NADP and Flaps

[matj1986]

Hello,

So my question is :

Since NADP1 is used with close cities
And NADP2 is used with distant cities

Since in NADP1 Flaps are retracted after 3000 ft
And in NADP2 Flaps are retracted after 800 ft
And we know that No Flaps = steeper climb angle than with Flaps

Why do we retract Flaps later with close city ? arent' we closer to them that way ? Thus, making more noise ?

Regards,
Mathieu

[Tom]

Mathieu, the noise inflicted on the people below varies with the power setting and the distance (height) from the ground. You say ... and we know that No Flaps = steeper climb angle than with Flaps ... but for this to happen, you need to be at climb speed - the acceleration from V2 + 10kt to climb speed will not have a steeper climb angle.

NOISE ABATEMENT DEPARTURE PROCEDURE 1 (CLOSE-IN noise reduction)
This procedure intends to reduce noise levels close to the airport. It involves a thrust
cutback at or above a prescribed minimum altitude (800 ft) and delaying the flaps/slats
retraction no later than the prescribed maximum altitude (3000 ft). At the prescribed
maximum altitude, acceleration and flaps/slats retraction are performed according to
standard schedule while maintaining a positive rate of climb and then completing the
transition to normal en-route climb procedures.

NAPD 1 - thrust reduction as soon as possible after T/O, then climb at V2 + 10 all the way to 3000ft (keep climbing as fast as possible - any acceleration will delay the climb)

NOISE ABATEMENT DEPARTURE PROCEDURE 2 (DISTANT noise reduction)
This procedure aims at reducing noise levels further away from the airport. It involves
initiation of flap/slat retraction upon reaching the prescribed altitude (above 800 ft). The
flaps/slats are to be retracted in accordance with standard schedule while maintaining a
positive rate of climb. Acceleration targets the zero flaps safe maneuvering speed (VZF,
or S in the Airbus world) plus 10 to 20 knots (typically S+15). The thrust cutback is to be
performed simultaneously with the initiation of the first flap/slat retraction or when
CONF 0 is achieved. At the prescribed altitude (3000 ft AAL), the transition to normal
en-route climb procedures is completed.

NAPD 2 - accelerate and clean up as soon as possible, accelerate to VZF (clean) and climb to 3000ft, then accelerate.

Hope that helps

Tom

[Tom]

Interesting Boeing article:

http://www.boeing.com/commercial/aer...imb_story.html

Tom

[matj1986]

Okay, so basically :
NADP1 your reduce thrust early and clean later,
NADP2 you clean early and reduce thrust later.

Thanks a lot

[Tom]

Yep correct