1902 - 120th Place SE #202

Everett, Washington, 98208

Phone: (425) 337-9472 or toll free (888) 300-5443; Fax: (425) 337-9578

A flight test consists of the test aircraft flying over the test site at various heights. Typically the aircraft flies a race track 

flight path around the test site.

Noise data is recorded simultaneously at 3 positions on the test site. Weather data is recorded on the ground and in the

air using a small aircraft (i.e. Cessna 172). Aircraft position data is typically acquired using DGPS, but picture or video 

scaling can be used. Click to see a schematic of the data acquisition. 

The data is extrapolated to reference conditions based on the certification rules. Noise-Power-Distance (N-P-D) databases 

are then derived for Takeoff, Sideline and Landing conditions.

To calculate the Certification Noise Levels

1. Determine Reference Day Profile (click to see schematic)

2. Enter N-P-D at reference distance and power.

3. Determine Certification Noise Levels from N-P-D

   • Takeoff, Sideline, Landing

4. Compare with Stage 3/Chapter 3 Limits

5. If any exceedances, adjust for trades

   • Exceedance at any one point < 2 dB

   • Sum of any 2 Exceedances < 3 dB

   • Sum of all 3 Exceedance < 0 dB

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