At a particular instant, a stationary observer on the ground sees a package falling with a speed ${\mathrm{v}}_1$ at an angle $\mathrm{\theta }$ to the vertical. To a pilot flying horizontally with a constant speed $\mathrm{v}$ relative to the ground, the package appears to be falling vertically with a speed ${\mathrm{v}}_2$ ( at that same instant ). The speed of the pilot relative to the ground $\left(\mathrm{v}\right)$ is