Development and validation of an assessment index for quantifying cognitive task load in pilots under simulated flight conditions using heart rate variability and principal component analysis

Abstract

To investigate whether high cognitive task load (CTL) for aircraft pilots can be identified by analysing heart-rate variability, electrocardiograms were recorded while cadet pilots (n = 68) performed the plane tracking, anti-gravity pedalling, and reaction tasks during simulated flight missions. Data for standard electrocardiogram parameters were extracted from the R–R-interval series. In the research phase, low frequency power (LF), high frequency power (HF), normalised HF, and LF/HF differed significantly between high and low CTL conditions (p < .05 for all). A principal component analysis identified three components contributing 90.62% of cumulative heart-rate variance. These principal components were incorporated into a composite index. Validation in a separate group of cadet pilots (n = 139) under similar conditions showed that the index value significantly increased with increasing CTL (p < .05). The heart-rate variability index can be used to objectively identify high CTL flight conditions.

Practitioner summary: We used principal component analysis of electrocardiogram data to construct a composite index for identifying high cognitive task load in pilots during simulated flight. We validated the index in a separate group of pilots under similar conditions. The index can be used to improve cadet training and flight safety.

Abbreviations: ANOVA: a one-way analysis of variance; AP: anti-gravity pedaling task; CTL: cognitive task load; ECG: electrocardiograms; HR: heart rate; HRV: heart-rate variability; HRVI: heart-rate variability index; PT: plane-tracking task; RMSSD: root-mean square of differences between consecutive R–R intervals; RT: reaction task; SDNN: standard deviation of R-R intervals; HF: high frequency power; HFnu: normalized HF; LF: low frequency power; LFnu: normalized LF; PCA: principal component analysis.

Keywords:

• Aircraft pilot
• cognitive task load
• electrocardiogram
• flight simulator
• heart rate variability

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data set cannot be made publicly available due to participant confidentiality. Data will be shared with researchers who provide a methodologically and ethically sound proposal for their study. Requests should be directed to the corresponding authors. All requests will require a data access agreement.

Additional information

Funding

This study was supported by the Key Program of National Natural Science Foundation of China [grant number: U1933201], National Natural Science Foundation of China [grant number: 72101262] and Key R&D Program of Shaanxi Province [grant number: 2022SF-114, 2022SF-101]. The funders had no role in its design, data collection, data analysis, data interpretation, or the writing of the report.