Airplane symbol on highway?

It is a marker used to time a cars rate of speed for enforcement of speed laws.

Airplane Highways

Two right and one wrong. In OK there are large yellow circles, mostly on interstate highways. On regular roads, the 'bear in the air' times the vehicle between landmarks. I am not really sure about the part about relaying the message to the officer on the ground and them writing the citation. In OK the officer observing the infraction must sign the citation, but the officer on the ground will issue a warning ticket.

Several states in the USA use airplanes to observe and time cars speeding on the highway. There is a measured distance between two airplane symbols painted on the side of the roadway, and the pilot can time a car as it passes from one mark to the next and calculate the cars speed. If the car is going over the posted speed limit, the pilot relays that info to a patrol car on the ground, and they can stop the speeder and issue a citation.

it means that that particular stretch of road can be used as an emergency landing strip