# For pilots- noise abatement question **URL:** \ **Category:** Factual Questions\ **Created:** [October 22, 2010, 1:12pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999 "2010-10-22T13:12:15Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![MikeF](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@MikeF](https://boards.straightdope.com/u/MikeF)\ **Post date:** [October 22, 2010, 1:12pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/1 "2010-10-22T13:12:15Z")
I was just reading an article wherein a pilots says, when flying out of John Wayne Airport, the jet must become a ballistic missle just after taking off due to noise abatement procedures. Does he mean they have to climb steeply to clear the sensitive areas by a certain altitude? It would seem to me that high power settings at low altitude is what the noise abatement is trying to prevent. Just how steeply can a bizjet (or heavy for that matter) climb if passener comfort is not a consideration? I’m not talking about gathering airspeed and the yanking it up at the last second. At normal take of speeds, what’s the steepest climb you can maintain? ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [October 22, 2010, 2:23pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/2 "2010-10-22T14:23:17Z")
It seriously depends on the aircraft, temperature, air pressure/density, and other things. But what your pilot is talking about is actually turning off the engines, so as to become a free-falling projectile. He gains momentum during early climb-out, then uses that to launch himself up to a higher altitude. Then he can power up again to regain airspeed. To give a really ballpark figure, 25 degrees pitch-up is a pretty steep climb. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [October 22, 2010, 2:32pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/3 "2010-10-22T14:32:33Z")
A normal take-off with no noise abatement would use sufficient thrust to take-off from the runway in question and shortly after getting airborne the climb becomes more shallow, the aircraft accelerates and the flaps and slats are retracted. The power would be reduced to the climb setting and the aircraft continues to accelerate. The result is that the aircraft will be at a lowish altitude when flying the initial departure over the noise sensitive areas. A typical noise abatement procedure might have you maintain a high powered, low speed, high rate of climb until you reach a certain altitude then the aircraft might be accelerated to the appropriate speed for zero flap, cleaned up and climb power set. The climb will then be continued at the minimum safe climb speed at zero flap, going for a steeper climb rather than the higher speed in the normal take-off. The power won’t be any higher than in the normal take-off but the speed is lower and so the climb is steeper. The aircraft will have the same climb power setting as in a normal take-off but will be much higher when overflying the noise sensitive areas. The steepest climb they can maintain is pretty much what they get in the very first part of the take off, the first few hundred feet. [Here is a chart with rotation angles and climb angles of various aircraft.](http://3.bp.blogspot.com/_ugWk-rnkqXM/Sg2PVuPJW8I/AAAAAAAAFM8/5Fij_FAiRN4/s1600-h/Boeing_Rotation_and_Lift_off_All_Aircraft_Models_All_Engines.gif) The steepest is the MD11 at 25 degrees. V2 refers to the minimum speed to fly with one engine out. Speeds such as V2+10 are the initial climb speeds with all engines operating and the associated body angle given in the chart will achieve that speed. So to climb at V2+10 the MD11 should be pitched up to a maximum of 25 degrees. On a normal take-off the V2+10 speed would only be maintained to 400 feet and then the aircraft would be accelerated and cleaned up. In a noise abatement climb you might climb at V2+10 to 1000’ then clean up and continue the climb at the minimum speed for zero flap. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [October 22, 2010, 2:34pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/4 "2010-10-22T14:34:03Z")
> [@Chessic\_Sense](#): > > It seriously depends on the aircraft, temperature, air pressure/density, and other things. But what your pilot is talking about is actually turning off the engines, so as to become a free-falling projectile. He gains momentum during early climb-out, then uses that to launch himself up to a higher altitude. Then he can power up again to regain airspeed. The “ballistic missile” bit is just a figure of speech, they don’t really go ballistic or reduce the engines to idle or anything like that. ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [October 22, 2010, 3:32pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/5 "2010-10-22T15:32:02Z")
> [@Richard\_Pearse](#): > > The “ballistic missile” bit is just a figure of speech, they don’t really go ballistic or reduce the engines to idle or anything like that. Yeah, I know. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [October 22, 2010, 3:46pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/6 "2010-10-22T15:46:15Z")
I’ve found the ICAO noise abatement procedures, they are examples only and each manufacturer will have more detailed procedures that suit their aircraft. Anyway ICAO have two procedures, one for noise sensitive areas near the airfield and one for areas further away. For the near airfield one, at not less than 800 feet the power is reduced, the airspeed maintained at V[sub]2[/sub]+10-20 knots, and the flaps left in the take-off configuration until 3000 feet at which time the aircraft accelerates to enroute climb speed and the is cleaned up (flaps and slats retracted.) For the further away one it is much the same except at not less than 800 feet the aircraaft accelerates to the zero flap speed (V[sub]ZF[/sub]) and the flaps and slats are retracted, it then climbs at V[sub]ZF[/sub]+10-20 knots until no higher than 3000 feet at which time it accelerates to the enroute climb speed. The first one results in a steeper angle of climb to 3000 feet but it’s worth noting that the first 800 feet of both of the climbs is not only the steepest but is also the same as a normal take-off. Here’s a little bit from [Wikipedia](http://en.wikipedia.org/wiki/John_Wayne_Airport#Aircraft_noise_abatement_and_curfew) about the noise abatement at John Wayne Airport. > [@](#): > > The short primary runway (19R/1L), coupled with the local noise restrictions, can require a takeoff at or near full power (95-97% power). Some aircraft departing from the airport may cycle to full power while holding at the runway then release the brakes when engines are fully spooled up. On operations from runway 19R a steep climb may also be required to allow for a power reduction at about 500–700 feet AGL for quieter overflight over the city of Newport Beach. For 19R departures a left turn after departure to 175 degrees allows for a passage over Newport Beach within the confines of the noise abatement profile. Departures from 1L (normally during Santa Ana wind conditions) are not affected by these noise abatement procedures. Landings almost always include the use of reverse thrust. > [@Chessic Sense](#): > > Yeah, I know. Ah good then. ---
**Author:** ![MikeF](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@MikeF](https://boards.straightdope.com/u/MikeF)\ **Post date:** [October 22, 2010, 5:30pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/7 "2010-10-22T17:30:18Z")
Got it. As a glider pilot the primary noise that I try to abate is the one I hear as I am leaving home. Soaring seems to do it, albeit only temporarily. Thanks. ---
**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\ **Post date:** [October 22, 2010, 5:49pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/8 "2010-10-22T17:49:37Z")
Just flew out of SNA (I’ve used it before). Pilot makes a steep climb at maxpower then cuts back the throttle and lowers the nose. If you are not ready it is really a hinky experience culminating with a “We’re gonna crash!!!” feeling. I can see where the ballistic anology comes from. ---
**Author:** ![Sandra\_Battye](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sandra_battye/32/552_2.png) [@Sandra\_Battye](https://boards.straightdope.com/u/Sandra_Battye)\ **Post date:** [October 22, 2010, 8:24pm UTC](https://boards.straightdope.com/t/for-pilots-noise-abatement-question/557999/9 "2010-10-22T20:24:22Z")
SNA is my favorite airport for just this reason! Maybe not a E ticket but a lot fun anyway.