Evening ATC operations question!
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Just out of interest, could it ever happen that while the said controller was giving departure instructions on the Tower frequency, a May Day call was being transmitted on the Radar frequency but not heard as the controller was busy on another channel?
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Just out of interest, could it ever happen that while the said controller was giving departure instructions on the Tower frequency, a May Day call was being transmitted on the Radar frequency but not heard as the controller was busy on another channel?
The modern VCCS (Voice Communication Control Systems) that most ATC units use allow the controllers to "couple" two or more frequencies together. This means they then act as if they were the same frequency. So if Radar and Tower were coupled, an aircraft on the radar frequency would hear all tower transmissions and vice versa.
It could happen that a controller was giving a departure clearance whilst an aircraft on the radar frequency was wanting to make a MAYDAY, but the pilot would hear the tower transmissions and have to wait for an appropriate gap to transmit his MAYDAY. No different to if someone on the radar frequency needed to declare a MAYDAY whilst a controller was giving turn/descent instructions to any other aircraft.
BigDaddyBoxMeal
Are you sure the VCCS is actually cross-coupling the frequencies, ie a call received on one freq is automatically re-transmitted by ATC on the other?
From what I hear (or don't hear!) from a nearby ANSP who operates TWR/APS they have operate with a cross-coupling system. Echoing the sentiment expressed by Hotel Tango, wonder if the relevant hazard appeared in the risk assessments? If cross-coupling is not mandated I would speculate that there would have to be some quite innovative mitigation developed to get the risk down to ALARP!
Haven't yet met a cross-coupling system that effectively does it. If you know of one I'd appreciate a PM.
Are you sure the VCCS is actually cross-coupling the frequencies, ie a call received on one freq is automatically re-transmitted by ATC on the other?
From what I hear (or don't hear!) from a nearby ANSP who operates TWR/APS they have operate with a cross-coupling system. Echoing the sentiment expressed by Hotel Tango, wonder if the relevant hazard appeared in the risk assessments? If cross-coupling is not mandated I would speculate that there would have to be some quite innovative mitigation developed to get the risk down to ALARP!
Haven't yet met a cross-coupling system that effectively does it. If you know of one I'd appreciate a PM.
The VCCS at Farnborough does a good job of cross coupling; I've operated 125.250/134.350 coupled, 123.225/132.8 coupled and 122.5/vehicle UHF coupled with no problems.
I would assume that a proven cross coupling VCCS is a CAA requirement before they allow you to 'trial' its operational use for combined ADI/APS.
I would assume that a proven cross coupling VCCS is a CAA requirement before they allow you to 'trial' its operational use for combined ADI/APS.
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Your Schmid VCCS can cross couple frequencies in different configurations depending on how the ATCO has selected the frequencies... So yes both aircraft will here the ATCO's Tx however if the aircraft are on different frequencies (TWR/APP) they won't hear each other.
As a tels man, the Schmid switch is the best in my opinion but they are all required by the CAA to conform to CAP670
As a tels man, the Schmid switch is the best in my opinion but they are all required by the CAA to conform to CAP670
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I don't see real risk in combining the two, less then with the RTO (Remote Tower Operations) approach, in test since 2011 (Releasing remote towers | SESAR). Does anybody have news on the status of RTO plans? At least the Saab product is approved (http://www.saabgroup.com/Civil-secur...ote-Tower-Pre/) and ready to buying.
