When Va is not always Va:
Certification standards and Va - Jetcareers
Go to that link for all the technical information you need for understanding the certification basis for Va.
Originally Posted by slipped
How do u guys explain the difference inpractical terms?
Now I don't think you care to here about published Va having the possibility of being published at a speed other than sqrt (limitloadfactor) * Vs. You did ask for practical terms, I suspect for explaining to a student pilot, not a training aeronautical engineer. Right?
In practical terms, maneuvering speed is a speed at which full control movements will result in no structural damage. I've yet to find an aircraft where published Va doesn't equal sqrt (limit load factor) * Vs, so, we can ignore that entire discussion when presenting this to a pilot.
Above Vno can simply be deemed as the speed to operate only when in smooth air. I.E. Smooth air penetration speed.
The limbo occurs with the question: When is there enough turbulence to require flight at Va versus up to Vno? IMO, you don't need to slow down to Va for light turbulence. I consider light turbulence still in the realm of 'normal' with respect to operating conditions. So my answer to this would be:
- Less than Va whenever you're in stronger turbulence (moderate to be safe IMO).
- Less than Vno whenever turbulence is light or better
- Greater than Vno whenever there is no turbulence