I need some help trying to figure this out from you bizjet experts out there.
Here's my example: A Gulfstream III (Stage 2) airplane AFM says that its certificated noise levels at max gross takeoff mass and at V2+10 are 103.4 EPNdb (sideline), 91.1 EPNdb (takeoff or flyover), and 97.3 EPNdb (approach).
Now let's reduce the takeoff weight. Obviously, the flyover and approach measures will both be reduced, and so will cumulative noise levels. Good news for the environmentalists.
However, at lower weights, V2 is
decreased. This means the time duration at V2+10 for the sideline measure will increase and the sideline noise will therefore
increase as well.
Solution? The noise regs allow us to use V2+10 to V2+20 for noise demonstrations. Fine. We schedule a climb airspeed transition to (for example) V2+18 instead. That means no noise increase at all, so the noise police folks are happy and accept the notion of "no acoustical change".
Bottom line questiuon: How do you feel about the new restriction of climbout at V2+18 vs. V2+10? Are there any operational downsides in your view? Or might it even be better (perhaps closer to Vy, improved climb)?
Your thoughts appreciated.
Cheers,
Tom