BACKGROUND: Mental fatigue and sleepiness are well recognized determinants of human-error related accidents and incidents in aviation. In Brazil, according to the Center for Investigation and Prevention of Aeronautical Accidents (CENIPA), the rate of accidents in the aerial modal is 1 per 2 d. Human factors are present in 90% of these accidents.CASE REPORT: This paper describes a retrospective study of the communication between a pilot and an air traffic control tower just before a fatal accident. The objective was the detection of fatigue and sleepiness of a pilot, who complained of these signs and symptoms before the flight, by means of voice and speech analysis. The in-depth accident analysis performed by CENIPA indicated that sleepiness and fatigue most likely contributed to the accident. Speech samples were analyzed for two conditions: 1) nonsleepy data recorded 35 h before the air crash (control condition), which were compared with 2) data from samples collected about 1 h before the accident and also during the disaster (sleepy condition). Audio recording analyses provided objective measures of the temporal organization of speech, such as hesitations, silent pauses, prolongation of final syllables, and syllable articulation rate.DISCUSSION: The results showed that speech during the day of the accident had significantly low elocution and articulation rates compared to the preceding day, also indicating that the methodology adopted in this study is feasible for detection of fatigue and sleepiness through speech analysis.de Vasconcelos CA, Vieira MN, Kecklund G, Yehia HC. Speech analysis for fatigue and sleepiness detection of a pilot. Aerosp Med Hum Perform. 2019; 90(4):415-418.