Shift work and workload: effects on air traffic controllers communications

It is well established that organizational and environmental factors such as shift work and workload influence cognitive performance level. Despite this, the extent to which work shifts and workload influence air traffic controllers communication is still unclear. This might represent a critical area, as it is suggested by the fact that communicative failures are implied in more than 70% of incidents and accidents in air navigation. We investigated the extent to which the structure of controllers communications varied relative to work shifts (morning, afternoon, night) and workload level. In particular, we focused on referential ambiguity, deviations from standard phraseology and possible misunderstandings. Our study was based on 10 hours transcribed radio communications between tower and radar controllers and pilots in an Italian airport. The results showed that despite the fact that controllers and pilots should communicate in English by means of a highly formalized phraseology, they instead employed a nonstandard code characterized by many deviations from standard phraseology (use of Italian and of non-standard expressions, ellipses, redundancies). Communicative patterns and accuracy were significantly different according to shifts and workload: while communicative deviations increased during the nightshift and with a low workload, the best performance was found in the morning shift