Collisions on the ground and in the air have been caused by communications breakdown. It simply should not happen
Voice communication is so basic to the function of air traffic control that those who use it routinely without encountering problems can easily forget how critical it is.
Witnessing a loss of communication between a controller and at least one aircraft – especially in a terminal area or any other busy, complex sector – is the most dramatic reminder of just how critical it can be. Even if it does not end in grief, it creates a lot of stress.
But actual loss of air/ground communication  is only one of the forms that a communications problem can take. Eurocontrol has just completed its initial analysis of 535 reported incidents and it reveals – in fascinating detail – just how complex this most fundamental of all communications tools is, and what a large number of hazards can result from all the possible combinations of malfunctions, mistakes and misunderstandings.
When, about five years ago, Eurocontrol began to push hard for a better reporting system for ATC incidents – and more encouragement for individuals involved to file reports – it was hoping to gather this kind of data; the kind that would enable it to gauge the size, frequency and nature of particular problems, and thus determine how to overcome them. Knowledge like this also enables the agency to determine whether a problem is more or less serious than commonly believed. Eurocontrol’s early analysis of its communications study indicates that breakdowns are a hazard that has to be taken more seriously than it now is. Communications failures/mistakes may not be the only cause of runway incursion or level-bust incidents, but frequently such potential – or actual – disasters were precipitated by communications factors like misunderstanding or call-sign confusion.
Now the agency has to work out an action plan to deal with all the primary causes and secondary effects of communications breakdown.
One tool, at present used only by a small percentage of operators in Europe, could go a long way to eliminating many of the problems associated with voice communications – controller/pilot datalink communications (CPDLC). Eurocontrol has a well-established programme – Link 2000+ – for the introduction of VHF datalink (VDL) for ATC purposes including CPDLC. One of the outcomes of the agency’s communications action plan may well be a recommendation to accelerate the CPDLC programme, encouraging airlines to fit VDL-2 equipment earlier than they might otherwise have done.  At a stroke, CPDLC has the capability to reduce the risks associated with a range of events, including, to name but a few: call-sign confusion; misunderstanding resulting from non-standard language, interference or simultaneous transmission; loss of communication caused by stuck transmit switches; pilot selection of the wrong frequency, and numerous other common voice communication problems.
In addition, in the event of prolonged loss of voice communication, whether caused by equipment failure, incorrect frequency selection or any other cause, CPDLC provides an independent channel through which to establish communication. Meanwhile, the sky is less filled with chatter because routine communications are uplinked and acknowledgement downlinked, taking the pressure off the airwaves.
But until the necessary VDL-2 air and ground equipment is supplied and pilots and controllers have been fully trained in its use, Eurocontrol clearly does not intend to sit on its hands and pray a communications incident does not become an accident. So what can the agency do? By early next year the industry has been promised an action plan.
Meanwhile, industry should use Eurocontrol’s raw data to apply some commonsense measures. For a start, remind crews that they should be monitoring the emergency frequency 121.5MHz on their third “box” – are there really so many airlines out there that do not have triple serviceable VHF radios on their flightdecks? Apparently many pilots do not monitor 121.5, which ATC uses when other methods of contacting an aircraft they have “lost” have failed.
But just spreading general awareness that communications break down more often than pilots realise – frequently because of sloppiness in language or radio telephony discipline – could make the skies much safer at no cost to anyone.  

Source: Flight International