When I'm not taking photos of airplanes, I make fleeting connections with truck drivers whizzing by. Sometimes, they blink the lights on their trucks, and I wave back at them. And when I see a particularly flashy truck, I wave to the driver first, and they usually reciprocate by flashing lights and honking. Maybe I'm reading too much into it, but there is something special in creating an ephemeral connection with someone, who happened to be at the same place and at the same time as you. I guess it's a tiny acknowledgement of each other's existence by signalling "I see you" and getting back "And I see you too!"
P. S. Today, I spotted a couple of trucks with bright LED crosses in their windshields. And yesterday, a waved back at a minivan from Denmark.