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Project Experience: Examination of INM Accuracy, Denver and Minneapolis

The Challenge

Comparing predicted noise data at Denver and Minneapolis International Airports with actual statistical values.

The Strategy

HMMH conducted a study of over 20,000 data points of noise monitoring and radar data. This generated INM predicted single event levels by aircraft type. We then compared these predictions statistically with values measured for the same flights.

The average differences between computed and measured levels were determined for departures and arrivals of specific aircraft types and for different distances from the airport.

Values greater than zero mean that the INM predicts aircraft sound levels higher than measured, while values less than zero mean computed levels are less than the measured levels. For most of the aircraft studied at the two airports, INM departure values were generally 1 dB to 5 dB lower than the measured levels.