Why we need an MSP Flight Cap

After the September 2010 near-mid-air-collision, our recommendation became specific: louder turning departures may be somewhat safer, but the unneeded additional flight capacity is overly expensive. The result is an unnecessary and unwise increase in noise and pollution. 

In July 2010, we asked the Metropolitan Airports Commission (MAC) to seriously consider the World Health Organization (WHO) warning about increased health risks near busy airports. Our observation was that “busy” and “near” applied clearly to the MSP urban site and its use as a major hub. Federal law actually requires that lower cost alternatives be considered, and a cap on hourly rates of 130 or so operations at MSP until Next Gen deployment and 140 or so afterward would allow a per flight reduction in noise and pollution. .

The WHO found that health risks do not correlate with DNL contours. So, either the overflight risks to the over-flown populations are not “mitigated” by sound insulation, air conditioning, or better windows, or the maps are inaccurate, or both.  The noise exposure changes were widely complained about, and complaints increased again in 2011-12 by the runway-by-destination changes and additional departure headings. In two reviews, improperly modeled noise contours[1] were used to claim that the changed routes did not “increase (total DNL) noise compared with 2009 or 2004 operations.”


We had seen, and FAA confirmed, that R30R and R17 departures in and after 2011 were lower than the previous departure profiles for all runways by 200 to 400 feet as well as slower along their routes. 

  Although the 2007 Consent Decree settling the 60 DNL noise exposure treatment lawsuits specified an annual Actual Noise Report, the NOC accepted contour maps that assumed no changes in flight profiles compared to previous operations by route or runway. Also, the staff applied source noise values by projected fleet mix for future years, including less noisy new aircraft --a guess about airline purchases and their use at MSP Small changes in average source noise and the average number of flights per day per route were included in the yearly models.

  The MSP 2030 LTCP included a ground traffic analysis, based on daily flight increases, and costly projects, the roadway re-location and taxiway bridges, were planned. We commented that the purpose of the taxiway bridges was to allow faster gate-to-runway taxiing, a safety need whenever departure intervals were two minutes or less, which could be any quarter-hour, not a daily average. Comparing “DNL decibels” to noise intensity (loudness) in decibels and time overhead is fraudulent as mapped around MSP[2]

In 2012, the National Transportation Safety Board warned that near-simultaneous operations were “inherently unsafe” because runway headings in NW flow converged.  

  The Metropolitan Airports Commission (MAC) staff now says that flight operations, runway use and passenger capacity were not agreed upon for MSP Expansion by 1996 Law or as the basis for the 1998 Final Environmental Impact Statement (FEIS). In 1998, many aspects of environmental management were to be decided later, during large construction projects, as environmental regulations changed, or as economic needs were reconsidered.

  The MAC, in our opinion, did not properly consult with State and local environmental agencies. This led to a dozen or so controversial settlements and agreements allowing the MAC to decide upon the need for environmental reviews of all its own projects and operations. The permit limits for emissions of deicing chemicals to the Minnesota River is the only exception.

Arguably, at least, the State of Minnesota, through the MAC, and FAA agreed on an annual capacity of <640,000 operations through 2020, and a peak-hour capacity of 125% of 1996 use daily and at peak hours. After expansion, the new runway theoretically allowed an additional 40 operations, but these had to be all arrivals (NW flow) or all departures (SE flow). Hourly use of MSP is somewhat limited by gates and other facilities and controlled by the management of routes and schedules.

Since 2010, FAA has added routes and procedures for the connecting hub arrivals/hour goal that increase noise and pollution per flight. FAA is developing automated flight using PBN/RNAV and NextGen air traffic control at a great cost, but in the interim, managing safety risks in real-time in a variety of ways. The costs of this unneeded hourly capacity include the health risks and sound insulation as well as safety risks. 


[1] The noise exposure map comparing 2009 operations to 2010 operations misreported daily average differences because January through September operations were the same both years. For neighborhoods under the new departure routes, daily noise intensity was diluted 75% and under all other routes, reduced by fewer overflights.

[2] Comparing ground noise impacts in “DNL decibels” to decibels and time overhead is invalid. The “actual DNL values as mapped around MSP are not as accurate as a city block.


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