GPS vastly improves situational awareness for both visual and instrument flight rule
(VFR and IFR) flying, reducing circuitous travel and airspace incursions. As importantly,
GPS provides an instrument approach capability for airports that in the past have not had
either the ground-based navigational aids (NAVAIDs), and/or terrain that supported an
instrument procedure. Evolutions in avionics and satellite navigation systems have
improved accuracy and alerting capabilities, which result in smaller integrity limits.
Smaller integrity limits allow smaller obstacle evaluation areas (OEAs). Smaller OEAs
reduce the potential for obstacles. Since obstacles raise approach minima, the smaller the
chance of obstacles, the greater the opportunity for lower minimums. If you have the proper
equipment, you can take advantage of these new procedures. A circling approach is actually
a procedure based on the aircraft's approach category, not the source of the navigational
aid signal. Therefore, circling minima do not change between different types of approaches
to the same airport.
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