Descent Profile

A Descent Profile is the planned vertical flight path from cruise altitude to the initial approach fix (IAF) or final approach. It defines when to begin descent (Top of Descent), descent rate, speed schedule, and any level-off segments.

• Top of Descent (TOD): Calculated by FMS based on distance, altitude, speed, and winds
• Rule of thumb: Multiply altitude to lose (in thousands) by 3 for distance in nautical miles
• Idle descent is most fuel-efficient (engines at flight idle, gravity provides energy)
• ATC may assign crossing restrictions ("Cross FIXXX at FL240")
• Speed brakes are used if the aircraft is high on the descent profile
• CDA (Continuous Descent Approach) profiles minimize noise and fuel use