Random, I haven't read back to check where we may have got crossed wires but dropping from height is certainly an issue.
In a light wind, say 36kts, the sonobuoy will drift at 20 yards per second. At 20,000ft, free fall the time in air will be in the order of 40 seconds and 800 yards drift. Add a rotor and halve the drop rate and you are near 1 nm adrift. Finding all your buoys post drop become essential - a GPS transmitter would fix that.
Indeed a bit like the old smoke float, drop one and calculate the wind. I wonder why we never did that?