Top of Descent Calculator

Calculate when to begin descent for a comfortable approach.

Pattern altitude or IAF altitude

Quick Rules of Thumb

  • 3 degree glide: ~3 nm per 1,000 ft to lose
  • Descent rate for 3 deg: GS x 5 (e.g., 120 kt = 600 fpm)
  • Quick TOD: (Alt to lose / 1000) x 3 = nm

Descent Rate Reference

Ground Speed3 Deg Rate
90 kt475 fpm
120 kt635 fpm
150 kt795 fpm
180 kt955 fpm