“…Besides, several studies suggested that HRV could reflect pilots' mental workload and stress level (Alaimo et al, 2020; Cao et al, 2019; Goffeng et al, 2019; Mansikka et al, 2016), both of which were known contributors to in‐flight mental fatigue (Dai et al, 2020; Caldwell et al, 2009). From the device aspect, the fast‐developing unobtrusive ECG sensors, such as wristbands, armbands, chest straps, and embedded sensors (Kranjec et al, 2014; Rodrigues et al, 2018; Villani et al, 2020; N. Wilson et al, 2020), could replace traditional recorder systems which use contact ECG electrodes, thus further enhancing HRV's feasibility in real‐life conditions.…”