The Noise Compatibility Plan (NCP) at DTW combines the existing approved Part 150 Noise Compatibility Plan with Air Traffic Control Tower (ATCT) requirements to ensure the safe and expeditious handling of air traffic. While safety is paramount to any aircraft operation, noise sensitivity to the surrounding communities is also of key importance in airport operations.
Flight Procedures/Runway Use
The Federal Aviation Administration (FAA) is responsible for determining under what conditions flight operations may be conducted without causing degradation of safety. Under ideal conditions aircraft takeoffs and landings should be conducted into the wind. Considerations such as delay and capacity problems, runway length, approach aids, noise abatement, and other factors may require aircraft operations to be conducted in a specific manner.
The ATCT at DTW is managed by the FAA and determines runway use based on achieving safe aircraft operations in compliance with FAA regulations. Weather, wind direction and speed, visibility and cloud cover, schedule load, and noise abatement procedures are all considered when the FAA determines which procedures will be operated at any given time at the Airport. As conditions change or are predicted to change, such as weather, ATCT responds by adjusting procedures to ensure safe and efficient operations.
Through the approved NCP and continued coordination with the ATCT and airline operators, DTW operates under a preferential runway use program. Presently, the preferential runway use for the Airport is to concentrate noise over the less densely populated areas south of the Airport, by directing departing aircraft to the south, with quieter arrivals from the north. Although aircraft are generally directed into the wind, preferential runway program calls for southern departures with up to a 7-knot tailwind to maximize the availability of this procedure. Data shows that the Airport operates in south flow (departing to the south and arriving from the north) about 68% of the time, north flow (arriving from the south and departing to the north) about 30% of the time, and the crosswinds (east/west) about 2% of the time.
Between the hours of 11:30pm - 6:00am the ATCT seeks to operate in reverse flow (also called head-to-head or contra flow) by having departures to the south as well as arrivals from the south. This procedure only applies to nighttime operations, and depends on availability of the airfield.
The majority of the time, the outboard runways (of the four parallel runways, the outboards are the outer east and west runways) are used for arrivals, while the inboard runways are used for departures. Runway use can be aircraft type specific, meaning that different aircraft have different runway uses based upon aircraft size, performance, and location relative to the passenger terminal gates.
In addition to implementing noise abatement runway use procedures, the ATCT direct the departing aircraft in a “fanning” procedure to disperse the noise to reduce impacts on noise sensitive areas. Preferential noise abatement flight tracks have been designated for aircraft departures that disperse or “fan” over noise sensitive land uses.
Noise Generated during Aircraft Engine Maintenance & Ground Run-Ups
Airlines must regularly conduct maintenance or repairs on aircraft systems and engines. For certain types of aircraft maintenance, engine run-up tests are conducted to demonstrate that the aircraft's in-flight systems are working properly before the aircraft can be put back into service. A run-up is a preflight test of the engine systems, where various levels of engine power are applied while the aircraft remains stationary. A substantial amount of noise can be created during run-up tests.
In an attempt to limit noise intrusions on our DTW neighbors all aircraft perform their run-ups in a Ground Run-up Enclosure (GRE). This is a three sided facility in which an aircraft performs the maintenance check, or run-up. The sound is absorbed into the walls and deflected upwards, rather than outwardly into communities.
The DTW Ground Run-Up Enclosure is located between runway 4L/22R and runway 4R/22L.
Noise Complaint Response
Noise complaints are evaluated to identify the cause of the noise event and determine if an aircraft is operating outside the noise plan parameters. Noise complaints are not necessarily reflective of the severity of the noise, but can be useful to the Airport in identifying problems and issues that are important to the various communities surrounding the Airport.
DTW’s Noise Compatibility Program Hotline is available 24 hours a day to receive public comments and complaints by calling (734) 942-3222.