Example:1944:20 000feet over Germany,a few hundred B17 s and escort fighters are attacked by say 50 Luftwaffe aircraft. Drop tanks are dropped,most aircraft miss their shots,expended ammo casings is raining down,aircraft are shot up etc. What happens?
In: Other
The drop tanks are dropped. They land where they land. Of course, WWII Europe was significantly rural, so low probability of tanks hitting anything significant.
For aircraft, what happened with casings were mixed. Some designs discarded them, others naturally collected in the aircraft ([common for bombers](https://www.pinterest.com/pin/258816309814058190/)).
They crash into the ground.
Usually for a warzone it’s one of the least dangerous things to fall out of the air that day.
IE it’s not literally a bomb or flaming burning plane wreckage.
Typically in peace time they don’t allow planes to drop their drop tanks. And they only shoot the guns in places designated to practice shooting.
There are claims that in [Vietnam they turned some drop tanks into canoes](https://www.flyingmag.com/pilots-places/pilots-adventures-more/unusual-river-boats-plying-vietnamese-waters/)
This is probably not the case, as the drop tank would likely be smashed from the long fall, probably they took some drop tanks from an abandoned storage place.
Just like any other expendable item during a war: they remain wherever they landed until picked up. Folks across Europe are still finding old guns, unexploded ordinance, etc across the continent. Same thing across Africa. You can bet at the DMZ they will NEVER recover every landmine there. These facts are some of the most horrifying facts of war. That years, even decades, after the conflict ends some will still be casualties.
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