to whizz-whirr one's target altitude up to or down from 60K feet with a rapid crank.

(Concorde pros can comment)

http://www.concordesst.com/inside/co...tures/ap17.jpg
http://www.destoutz.ch/slides/typ_nm...ob_black_2.jpg

When it comes to the number of clicks per revolution in today's knobs - some "human factors" engineer probably had to figure out the optimum number to allow fast adjustments (more clicks per turn), while retaining discrete spacing of clicks for fingertip precision (fewer clicks per turn).

And came up with "32-ish."

In the RAF, an IR renewal always asked what the rpm of the turn and slip gyro was. I know it had 27 in it; 27/270/2700/27000; who cares? Wholigan asked me...(Mil forum).

32 click control knobs ? Have Airbus run out of the 64 click knobs?

32 is a number that comes up often in computing - 32 bit registers were used often in early computing for example. Perhaps it was an easy way for those early, 1980s vintage computers to register inputs?

http://en.m.wikipedia.org/wiki/32-bit

I'm going to twiddle my non-bus knobs this arvo and see if they're 32bit or 64bit!

Rather than how many clicks per revolution of the knob, a more useful thing to know is how much does the target quantity change per each click?

From memory I think Airbus FBW is as follows, (but will check next time I fly):

SPD 1 knot or 0.1 Mach per click
HDG: 1 degree per click
ALT: 100' per click or 1000' per click depending on the setting of the scale selector
V/S: 100' or 0.1 degree FPA per click

Let us know where and when you are going to do this checking and we'll make sure we are watching on Flightradar....:ok:

Are the knobs single rate or dual rate?
If dual I hope you know the rate required to change from fine to course adjustment!

Reminded of the joke about knobs in cockpits :}

My HDG knob is ten clicks per 360.

Bit of a worry when you don't know what each click selects, Uplinker!

Well it wouldn't be much use if each click was 2 degrees would it....

"Turn right 5 degrees"..... "err sorry can you make that 4 or 6 degrees" :}