Executive Summary: NextGen was planned in 2007 for en route surveillance and route expansion for the National Airspace System (NAS). In 2005 there were about 70 hub airports where banks of 50 or more aircraft were scheduled by affiliated airlines to arrive and depart within the same hour or so.
The basic NextGen idea was to "extend" US airspace for flights that self-navigated from city to city. Using radar transponders to extend radar coverage already surveilled more airspace in 2007 than the pre-70’s radar systems. The transponders encode aircraft ID data in position responses, allowing air traffic controllers to guide more aircraft safely using computer-generated sector displays. However, the Terminal Radar Approach Control (TRACON) and airport implications for more arrivals per hour from more directions were seriously under-estimated.
Since February 2011, the South Metro Airport Action Council (SMAAC) has been communicating directly with FAA policy-makers about technologies planned for Minneapolis-St. Paul International Airport (MSP). Congressman Keith Ellison (D-MN5) was instrumental in opening this channel.
Next Gen’s Creeping Requirements. By 2007, navigation-aides were predominantly GPS based. The Next Gen premise was that ADS-B OUT transponders could 'report' GPS geocentric position to FAA En Route Centers. Aircraft could then ‘cut corners’ rather than flying under coverage from FAA Center to FAA Center. Their planned tracks would be displayed for Air Traffic Control use. Throughout the U.S. real and planned tracks theoretically could be sorted and displayed through a (computer) network.
For safety, the reliability and accuracy of aircraft navigation systems were determined and specified. FAA established a standard, Required Navigation Capability (RNC), and certification Performance-Based Navigation (PBN or PBN/RNAV).
Many aircraft had navigation systems on board to fly in bad weather or over areas lacking radar coverage. Some airports had long-range aRea NAVigation (RNAV) systems for approaches to airports and to transition into ILS runway systems. These systems were linked in some cases to autopilots for automated "blind" flying.
At MSP. MSP is small and urban. Overflight noise and pollution has always been an issue, often conflicting with airline plans. MSP adopted a CFR 14 Part 150 Noise Compatibility Plan in the 1970’s. In spite of some active flight restrictions, noise-exposure increased more than anticipated, and a sound-insulation program was instituted with a projected cost of about $500 million. The FAA approved the plan and several 5-year updates.
The airport commission operates “reliever” airports for charter, business, and general aviation use. Slower aircraft used MSP runways longer per operation. MSP minimum fees were high compared to the reliever airports. The diversion increased commercial carrier use of MSP per hour directly and cleared space for their and supporting business needs.
The FAA later adopted requirements met only by commercial airliners and newer business jets. This led to more uniform operations and more operations at close intervals. Capacity at MSP was based on Origin and Destination (O&D) passengers exceeding connecting passengers, and both this ‘hubbing factor” and operational noise agreements were threatened as use increased.
Projected air transportation service needed to support economic growth in the Twin Cities Metro and State through 2020 was the basis for a MSP study. SMAAC, the Minnesota Public Lobby, and various environmental agencies and groups worked toward a new airport. Northwest Airlines and MSP had invested in terminals and facilities at MSP over decades. Northwest accepted the 2020 capacity limit, perhaps intending to maintain its market dominance by limiting supply.
The expansion was mandated by the Legislature (based on costs, apparently under-estimated) in 1996. The final plan was approved (Final EIS) in 1998 by Minnesota and the FAA. The new runway, 17-35, was delayed in 2002 and completed in 2004. The new runway expansion was based on less than 850 flights per day and less than 120 operations per hour. MSP supported 540,000 operations in GFY 2005 and under a Consent Decree a few hundred more homes were “treated” to reduce noise impacts.
Today. Ongoing complaints signal that air pollution, cost, noise, safety, and planning issues are unresolved. This is caused mainly by the 50% reduction in connecting hubs following the airline mergers. Fewer connecting hubs led to overuse of MSP at peak hours.
After Northwest’s bankruptcy and merger with Delta Airlines, Delta changed schedules and aircraft to exploit MSP routes left open by other bankruptcies, mergers, and consolidations. Later, Southwest and Spirit added daily service at MSP. The changes led to overuse of MSP at peak hours. Use no longer matches the FEIS assumptions.
After a near-mid-air-collision in September 2010, routes and procedures were change by FAA “to reduce air crossings” for safety. The changes increased cost, noise-exposure, and pollution greatly in spite of fewer scheduled flights daily than 2005.
Air and Water Pollution. SMAAC and the World Health Organization warned that MSP operational rates increase health risk. Emission volume per flight and doses by concentration increase at low altitudes. Although the aviation industry lauds jet engine fuel efficiency, its claims of less fuel use overall are unsupported. The 50% reduction in connecting hubs increases fuel use and air pollution emissions in two ways. Safety at close intervals requires more time at lower altitudes or increased thrust or both; more complicated routes, flown visually or automated, are less fuel efficient and more polluting. City-hub-city routes are more than 200 hundreds miles longer on average, due to more back-tracking.
A Better Plan. FAA is driven by conflicting policies and unrealistic goals. The FAA plan was to use MSP runways “efficiently.” That is, operate as often as possible at minimum separations and maximally use the runways for arrivals. MSP however is not amenable for such a plan. Runway use is asymmetrical depending on the “flow” or direction of runway use. In NW flow, Runways 30L.30R.and 35 can receive arrivals. In SW flow arrivals are only on R12L/R.
 Airline system operations centers (SOCs) usually have network data communications with their in-flight aircraft. With yet-to-be-worked-out secure computer connections, FAA may be able to use airline data updates to tracks. However, network reliability and security requirements are strict, as they should be, and there is no Plan B for air traffic control outages.
 GPS position data can be compared to maps or past trips or flight plans (data bases). Any differences between the GPS position and the programed position (an error signal) can be corrected. An early application was flying a light plane between mountains In daylight, recording the track and following it at night or in poor visibility. The ATC application involves fast-moving obstacles, other aircraft. The Union of Concerned Scientists noted that N! Positions would be processed in each control interval. Initial NextGen was N = 150 (aircraft per sector), which the scientists thought way too many to compute and compare.