Assessment of fatigue in personnel during sustained operations using ‘SOAP’ – Sustained Operational Assessment Profile

Subjects

A total of 1521 aircrew and ground crew at various IAF stations completed the SOAP questionnaires during the first phase of the study. In the second phase, 140 aircrew participated in the study.

Experimental protocol

SOAP profile was completed twice during the simulated sustained military operation on two phases. In the first phase, the sustain operation was for 8 days, and in the second phase, it was for 6 days. In the first phase, the SOAP questionnaire was filled up after 48 h of commencement of the exercise and once again at the end of 5 days of sustained operation. In the second phase, to ascertain differences in the subjective ratings of SOAP among different streams of pilots, data were recorded during another simulated sustained operation carried out after 6 months of initial exercise. In this phase, a total of 140 aircrew responded to the SOAP questionnaire during 6 days of sustained operations. SOAP score was acquired on day 1 and day 6 of the operations. The subjects were asked to rate their subjective responses on a scale of 1–5 to obtain subjective measures of concentration, boredom, slowed reactions, anxiety, depression, irritability, fatigue, poor sleep, work frustration, and physical discomfort.

Statistical analysis

The data were analyzed using non-parametric statistical methods, Wilcoxon matched paired test. The two levels of repeated measures being mean SOAP scores on day 2 and that on day 5. The significance level was kept at P < 0.05.

Effect of sustained operation

The statistically significant differences in the subjective SOAP ratings of day 2 and day 5 of the simulated sustained operations signify cumulative effects on cognition, affect, and arousal of the personnel involved in these operations.^[1] The confounding effects of other stressors on the subjective ratings have been ruled out in the study. The prime adverse environmental factor in India is heat stress. Heat stress during sustained operations may have similar effects on the dimensions of SOAP ratings.^[1-4] Since the experimentation was carried out in the month of November, which is a thermally comfortable weather period in India, heat stress due to weather can be confidently discounted for confounding the findings of the study.

The simulated sustained operations continued for 8 days, which included the continuous operational deployment of various complements of the fleet. The detailed information of the operations, being restricted, has not been described in the results. However, it is worth mentioning that all personnel were detailed for their qualification specific duties. During sustained operations, the tradesmen and aircrew commenced “shift work” whenever operationally feasible. However, it cannot be denied that due to operational necessities, some of the tradesmen would have been detailed to work beyond their normal tour of duty.

During the sustained operations, to ensure maximum availability of “flying fit” aircrew, only non-pharmacological measures for fatigue and alertness management such as good sleep hygiene and adequate sleep/rest before the mission and scientific rostering of aircrew for flying^[2] were employed. “Adequate rest” was ensured for the aircrew as per the extant flying orders, including “flight duty time limitation” (FDTL). In addition, the well-known “strategic cockpit napping” (in transport aircraft and dual cockpit fighter aircraft) and activity breaks^[5-7] were prescribed and practiced by the aircrew. The flying missions during the sustained operations period were short-haul missions; therefore, fatigue, tiredness, or boredom inherent to long-haul or ultra-long-haul flying sorties were not present.^[7,8] None of the units resorted to pharmacological fatigue management, i.e., use of Go and NoGo pills (modafinil and zolpidem, respectively).

In the study, mean response scores of all the personnel (n = 1521) over 5 days of sustained operations indicated accumulated, statistically significant, increase in all dimensions of SOAP, namely, cognition, affect, and arousal.^[1]

Beneficial effect of shift work

On fine-grained analysis of SOAP scores, over 5 days of sustained operations among the personnel of different trades/ branches, it was revealed that the personnel from trades such as Air Traffic Controllers and Aircraft Maintenance Crew, the SOAP rating scores were not significantly increased. This statistically backed finding can be explained by the routine working philosophy of these branches of IAF, wherein the personnel of these trades are routinely involved in “shift work.” Hence, the sustained operations and continuous manning did not result in statistically significant changes in any of the dimensions of SOAP. On the contrary, the Administrative Support Group, Flying Branch, and Air Defense revealed a statistically significant increase in SOAP ratings. Once again, the answer lies in the working philosophy of these branches in IAF. These branches do not routinely follow a “shift work” culture; hence, sustained operations have resulted in statistically significant adverse effects on cognition, affect, and arousal of the personnel.^[2] There is enough literature available to support that circadian disruption (that happens when individuals initially break into “shift” work) is a major cause of aircrew fatigue.^[9-11]

Although, personnel from trades such as Air Traffic Controllers and Aircraft Maintenance Crew who did not reveal statistically significant differences in the cardinal dimensions of SOAP scores, there were significant changes in certain SOAP scales, namely, poor concentration, irritability, work frustration, fatigue, and poor sleep, which are reasonable due to the perceived or actual work pressure during such operations and long working hours.

Fine-grained analysis of pilots’ ratings

All aircrew (all pilots, flight engineers, flight gunners, etc.) showed significantly higher subjective response after 5 days of sustained operations in all the 10 SOAP scales. To further understand this observation, aircrew from various streams (namely, fighter, transport, and helicopter) responded to the SOAP questionnaire during subsequent simulated sustained operations exercise organized after 6 months of the original study. In this study, 140 aircrew from all the three streams responded to the 90 sustained operations profile questions over 6 days of sustained operations. The analysis revealed that the pilots from transport and helicopter stream did not show statistically significant differences in any of the SOAP scales, whereas fighter pilots experienced a statistically significant increase in their SOAP scores. The possible explanation of this observation finds basis in the basic differences in the operational tasking of various streams of aircraft. The transport and helicopter aircrew are routinely involved in long working hours with multiple takeoffs and landings; therefore, these aircrew may be better adapted to long working hours and sustained operations as compared to fighter aircrew.