Originally Posted by BackPacker
I can imagine that being useful today. Throw the lead weight out and smell, taste, feel when it is brought back in. Wet - you must be over water. Covered in glass shards - you must be above an area with lots of greenhouses. Smelling of weed - you must have been above Amsterdam. Cleaner than when you threw it down - you must be over Switzerland. And so forth.
I wouldn't use it over Somalia - throw out lead weight, pause, almighty jerk on line, massive rate of descent, spend a couple of months waiting for insurers to negotiate release of crew and repatriation of airframe. Rookie mistake.