I was under the impression that for non-surfaced subs the only way to communicate them was to fly close to the surface and lower a boom into the water. Is that not the case?
A “shot across the bows” is a colloquial expression for a warning demanding imminent action. The idea was that long ago if you couldn't communicate with some other ship, your last ditch effort to tell them to stop “or else” was to fire a cannonball over the nose (the bow) of the ship, so that you do not damage the ship but they would definitely see it and know you mean business.
So I imagine someone on this plane using the colloquial expression was just like “dammit! Follow us!! What more of a shot across the bows do you need?!” And someone else was like “you mean a literal one? I have some cable here, you drag that a few meters above the deck I bet it will make a terrible noise.” or something.
From what you’re explaining, the expression wasn’t something necessarily standardized “code yellow” sort of thing. Could two novices been able to convey or comprehend the meaning between themselves?
With stories like this, who needs film!
Maybe not for a towed line, though the shot across the bow is probably intuitive. That's essentially the same thing bees will do to warn you away from their hive.
The expression has somehow always felt more like a frontal attack that stops right before actually hitting you. But my head may have conflated it with "jemandem etwas vor den Latz knallen," which translates to "slap something in front of somebody's bib."
0. https://en.wikipedia.org/wiki/Lualualei_VLF_transmitter 1. https://twitter.com/lemonodor/status/1312134472280633345 2. https://twitter.com/thenewarea51/status/1347668162406477824