FAA Aircraft Dispatcher Practice Exam

Which altitudes is an IFR Low Enroute chart used for?

1. Below 10,000 ft

2. Up to but not including 18,000 ft

3. From 15,000 ft to 20,000 ft

4. Above 18,000 ft

The correct answer is: Up to but not including 18,000 ft

An IFR Low Enroute chart is designed for navigational use in the altitude range from the surface up to, but not including, 18,000 feet. This chart provides important information for pilots operating under instrument flight rules, including navigational aids, airways, waypoints, and some terrain features. The range up to 18,000 feet is significant because it corresponds to the transition between lower altitude airspace and the higher altitude enroute structure. Below this altitude, aircraft often operate in controlled airspace with specific routing and procedures, and the chart facilitates safe navigation and situational awareness for IFR flights. Higher altitudes or those above 18,000 feet belong to a different classification of enroute charts, known as High Altitude Enroute charts. These cater to aircraft operating in more extensive controlled airspace at higher elevations, where routes and navigational aids differ in presentation and relevance to air traffic management.