Hi all,
"within sight of air compressor"
As I remember, it must be within 3 feet of the device.
And usually the panel board will contain the air compressors "Primary Protection" rated at 125% of the FLA and the fused disconnect, "Secondary Protection" will be rated anywhere from 175% to 250% or higher per NEC 430 something depending on the fuse characteristics.
I'd like to add that using a MCCB as the primary protection with a fuse (in place of another MCCB) for the secondary protection offers the best combination of protection against both short circuit and arc flash serneros.