The standard approach for measuring the flight path of an aircraft over a grid during drop test evaluations has been by visual means or by a GPS position from a device mounted in the plane. The flight path verification was used to document the aircraft flight path over the grid during the evaluation. The standalone GPS receivers operate at about 10m accuracy, and produce 1 or 2 readings while flying through the grid.
FPInnovations tested the use of a precision survey grade GPS operating in differential mode. The system was capable of 2 cm accuracy, and could produce approximately 100 measurements while flying through the grid. This gave the opportunity to see where the plane flew precisely, and also the ground speed and altitude of the drop. A precise vertical profile could be used in engineering flight analysis