I've spent most of my life in places with lots of airborne activity to notice and watch. I grew up near a major Air Force base. We heard sonic booms every day on the school playground and learned how far to "lead" the sound's origin when looking at the sky, so as to spot the jet traveling much faster than its sound. The base was also a center for B-52 operations. During the Vietnam War years, I'd see news footage of the unmistakable "Stratofortress" silhouette over a jungle and think, Yes, that's just how it looked over our house.
Except for the three weeks after September 11, 2001. the skies over downtown Washington are constantly full of planes coming down the river for landings at National Airport and helicopters buzzing around. (Even during those three weeks, a constant high whine came at night from fighter jets patrolling overhead.) Seattle has heavy traffic in and out of Sea-Tac and Boeing Field, plus sea planes flying low to and from their base on Lake Union. Similarly in San Francisco and elsewhere. Like every other person I've met who enjoys flying airplanes, I look up the instant I hear a small plane to see what kind it is. Most places in America, there is a lot to watch.
Not so in Shanghai. Apart from the occasional kite and, of course, the usual particulates, the skies are empty most of the time. One of the city's airports -- the big, new one, Pudong - is very far away from downtown. The older, closer one, Hongqiao, has traffic patterns that avoid the center of the city. Once I saw a blimp, and once or twice I've seen a helicopter. As mentioned earlier, there are not even many birds to catch the eye.
But today: Fighter planes! It sounded like several, rather than just one, swooping in relatively low circles over the northeastern Hankou district around 2pm. Because they were moving in and out of clouds, I couldn't tell exactly what kind they were. But they definitely were military fighters, and they appeared just to be flying around rather than putting on air show. A courtesy visit, or ceremonial appearance? There was nothing in the papers about it. For some reason a display of strength? A flight for no apparent reason, by an air force unit that happened to be nearby? I'll add this to the list of events I hope some day to understand.