8. Climb, Cruise, and Enroute

After takeoff, Tower hands you to Center unless the flight is short enough to go directly into the arrival flow.

Center handles:

• Initial airborne contact.
• Climb clearances.
• Heading/vector instructions.
• Direct-to and waypoint sequencing.
• Center handoffs when required.
• Top-of-descent transition into descent/arrival.

Altitude planning now uses sparse flight-level data. Not every waypoint has a fixed flight level. Climb and descent controllers manage intermediate clearances, SID restrictions, cruise, descent, and approach targets as the flight progresses.