The above chart shows the sideline noise of narrow-body jet (including turbojet and turbofan) powered airplanes measured in EPNdB, which is a scale for Perceived Noisiness Level. That being said, leaps and bounds have been made since the first commercial jet airplanes. That's one of the primary reasons why city airports haven't flourished as well as people have thought back in the 70s. If you google sound scale, jet noise is pretty much always near the top. Jet noise has been known to be notoriously bad. If you lived near an international airport with commercial traffic, then it couldn't possibly have been sonic booms, as others have noted. Like rolling thunder instead of the bomb-like or cannon-like dull thud of an explosion that is a sonic boom. In the case of engine noise, you will continue to hear the noise as the aircraft fades into the distance. Just aircraft noise with a perceived increase in intensity as it thunders past you. You don’t hear it coming, then BOOM! Unfortunately, that is still not a sonic boom. When close to the ground, it is almost like a fighter jet is sneaking up on you in silent mode until it passes you in a great and sudden cacophony of sound. Though, even at subsonic speeds, the effect can be quite jarring. Small military jets (not transport or cargo) sometimes operate at higher speeds along specific routes or in specific areas. Both Stage 1 and Stage 2 helicopters are allowed to fly within the U.S.” In addition, by December 31, 2015, all civil jet aircraft, regardless of weight must meet Stage 3 or Stage 4 to fly within the contiguous U.S. In addition, aircraft at or under 75,000 pounds maximum take-off weight must meet Stage 2, 3, or 4 to operate within the U.S.
Currently within the contiguous US, civil jet aircraft over 75,000 pounds maximum take-off weight must meet Stage 3 and Stage 4 to fly. ”The FAA has undertaken a phase out of older, noisier civil aircraft, resulting in some stages of aircraft no longer being in the fleet. “In 1990, Congress passed the Aviation Noise and Capacity Act, which required that by the year 2000 all jet and large turboprop aircraft at civilian airports be Stage 3.” The FAA and ICAO has taken further steps to reduce the actual noise produced by aircraft according to FAA.gov, The aircraft will climb quicker to altitude, descend later from altitude, or turn away sooner, thereby reducing the effect of aircraft noise in neighboring communities. Speaking of closer to the ground, modern Noise Abatement Procedures have made it so large turbine powered aircraft avoid overflying populated areas at low altitudes. Much more rumble-like after passing due in part to Doppler effect and the aircraft being closer to the ground when landing. Like hearing a race car at full-tilt passing you on the sidelines. But, the sound seems to be much more intense and at a lower (bass) frequency after it has passed rather than when it is approaching. (a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).Īt those speeds, you can hear the aircraft coming. You would have to get special permission from FAA leadership (not ATC controllers) to otherwise perform such a stunt. As Niels has pointed out, civilian aircraft are prohibited from operating faster than 250 knots Indicated Airspeed below 10,000 feet MSL in most cases. It was either not a sonic boom, or it was not a commercial jet.
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