Banner-toting airplanes, though sometimes loud, are usually not heavy on commentary; they are better known as a flashy way to propose marriage or promote happy hour at a local bar.

And protests, more often than not, take to the streets rather than to the skies.

Recently, however, the two have converged. Starting in December and continuing through last week, five banners blaring criticism of the mayor and support for police officers have been towed over the Hudson River. That followed several banners sent airborne over New Jersey by New York Jets fans pleading with the team’s owner to fire John Idzik, the team’s general manager.

In an era of microtargeted digital ads that can reach millions of carefully chosen eyeballs, the idea of paying a gas-guzzling aircraft to tow a few words for a short window of time might seem antiquated. But those who have recently done it said it was a way to send a conspicuous message that drew widespread news coverage. It was also relatively inexpensive, especially when multiple people shared the cost, as was the case with both sets of banners.

A group of retired police officers, calling themselves Retired N.Y.P.D. for a Safe New York, have claimed responsibility for the last three of the anti-de Blasio banners. Their leader, who identified himself only as Captain Dave, said he was an officer for 21 years. He requested anonymity for privacy reasons, he said, not because he feared retaliation from the mayor’s office.