How to calculate the SORA operational volume

• Flight geography — where you intend to fly, drawn by you: the area and the height band (H_FG) of the planned operation.
• Contingency volume — a margin around it (lateral S_CV, vertical H_CV) that absorbs navigation error, your reaction time and the manoeuvre that stops the aircraft once it leaves the flight geography.
• Ground risk buffer — ground beyond the contingency volume (S_GRB) where the aircraft could land after a flight termination, which must be treated as part of the overflown area.

Together the flight geography and contingency volume form the operational volume. The method also defines an adjacent volume around it — two minutes of flight at V0 laterally, and 150 m above — used for the air risk assessment.

V0 is the maximum operating speed, CD the characteristic dimension, t the reaction time and g = 9.81 m/s². For a multirotor that stops by pitching (θ) and a ground risk buffer by the 1:1 rule or a ballistic fall:

S_CV = S_GPS + S_Pos + S_K + S_RZ + S_CM
S_RZ = V0 × t
S_CM (multirotor stop) = ½ V0² / (g × tan θ)
H_CV = H_FG + H_baro + H_RZ + H_CM
H_RZ = 0.7 × V0 × t
H_CM (multirotor) = ½ V0² / g
S_GRB (1:1 rule) = H_CV + ½ CD
S_GRB (ballistic) = V0 × √(2 H_CV / g) + ½ CD

H_baro is 1 m with barometric height and 4 m with GNSS height. Fixed-wing aircraft use a turn radius (V0² / (g × tan φ)) instead of a stop, and a parachute termination replaces the manoeuvre with the distance flown while the canopy opens.

The method publishes defaults for the terms you may not have measured. You can override any of them, but the override must be justified to your authority:

A multirotor flying at up to V0 = 10 m/s, with CD = 0.5 m, a flight geography up to 120 m, barometric height and every other term at its default:

The choice of ground-risk-buffer method matters more than any other input here: the ballistic calculation gives a buffer less than half the size of the 1:1 rule, but you must be able to justify that the aircraft actually falls ballistically when terminated.

The GeoPilot SORA calculator applies this method to your own inputs and shows every term with where it came from — your input, a method constant or a calculation — so your application can carry the derivation. It dimensions the volumes; it does not produce the GRC, ARC or SAIL of a full SORA.

These figures are an aid to preparing an application, not an authorization or a regulatory approval. Every value must be verified and justified by the operator to the competent authority.