Why can't aircraft follow roadways?
Aircraft arriving to and departing from any airport are under the guidance of the Federal Aviation Administration (FAA) and established aircraft operating procedures. Under certain flight conditions, aircraft are unable to navigate using ground references because of weather or limited visibility, speed of aircraft, and/or other operating environment considerations.
For example, aircraft operating at MSP are directed by FAA Air Traffic Controllers continuously to ensure maximum safety and efficiency. The combination of fast-moving aircraft and multiple runway options at MSP contribute to a complex airspace and airport environment. A system of flight procedures are customized for MSP to keep aircraft separated from one another in good and poor weather conditions. The MSP operating environment requires that pilots follow the established flight procedures rather than ground references to ensure a safe and orderly flow of arriving and departing aircraft:
- Arriving aircraft use a long straight-in approach path, known as a final approach. An Instrument Landing System (ILS) is used for the final approach at MSP, which provides lateral and vertical guidance to the runway end. Signals are emitted by ground equipment and received by the aircraft at a precise angle and slope while descending. This is why there is little variation in the approach path.
- Departing aircraft at MSP are dispersed over a wide area, much like a "fan" in order to maintain safe and efficient use of the airspace. The fanning that takes place is a result of runway assignment, aircraft performance, destination airport and airspace congestion at the moment of departure.
These methods are FAA standards used at airports throughout the national airspace system. The FAA publishes flight procedures for all airports on its website here: Digital Flight Procedures.