Airspace Classes Lecture Notes

Introduction

• Understanding airspace classes is essential for pilots.
• Airspace can be categorized as controlled or uncontrolled.
• Controlled airspace is managed by Air Traffic Control (ATC).

Controlled Airspace Classes

Class A Airspace (Class Alpha)

• Extends across the entire US from 18,000 feet MSL to 60,000 feet MSL.
• IFR (Instrument Flight Rules) only: requires an instrument flight plan and ATC clearance.
• Equipment required: Mode C transponder, ADS-B out, and DME above flight level 240.
• Speed limit: Mach 1.

Class B Airspace (Class Bravo)

• Surrounds 37 busiest airports in major cities.
• Depicted on sectional charts with solid blue lines.
• Altitude blocks with a floor and ceiling are listed in hundreds of feet MSL.
• Visualized as an upside-down wedding cake.
• Mode C veil: a 30-nautical mile radius requiring Mode C transponder and ADS-B out.
• Entry requires ATC clearance.
• VFR weather minimums: 3 statute miles visibility and clear of clouds.
• Speed limits: 250 knots inside, 200 knots below, and through VFR corridors.

Class C Airspace

• Found at large, less busy airports than Class B, typically in medium-sized cities.
• Depicted with magenta lines on charts.
• Structure: inner core (surface to ~4000 feet AGL, 5 nm radius) and outer shell (1200 to 4000 feet AGL, 10 nm radius).
• Cloud clearance: 1000 feet above, 500 feet below, 2000 feet horizontally.
• Speed limit: 200 knots within 4 nm of the airport; 250 knots below 10,000 feet MSL.
• Requires establishment of two-way radio communication with ATC.

Class D Airspace

• Found at airports less busy than Class C.
• Depicted with dashed blue lines on sectional charts.
• Resembles a cylinder: surface to 2500 feet AGL, 4-5 nm radius.
• Same VFR weather minimums and speed limit as Class C.
• Requires two-way radio communication with ATC.

Class E Airspace (Class Echo)

• Controlled airspace not classified as A, B, C, or D.
• Typically starts at 1200 feet AGL, can start at 700 feet AGL (transition areas) or surface in some cases.
• Vignettes on charts indicate floor changes.
• Rarely starts at 14,500 MSL (blue vignettes), extending to 18,000 MSL and above 60,000 MSL.
• No entry requirements, but VFR minimums vary above/below 10,000 feet MSL.

Uncontrolled Airspace

Class G Airspace

• Exists where controlled airspace doesn't, starting at the surface.
• Not depicted on sectional charts.
• VFR weather minimums below 10,000 feet MSL: 1-mile visibility during day, 3 miles at night.
• Cloud clearance: different below 1200 feet AGL and above it.

Conclusion

• Understanding airspace classes is crucial for safe flying.
• More airspace types will be covered in the next part.