After a Very Large Array telescope has been serviced inside the Antenna Assembly Building, otherwise known as "the Barn," one of the two Transporters hauls it to the nearest pad, called the Master Pad, for testing. Here, the telescope receives data from the control room and can participate in observations as it is checked back into active service.

The Master Pad was the first pad constructed at the VLA and received the first VLA telescope in 1975.