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 D. FAA Aircraft Stage Classifications:

The FAA classifies aircraft into three stages for clarification: Stage 1, 2, and 3 in order from loudest to quietest.  Noise levels for Stage definition of aircraft are measured at three points.  These points are designed to measure noise levels for take-off, approach, and flyovers (sideline).  Furthermore, classification is also based on the number of engines.  FAA uses FAR Part 36 for further details of Stage clarification and Noise Term Definitions. 

             Stage 1:

A Stage 1 noise level means a take-off, flyover, or approach noise level greater than the Stage 2 noise limits.

 
             Stage 2:

Stage 2 noise limits for airplanes regardless of the number of engines are as follows:

For Take-off: 108 EPNdB for maximum weights of 600,000 pounds or more, reduced by 5 EPNdB per halving of the 600,000 pounds maximum weight down to 93 EPNdB for maximum weights of 75,000 pounds and less.

For Sideline and Approach: 108 EPNdB for maximum weights of 600,000 pounds or more, reduced by 2 EPNdB per halving of the 600,000 pounds maximum weight down to 102 EPNdB for maximum weights of 75,000 pounds or less.

 
             Stage 3:

Stage 3 noise limits are as follows:

For Take-off: airplanes with more than 3 engines 106 EPNdB for maximum weights of 850,000 pounds or more, reduced by 4 EPNdB per halving of the 850,000 pounds maximum weight down to 89 EPNdB for maximum weights of 44,673 pounds or less.

For Take-off: airplanes with 3 engines 104 EPNdB for maximum weights of 850,000 pounds or more, reduced by 4 EPNdB per halving of the 850,000 pounds maximum weight down to 89 EPNdB for maximum weights of 63,177 pounds or less.

For Take-off: airplanes with fewer than 3 engines 101 EPNdB for maximum weights of 850,000 pounds or more, reduced by 4 EPNdB per halving of the 850,000 pounds maximum weight down to 89 EPNdB for maximum weights of 106,250 pounds or less.

For Sideline: regardless of the number of engines 103 EPNdB for maximum weights of 882,000 pounds or more, reduced by 2.56 EPNdB per halving of the 882,000 pounds maximum weight down to 94 EPNdB for maximum weights of 77,200 pounds or less.

For Approach: regardless of the number of engines 105 EPNdB for maximum weights of 617,300 pounds or more, reduced by 2.33 EPNdB per halving of the 617,300 pounds maximum weight down to 98 EPNdB for maximum weights of 77,200 pounds or less.