Class A Airspace Overview

Key Characteristics

• Altitude Range:
  • Begins at 18,000 feet (Flight Level 180)
  • Extends up to 60,000 feet (Flight Level 600)
  • Covers the entire world above this altitude

Requirements for Entry

• ATC Clearance: Required to enter Class A airspace.
• IFR Certification:
  • Aircraft must be IFR (Instrument Flight Rules) certified, capable, and qualified.
  • Must be on an IFR flight plan.
• Transponder: Mandatory to have a transponder on board.
• Altimeter Setting:
  • Standard setting of 29.92 inches of mercury above 18,000 feet.
  • Use of flight levels instead of actual altitudes (e.g., say "Flight Level 190" instead of 19,000 feet).

Purpose of Standard Altimeter Setting

• Consistency Across Flights:
  • Ensures uniform altitude separation among aircraft.
  • Reduces the need for frequent altimeter resets.
• Pressure Altitude Usage:
  • Flights are based on pressure altitude rather than true altitude to maintain consistency and safety in altitude separation.