I have considered the possibility of GMP before. Someone else to pass airways and start-up clearance would take at least some of the pressure of the ADC. It may even be possible for GMP to be manned by an ATCA, provided they've had the appropriare R/T training as there would be no actual movement of aircraft governed on that frequency.
I have to say I'm not surprised Bristol GMC is seldom manned. It's often been said that Bristol and Leeds are two very similar airports (layout, lousy weather etc) and lack of GMC is another similarity ! Yet Bristol is a busier airport. I dare say the tower is equipped for GMC, it's just a case of having someone to occupy the seat. Same at LBA since the tower refit. Lovely new switch and console but nobody home

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I'm not familiar with a CA4114 report. Who gets to file these ? Is it ATC when they feel the pressure is on or is it aircrew ? I suppose the latter could file an ASR if they experience serious frequency congestion.
It's Thursday so I'll have to listen at lunchtime and see what goes on. Thankyou for your replies everybody.