Hi guys,
Definition of VWS:-
"Vertical wind shear in knots per 1000ft at the respective waypoint and is calculated using the forecast wind 1000ft above and below the waypoint.
Moderate CAT may be encountered if the value exceeds 6, especially when accompanied by a horizontal wind shear greater than 18 knots per 150 NM and / or a temperature gradient greater than 5°C"
From my limited experierence, the VWS act as a guide should you need to do a CRZ climb or descent in the region. Basically, it tells you about the Wind characteristics above and below your PLANNED CRZ LEVEL. You might encounter aome turbulence if you are climbing or descent in an area with VWS greater than 6.
To forecast if there's any turb, I will first look at the significant charts, look out for any CAT area and significant cloud prediction along my flight plan.
Next, I will look into the LIDO CFP for any significant OAT changes and ISA changes at the SAME LEVEL. This will show if we are flying through different airmass and it will increase the probability of encountering any CAT.
LIkewise, if we are flying through an area with significant cloud activities, we can be certain that it an area of unstable air conditions which equate to possible turbulent conditions.
Any comments?
Cheers,
lion-g
Last edited by lion-g; 21st May 2011 at 06:25.