Study sheds light on the role of language background in miscommunication between pilots and air traffic controllers

English is the language used around the world by civil aviation professionals, including pilots, flight dispatchers, and air traffic controllers. New research suggests that words — as opposed to numbers — are a more frequent source of errors among pilots with English as a second language.

The findings appear in The International Journal of Aerospace Psychology.

For their study, the researchers analyzed and systematically coded 18 hours of communications from Tower, Approach and Departure frequencies at Kingsford Smith International Airport in Sydney, Australia. They ended up with 132 “accented English” and 141 “native English sounding” pilot transmissions.

Pilots are required to read back instructions from air traffic controllers to confirm they heard them correctly. The researchers were interested in two types of errors — omissions in the readback, and readbacks that included the wrong information.

Both native English speakers and accented pilots omitted a similar number of items per transmission on average. The item most commonly omitted in readbacks from native English pilots was their runway assignment, while for accented pilots it was both altitude and runway assignment.

None of the readbacks from native English speakers included inaccurate information. But that was not the case for accented pilots.

“The fact that both groups of pilots make errors in their transmissions highlights the ongoing challenge of effective communication in aviation. For native English sounding pilots, since they committed omissions rather than mistakes, the challenges seem to be those of remembering (or learning and recalling) what items must be read back, or adhering to the protocol,” the researchers said.

“For [English as a second language] pilots, who committed both omissions and mistakes, the challenges seem to involve both remembering which items must be read back and ensuring accurate readback.”

The researchers also found that the error rate increased as the number of items in the transmission increased — but only for accented pilots. They were surprised to find that the phase of flight appeared to have no effect on the rate communication errors.

Overall, there was no significant difference between native English pilots and accented pilots in regards to numerical errors. But accent pilots committed significantly more word errors per transmission than native English pilots.

“This new finding has important implications for aviation communication training. The choice of lexical items in aviation is constrained by the phraseology, in contrast to numbers where the possible range is very large. Knowing that improvements in aviation communication can be obtained by improving pilots’ mastery of the phraseology allows for a targeted approach,” the authors of the study noted.

The study, “An Investigation into the Factors that Affect Miscommunication between Pilots and Air Traffic Controllers in Commercial Aviation“, was authored by Qiong Wu, Brett R. C. Molesworth, and Dominique Estival.