San Lorenzo Citizens Fighting Airport Noise


Techniques Pilots Can Use to Minimize Aircraft Noise


The following is a portion of "The Noise Police Are Here: What You Can Do About It," by Peter A. Bedell, published in AOPA Pilot Magazine, August 2001, Vol. 44, No. 8 (http://www.aopa.org/pilot/features/2001/noise0108.html). Bedell was a captain for a regional airline and former technical editor of AOPA Pilot.



The most obvious way pilots can win the noise battle and perhaps save their troubled airport is to reduce their noise footprint, a term used to describe the path of airplane's noise. Pilots have to fly responsibly and realize the consequences of their actions. For example, making 10 circles over your house at 500 feet agl only proves that your freedom is now intruding on the lives of all your neighbors. It should also be the responsibility of all flight instructors to remind their students to be aware of the noise that aircraft create. The following are some techniques to keep in mind:

Keep propeller rpm to a minimum. Most of the noise from a typical general-aviation airplane comes from the propeller, the tips of which at maximum rpm can approach the speed of sound. Keeping the propeller rpm of a constant-speed prop lower drastically reduces the amount of noise your airplane generates. Reduce propeller rpm as soon as practical after takeoff. Most normally aspirated Lycoming and Continental engines permit "oversquare" operation despite the old wives' tale that manifold pressure should never exceed the rpm in hundreds. With this in mind, leaving the throttle full and decreasing rpm by 200 reduces power only slightly but greatly reduces the noise output.

When arriving at an airport, do not advance the propeller control to high rpm until the propeller falls out of governing range. There are few sounds more annoying than those that come from a pilot who advances the propeller control fully forward while on a downwind leg in the pattern. In a high-powered single like a Beech Bonanza or Cessna 210, this makes an ear-piercing racket that can be heard from miles away. In addition, the rapid change in sound may lead the uneducated to think that something is wrong with the airplane.

Climb at the best-angle-of-climb airspeed. For airplanes equipped with fixed-pitch propellers, the only practical method of reducing the noise of the airplane is to place the maximum amount of distance between the airplane and those on the ground. Climbing at the best-angle-of-climb speed (VX) helps place hundreds of feet of altitude between your airplane and the neighbors. Of course, pilots of airplanes equipped with constant-speed props should also use this technique in conjunction with reducing rpm. Pilots of twin-engine airplanes should climb at the best-single-engine-rate-of-climb speed (VYSE) for the best combination of climb rate and safety. An in-house study at AOPA showed that the association's Beech A36 Bonanza was more than five decibels quieter over the departure end of the runway if the rpm was reduced to 2,500 and the airplane climbed at VX, compared to a flatter climb at the maximum 2,700-rpm setting. Pilots are also encouraged to avoid intersection takeoffs, which place the airplane at a lower altitude when crossing the airport fence.

Avoid low, dragged-in approaches and wide traffic patterns. Except in special circumstances, flying a traffic pattern at a lower than normal altitude is unnecessary, especially when the airplane is configured with gear and flaps down early in the pattern. It takes cruise power or higher to maintain altitude with all of that drag hanging in the breeze. Besides, other pilots are looking for traffic at the same altitude in the pattern, not 300 feet below it. In general, keep the pattern tight, and don't leave the traffic pattern altitude until abeam the threshold or when turning your base leg.

Familiarize yourself with the airports that you visit and where possible, follow voluntary noise-abatement procedures. An airport that has voluntary noise-abatement procedures has already endured a noise battle with its local community. Not following the voluntary procedures gives still more ammunition to the citizens at the next town meeting. Know the traffic pattern design and altitude for the airport prior to your arrival. Many airports utilize nonstandard traffic patterns in an attempt to reduce noise complaints. Right-hand patterns or those that take the airplane over industrial areas rather than housing developments are becoming more common. At some local airports, the unicom operator usually reminds inbound aircraft of special procedures for example, flying their downwind leg 1.5 miles south of the airport at a higher than standard altitude in order to appease the local citizens. Unfortunately, when pilots ignore this reminder on a daily basis, the airport manager gets the phone calls.

CFIs must be proactive in teaching friendly flying techniques. Flight instructors are the front line of defense in the noise battle. Urging your students to comply with the above techniques will help ensure your airport's survival and possibly the security of your job. In addition, CFIs should take students to airports in more rural areas to perform touch and goes. When teaching turns on or about a point it would be prudent to not always use the same reference point and to try to avoid populated areas.

Pilots need to be salesmen to the public when it comes to aviation. Ignorance is aviation's worst enemy. Land use policies are often ill-conceived, and pilots should be quick to point out to the community that housing developments planned for construction near the airport are irresponsible. When faced with such situations, pilots should offer to take city officials or members of the media for a ride so that they can see and experience the consequences of such plans.

Noise is the number-one reason for airport restrictions, operational limitations, or outright closure. In addition, local governments often deny approvals for airport safety improvements such as longer runways and instrument approaches because they are persuaded by the local residents' fear that larger, noisier aircraft will destroy their peace and quiet. With this in mind, pilots have to realize that we are treading on thin ice.

The fact that piston aircraft powerplants are as noisy as ever while jets are getting quieter reinforces the fact that noise problems are going to become an ever-increasing clamp on where, when, and how we can fly. In order for the aviators of tomorrow to enjoy this passion, we must make efforts to get along with the local community. We must also realize that noise is an issue that affects aviation across the entire country, not just in the local community. Out of earshot, out of mind is the name of the game when it comes to avoiding a call from the noise police.