If you’ve ever had the opportunity to listen to the succinct communication between carrier operations and the aircraft in flight, it’s quite an experience. When a fighter jet is on approach and “in the groove” (i.e., 15-18 seconds to touchdown) to an aircraft carrier the Landing Signal Officer (LSO) onboard will say to the approaching aircraft, “Call the ball.”

He is asking for a couple of things, but primarily if the pilot can see the round orange "meatball" on the Optical Landing System (OLS). If he cannot see the ball for whatever reason, the pilot will transmit, “Clara.” This tells the LSO that the pilot is not receiving optical glide slope information, a situation that must be corrected by the pilot or LSO quickly. Otherwise, a wave-off is required, which equates to additional cost incurred in fuel, time, planning and even potential safety concerns.

Most all of the time though, the pilot will see the ball (and of course the related lighting system) and will note the orange ball's relation to the green horizontal datum lights. This will indicate if he is high, low, or on glide-slope.

In response to the LSO’s query to “Call the ball,” the pilot will answer by stating his side number, aircraft type, ‘ball,’ and fuel state (and qualification number if in training). It would most likely sound something like this:

Dallas two-two-one, Tomcat ball, five-point-seven.” This translates to: Dallas=VF-1's squadron call-sign, 221=the number on the side of the aircraft, Tomcat=F-14, ball=I see the ball, 5.7=5,700 pounds of fuel left.

Noting the information, the LSO would then respond, “Roger Ball.” The LSO would then only speak again if needed to correct some deviation… that in such a precision endeavor almost always happens.

https://www.airspacetechnologies.com/blog/call-the-ball-how-is-your-logistics-communication