VLS in landing configuration
Thread Starter
Joined: Sep 2016
Posts: 15
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From: EYVI
VLS in landing configuration
good day
a little bit confused about VLS on airbus. here is the definition of VSL in OM
VLS : Lowest Selectable Speed.
Represented by the top of an amber strip along the airspeed scale on the PFD.
Computed by the FAC, based on aerodynamic data, and corresponds to 1.13 VS during
takeoff, or after a touch and go.
Becomes 1.23 VS, after retraction of one step of flaps.
Becomes 1.28 VS, when in clean configuration.
Note: If in CONF 0 VLS were 1.23 VS (instead of 1.28 VS), the alpha protection strip
would hit the VLS strip on the PFD.
Above 20 000 ft, VLS is corrected for Mach effect to maintain a buffet margin of 0.2 g.
In addition, VLS increases with speed brakes extension.
but there is nothing written about VSL in landing configuration with config 3 or full. so my question is what is the factor of Vs the VSL representing in landing conficuration?
a little bit confused about VLS on airbus. here is the definition of VSL in OM
VLS : Lowest Selectable Speed.
Represented by the top of an amber strip along the airspeed scale on the PFD.
Computed by the FAC, based on aerodynamic data, and corresponds to 1.13 VS during
takeoff, or after a touch and go.
Becomes 1.23 VS, after retraction of one step of flaps.
Becomes 1.28 VS, when in clean configuration.
Note: If in CONF 0 VLS were 1.23 VS (instead of 1.28 VS), the alpha protection strip
would hit the VLS strip on the PFD.
Above 20 000 ft, VLS is corrected for Mach effect to maintain a buffet margin of 0.2 g.
In addition, VLS increases with speed brakes extension.
but there is nothing written about VSL in landing configuration with config 3 or full. so my question is what is the factor of Vs the VSL representing in landing conficuration?
Joined: Apr 2010
Posts: 1,319
Likes: 100
From: IRS NAV ONLY
In the same chapter (PRO-SUP-10), take a look at the Vs - stall speed:
So, VREF is 1.23 VS1g and VREF is VLS in CONF FULL, so VLS is 1.23 VS1g in any configuration with flaps extended except during takeoff.
Don't blame yourself, it's the way Airbus manuals are written.
Authorities allow aircraft of the A320 family to use the following factors:
‐ V2 = 1.2 × 0.94 VS1g = 1.13 VS1g
‐ VREF = 1.3 × 0.94 VS1g = 1.23 VS1g
‐ V2 = 1.2 × 0.94 VS1g = 1.13 VS1g
‐ VREF = 1.3 × 0.94 VS1g = 1.23 VS1g
Don't blame yourself, it's the way Airbus manuals are written.
Thread Starter
Joined: Sep 2016
Posts: 15
Likes: 0
From: EYVI
yes I have read this but what makes you think that Vls in landing config = Vref? could you point where it is provided? thanks
upd. I found it by myself. thanks anyway
upd. I found it by myself. thanks anyway
Last edited by Pilotas; 1st December 2016 at 15:24.
