Vref headwind correction on a CJ2?

[Tired Soul]

In almost 2 years of flying a CJ2 I've only ever encountered one pilot applying a headwind correction to Vref :erm: and his background is the Regionals so that's probably where he picked it up.
Does it even make sense to do it for a CJ2 with a MLW of 11,500lbs?
What say you...yea or nea

 

[TigerDriver]

I'd say negative....Vref is a function of Vso..flight safety teaches Vtgt (target) which takes into account gusty winds and typically is Vref + some factor...

 

[Tired Soul]

Don't recall what the "book" says and I'm at home and don't have a spare copy.
CAE doesn't teach it that's for sure.

 

[340drvr]

Up front, let me say that I don't even begin to claim to have the definitive answer to this, but, I think TigerDriver's assessment is spot-on. Gust factor, sure, but not a general headwind correction. It really sounds like somebody has a serious misunderstanding of basic aerodynamic principles.

 

[Tired Soul]

My question is (partially) why bother?

Vref 104 in a no-wind is a GS of 104 and you're landing distance is taken from the table, let's say 2850'.
Now you have a 10 kts HW with no correction on Vref your GS is 94 and your landing distance will be less then 2850', increasing your safety margin.

If you apply a HW correction and therefore increase Vref you are increasing your GS again and getting closer again to your original number of 2850'.

I don't understand the purpose of this practice.

 

[TigerDriver]

Yeah you can't out in the weeds if you start correcting for headwind/tailwind etc. All the performance numbers (landing distances, obstruction clearances and such) are predicated on flying the AFM Vref speed. As a technique some pilots maintain Vref +10 as a margin of safety, although that can be excessive if you are going into a runway with limited distance.

 

[Tired Soul]

I'm aware of the effect of wind gradient and therefore a potential loss of IAS when descending into ground effect.
But from which windspeed would you even consider a HW correction factor?

 

[el raton]

I'm aware of the effect of wind gradient and therefore a potential loss of IAS when descending into ground effect.
But from which windspeed would you even consider a HW correction factor?

Lamding distance and brake energy.