There is a change in take-offs patterns over Minneapolis and North Richfield. This change undoes an earlier procedure adopted in 1998 to reduce noise in these areas "so close to the airport". Using a letter of concern from FAA as an excuse, MAC decided to implement increased use of runways 30L and 30R at busy hours by allowing higher climb rates and faster departures for many aircraft types.
Use of the parallels has increased since 1998, and today 30% more planes fly over Southwest Minneapolis than were projected in the plan approved in 1994. In a statement to the MAC Noise Oversight Committee, Chad Leqve, Noise Control Manager at MSP, said that this change, based on an FAA rule requiring "all aircraft over 75,000 pounds ... to meet Stage II noise emission standards", would "shrink the 60 DNL 2005 unmitigated contour". So what? This is not 2005. NOC voted to accept the change, SMAAC believes, because the city representatives mostly didn't understand the presentation, and the airline representatives did [see below].
If all aircraft using MSP in 2005 meet Stage III noise emission standards, that would "shrink" noise contours all around the airport, whether or not the take-off procedure is changed. There are other assumptions under consideration for 2007 that lead to projected noise reductions.
OK, there is some difference due to the new procedure alone. In general, it increases noise near the airport and decreases it away from the airport. All other things being equal, the noise reduction in the "60 DNL area" is quite a bit less than the increase in the 75 to 65 DNL areas. Mr. Leqve chose not to share that this year and every year, actual noise exposure has increased compared to the contours projected for 1996. Noise apologists figure that more noise is acceptable if "mitigated", that is, buildings torn down or sound-insulated. But the Part 150 Program goal was attenuation to at least a 45 dbA noise level inside a treated building. The new take-off procedure might actually increase noise on the ground by more than 1.5 dbA. The regulation then requires a new noise exposure map. The MSP DNL model has not been officially computed since before 1994. MAC is delinquent. MAC is hoping to cover its butt for a decade of non-compliant use by announcing a new plan for noise compliance in 2007.
SMAAC notes that Wenonah School and several other buildings mapped in the 68 or 69 DNL areas could be in the 70 or 75 DNL area after this change if a noise contour map were drawn for 2003 actual use and actual fleet mix. In fact, the official map is so removed from reality, its assumptions so far off target, that it differs significantly from contour maps drawn in 1998 for the EIS. MAC also claims airport noise has been reduced overall and will be re-distributed and reduced further in Minneapolis, North Richfield, Mendota Heights by 2007. This claim is a fabrication, with a phony noise exposure map based on far-fetched assumptions now being foisted on MSP's neighbors.
Safer Alternatives. Remember that FAA letter? It actually said the take-off procedure needed to be changed if increased hourly peak rates were continued. Beyond the "60 DNL" distance from the airport, a faster plane might overtake a slower plane originally 2 miles ahead in about a minute. FAA records incidents where airliners close to less than one mile, and these incidents have increased every year since 1995. Why? Because MSP is busier at peak hours.
MAC might have refused the change, reducing noise, but also limited flights per hour to a safer level. FAA controllers could hold the next, faster, aircraft on the runway until the one ahead was safely gone. It is perhaps of more concern that this change &Mac246; allowing more peak hour use &Mac246; passed through MAC's Operations Committee without raising questions about capacity, ground safety and congestion; without considering any alternatives.