Call sign confusion was identified as a major contributor to controller-pilot miscommunication incidents over 30 years ago. While strategies to mitigate this risk have been introduced, the issue of call sign confusion is still considered one of the biggest risks to civil aviation today, particularly as international civil air traffic continues to increase.

Despite the potential for call sign confusion to lead to severe consequences, research into the mechanisms behind why aviation professionals fail to recognize mistakes in radio transmissions is remarkably limited. The present research examined the serial positioning effects of primacy and recency on aircraft call signs, predicting that errors were more likely to be recognised if call signs were modified at either the designator or final digit.

Participants with aviation expertise were exposed to approximately 15 minutes of simulated air traffic ground radio transmissions. They were asked to keep a list of the call signs present in the task, and the number of times each call sign was heard. Half of the transmissions contained errors in call sign, occurring at the designator, or at one of the four digit positions within the call sign.

Tentative support was found for a serial positioning effect within aircraft calls signs. This indicated that if similar call signs differ in the middle, pilots and controllers are less likely detect the error. A stronger recency effect was found, implying that errors are most easily recognized if similar call signs differ in the final digit. Further the results suggest that the designator acts as a prefix, instead of part of the series itself.

If serial positioning affects the ability of pilots and controllers to recognise similar call signs, then the length and alphanumeric content of call signs should be carefully planned to minimise the opportunity for this confusion to arise.