Use this calculator for flight-planning study or a first-pass cross-check when all inputs describe the same aircraft, atmospheric condition, and phase of flight.

Current altitude (ft)

Current cruise altitude.

Target altitude (ft)

Target altitude at the point of arrival.

Descent rate (ft/min)

Planned vertical speed during the descent.

Ground speed (kt)

Ground speed during the descent.

Compute the distance before the target where a descent must begin for a given rate and ground speed. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Top of descent (nm)

Distance before the target at which the descent should start.

• Do not use a generic calculator in place of the current aircraft flight manual, approved performance data, operating limitations, NOTAMs, weather, or regulations. Real performance changes with configuration, runway condition, altitude, temperature, wind, loading, and technique.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check the result against the aircraft flight manual or approved planning system, then apply the required safety margins. Keep signed wind, heading, altitude, speed, and fuel conventions explicit.

• Descent Rate Calculator

  Compute the vertical speed needed to hold a descent angle at a given ground speed.

• Estimated Trip Fuel Calculator

  Estimate the fuel needed for a trip from distance, ground speed, and fuel burn rate.

• Flight Time Calculator

  Compute the flight time over a distance at a given ground speed.