What is the definition of "Sideline" in reference to aircraft noise?

Question

The FAA has measured external aircraft noise levels and published the results in the Advisory Circular:

AC 36-1H - Noise Levels for U.S. Certificated and Foreign Aircraft

In the appendices, noise levels are listed for Takeoff (TO), Sideline (SL) and Approach (AP).

I understand the concept of Takeoff and Approach, but what is "Sideline"? It is not defined in the document, nor does it show up in a search of the Code of Federal Regulations.

Your document mentions a 450m distance on page 3. See also http://adg.stanford.edu/aa241/noise/far36.txt mentioning more detail under C36.9(c) — BowlOfRed, Jan 22 '17 at 23:17
More on the noise measurement: Noise Certification Workshop and ICAO Doc 9501 Procedures for the Noise Certification of Aircraft — mins, Jan 23 '17 at 19:08

score 3 · Accepted Answer · answered Jan 23 '17 at 16:47

The definitions are specific. (They are defined in FAR Part 36). I'm writing also the Take-off and approach noise definitions just for your information.

Sideline noise: is defined and measured 1476 ft (450 m) from the runway centerline at a point where the noise level after liftoff is greatest.

Take-off noise: is defined as the noise measured at a distance of 21,325 ft (6500 m) from the start of the take-off roll, directly under the airplane.

Approach noise: is also defined and measured under the airplane when it is at a distance of 6562 ft (2000 m) from the runway threshold.

For each of these conditions the maximum noise level is a function of maximum takeoff gross weight, and for the take-off case the limits depend also on the number of engines.

What is the definition of "Sideline" in reference to aircraft noise?

1 Answers1