Eurocontrol identifies loss of controller-pilot link and call-sign confusion as most likely to cause traffic conflicts
Loss of communication between pilots and controllers is the problem most likely to cause traffic conflicts about which controllers can do nothing, according to Eurocontrol research. But at a 30 September air-ground communications (AGC) workshop, Eurocontrol and representatives of all the stakeholders involved identified five different categories of problems involving AGC, and have agreed to develop remedial measures in time to implement an “early 2006” action plan designed to reduce or eliminate this source of risk.
In addition to “prolonged loss of communication” (PLC), the categories of AGC risk Eurocontrol has identified include call-sign confusion, undetected simultaneous transmissions, radio interference, and misunderstanding caused by non-standard phraseology.
Eurocontrol determined this by studying 535 occurrences of pilot/controller communications problems. The agency’s AGC safety expert Tzvetomir Blajev says: “Air/ground communications issues are among the key safety risk areas in air traffic management [ATM], and for this reason we need to redouble our efforts to address them urgently.”
Call-sign confusion by virtue of similar call signs was the cause of 175 of the 535 communications problems Eurocontrol investigated. For example the agency found that the word “air” is used as a prefix or suffix to a call sign in more than one in five radio-telephony designators worldwide, and if the rest of a flight’s call sign happens to be similar by virtue of sharing some letters or numerals with that of another flight in the same sector, the stage is set for potential misunderstanding.
This can be the use of the wrong call sign by the controller, or the wrong aircraft responding to a call intended for another that has a similar call sign. This, says Blajev, is a leading cause of “level-bust” events, in which the wrong aircraft is given – or reacts to – an instruction to change level.
DAVID LEARMOUNT/LONDON
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Incidents provoke military intercepts Europe-wide Eurocontrol’s air-ground communications safety expert Tzvetomir Blajev reveals that, prompted by prolonged loss of communication (PLC) incidents, there were more than 120 intercepts by military fighters of civil airliners over Europe during 2004. Loss of communication does not always result in conflict provided an aircraft sticks accurately to its flight plan and its last clearance, explains Blajev, but since 9/11 PLC has also become a security issue, hence the intercepts. Eurocontrol has found that there are 13 different causes for PLC incidents, the most common cause being “various technical issues” (23%), followed by frequency change (to the wrong frequency) either by incorrect selection (18%) or inadvertent action (8%). |
Source: Flight International
