Spotlight on research and development (R&D)

Research on stress caused by administrative hassles, physical challenges, and the emotional trauma of war aims to lessen its negative effects and improve the psychological health of flight crews.

By Krista Ratwani, PhD

Welcome to the Spotlight on R&D column! This column showcases research activities and projects underway in many of the R&D Laboratories within the U.S. Department of Defense, partnering organizations, and the academic and practitioner community in military psychology. Research featured in the column includes a wide variety of studies and programs, ranging from preliminary findings on single studies to more substantive summaries of programmatic efforts on targeted research topics. Research described in the column is inclusive of all disciplines relevant to military psychology—spanning the entire spectrum of psychology, including clinical and experimental as well as basic and applied. If you would like your work to be showcased in this column, please contact Krista Ratwani via email or at 202-552-6127.

This edition of the newsletter highlights work conducted to understand the types of stressors faced by aircrew members. Specifically, the relationship between three types of stressors (administrative flight, physical and war) was examined in relation to four stress responses (posttraumatic stress disorder [PTSD], depression, sleepiness, and nervousness) related to flying. The research described here has important implications for examining how stressors may impact performance.

The role of in-flight administrative, physical and war stressors in aircrew psychological stress: a preliminary look

Thomas A. Stetz, PhD, and LTC Melba C. Stetz, PhD
Hawaii Pacific University, Honolulu

Research overview

The U.S. military is heavily dependent on helicopters for supporting ground forces in combat as well as to move troops and equipment by air. Nevertheless, behavioral health subject matter experts have noted a dearth of mental health resources deployed within aviation brigades (Mental Health Advisory Team V, 2008). Other than keeping crew members well-rested and alert (e.g., via caffeinated products), efforts to help aviators and crew members deal with flight stressors are limited. Therefore, researchers could greatly help the operational community by identifying the most significant types of flight stressors and then developing ways to keep aircrews at optimal psycho-physiological levels during deployments.

Factors such as sleep and the cognitive and physical demands of flying and their relationship with flight performance have been popular research topics within the human factors and aviation community. There has been much less research, however, on the psychological health of flight crews from an occupational stress approach. Within that approach, a stressor can be defined as anything external (Breznitz & Goldberger, 1993) or internal that causes either psychologically or physiologically stress (e.g., tension, discomfort; see McEwen & Mendelson, 1993). Thus, there is little to no research that examines the more mundane aspects of flying as an occupation, such as operational planning, administrative hassles, and their importance in stressor–stress relationships. In addition, the effect of commonly encountered war stressors, such as seeing dead bodies or knowing someone who has been killed, on aircrews is unknown. The present research aims to fill this void.

Solution and approach

This research examined three types of stressors (administrative flight, physical, and war) and their relationship with four stress responses (depression, sleepiness, PTSD, and nervousness). The variables are further explained below in the Measures section. Even though the intent of this study was not to identify the common stressors for all aviators, knowing each stressor’s relative importance in the prediction of stress should aid in identifying interventions that can ameliorate immediate stress responses.

To test the stressor–stress relationships, members (n = 272) of aviation team (e.g., tactical and medical evacuation) units were surveyed. Only in-aircraft personnel were included in the analysis. That is, no ground or supports on land members were included. Pilots composed the largest portion of respondents (n = 101; 37 percent). Other groups of respondents were crew chief/repairer (n = 91; 33 percent), medic (n = 22; 8 percent), door gunner (n = 9; 3 percent), and other/unspecified (n = 49; 18 percent). The age of the respondents was measured as using a categorical variable: 23 percent were under 25 years of age (n = 60), 54 percent were between 25 and 34 years of age (n = 147), 21 percent were 35 years of age or older (n = 58), and 3 percent (n = 7) were unspecified. Finally, 94 percent (n = 256) were male, 3 percent were female (n = 7), and 3 percent (n = 9) did not declare their gender.


The questionnaire for this study was composed of both extensively used measures and new, locally created items to explore previously unresearched areas.

Stressors. First, three new stressor measures were developed for this study to assess administrative flight stressors, physical stressors, and war stressors. 

1. Administrative flight stressors. An experienced Army research psychologist and an experienced combat pilot developed several statements that assessed the administrative flight stressors associated with flying. A standard lead-in question was used: “Since you started your present deployment, how much are the following things bothering you?” The four administrative aspects of combat flying assessed were “mission planning,” “flight profiles,” “admin (noncombat) flights,” and “nonstandard missions.” Each question was rated on a 5-point scale ranging from 0 (not at all) to 4 (extremely). The sum of the questions was taken as the measure of flying stressors. The measure demonstrated good internal consistency (a = .71).

2. Physical stressors. The same question stem as with the administrative flight stressors was used to assess the physical stressors. The following four physical aspects were assessed: “seats in aircraft,” “noise in the aircraft,” “equipment in the aircraft,” and “equipment on your body.” Each question was rated on the same 5-point scale as the administrative flight stressors, with the sum of the responses representing the measure of physical stressors. Internal consistency for this scale was also good (a = .86).

3. War stressors. The third stressor measure developed for this study assessed war stressors and asked the respondent if he or she experienced five different events since being deployed: “artillery, rocket, or mortar fire”; “know someone killed or injured”; “saw destroyed homes”; “saw dead bodies”; and “working in mined or areas with IEDs [improvised explosive devices].” Those five items could be perceived by a reasonable person to generate stress responses in most individuals. Each item was rated on a Yes/No scale, with “No” being scored as 0, and “Yes” being scored as 1. Cronbach’s alpha for these items was .71.

Stress responses/outcomes. Four stress outcomes were measured in this study (PTSD, depression, sleepiness, and nervousness related to flying). Three out of the four scales used were highly validated through past research, and the fourth was created.

1. Posttraumatic Stress Disorder Checklist (PCL-M). First, the PCL-M (Weathers, Huska, & Keane, 1991), a measure specifically designed for military experiences, was used. The question stem is “In the past month, how much have you been bothered by ...” and then is followed by 17 items that correspond to the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM–IV; American Psychiatric Association, 1994) symptoms of PTSD (e.g., “Repeated, disturbing memories, thoughts, or images of a stressful military experience” and “Feeling very upset when something reminded you of a stressful military experience”). It is a highly used and validated measure of PTSD (Bliese et al., 2008; Weathers, Litz, Herman, Huska, & Keane, 1993). The items were rated on a 5-point scale ranging from 1 (not at all) to 5 (extremely), and the internal consistency was .95.

2. Patient Health Questionnaire–9 (PHQ-9). The PHQ-9 (Kroenke & Spitzer, 2002; Kroenke, Spitzer, & Williams, 2009) is a nine-item depression scale that has been extensively used and has been shown to be a reliable and valid measure of depression. Respondents were asked, “Over the past two weeks, how often have you been bothered by any of the following problems?” The listed problems were based directly on the diagnostic criteria for major depressive disorder in the DSM–IV (e.g., “Feeling down, depressed, or hopeless”). The internal consistency for this measure was good (a = .89).

3. Epworth Sleepiness Scale. The Epworth Sleepiness Scale (Johns, 1991, 1998) is an extensively used measure of daytime sleepiness. A single question lead asks how likely the respondent is to doze off or fall asleep in eight different situations, such as watching TV, lying down in the afternoon, and sitting and talking to someone. The scale uses a 4-point scale ranging from 0 (no chance of dozing) to 3 (high chance of dozing). Cronbach’s alpha for the scale in this study was .81.

4. Nervousness. Finally, three newly created items were designed to measure Nervousness related to flying. The lead question asked, “Since you started your present deployment, how much are the following things bothering you?”—which was followed by “nervousness before flying,” “nervousness during the flight,” and “nervousness after the flight.” Each question was rated on a 5-point scale ranging from 0 (not at all) to 4 (extremely), and the internal consistency was good (a = .82).


To determine the relative contribution of each stressor in the prediction of stress responses, four regression analyses were conducted. The results of those analyses are displayed in Table 1. Examination of Table 1 shows that, as a group, the stressors (Administrative Flight Stressors, Physical Stressors, and War Stressors) played a significant role in the prediction of the four examined stress responses (nervousness related to flying, sleepiness, depression, and PTSD). The R2 values ranged from .26 to .51, indicating that the stressors explained between 26 percent and 51 percent of the variance in the stress responses.

Interestingly, administrative flight stressors played the most important role in the prediction of stress in each analysis, as indicated by the large and significant beta weights. The second most important stressor was physical stressors. In each analysis, that stressor was statistically significant and also had the second largest beta weight. Finally, war stressors occasionally played a significant role in the prediction of stress; it was statistically significant in the prediction of nervousness related to flying and PTSD, but not in the other two stress responses (sleepiness and depression).


This study shines light on an underresearched area in the field of aviation psychology. A great deal of research has focused on in-flight stressors and their association with flight performance. However, much less research has focused on psychological health stress/outcomes such as sleepiness, depression, PTSD, and nervousness or the administrative hassles and stressors associated with flying or with war stressors.

Results demonstrate that both physical and administrative flight stressors associated with flying are important factors in the prediction of sleepiness, depression, PTSD, and nervousness. As physical and administrative flight Stressors increased, the stress responses worsened. It was also shown that War Stressors were an important factor in predicting nervousness and PTSD, indicating that increased War Stressors are positively associated with those two stress responses.

Regression results showing impact of stressors on stress responses

Interestingly, administrative flight stressors were consistently the most important factor in the prediction of all of the measured stress responses. The importance of administrative flight stressors to the measured stress responses may be because training is designed to inoculate crew members to stressors such as the physical/environmental conditions and violent war actions. That type of training makes sense, as those types of stressors have immediate importance. It is vital that crew members block out stressors and maintain focus to successfully and safely complete their assigned missions. Administrative flight stressors, however, are ignored in current training, and there is no training or acknowledgment of their importance for the psychological health of the aircrew. Thus, an important implication is that commanders may wish to focus attention on administrative flight stressors, as it may improve short-term psychological health, which may ultimately impact mission success and safety.

An alternative explanation, however, is that the flight crews have a culture and ethos of strength, and any admission of problems with physical and war stressors would be seen as weakness. As a result, there may be intentional bias in their responses, whereas, on the other hand, the seemingly innocuous administrative flight stressor may have received more accurate responses.

One limitation that deserves greater attention in future research is the longitudinal effects of administrative flight stressors. This research was a one-time cross-sectional study. It could be that administrative flight stressors only have short-term effects on psychological health. While lasting effects are important to examine, the findings from such research would not lessen their short-term importance. Therefore, greater attention should be paid to this type of stressor in the future.


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Weathers, F. W., Litz, B. T., Herman, D. S., Huska, J. A., & Keane, T. M. (1993, October). The PTSD Checklist (PCL): Reliability, validity, and diagnostic utility. Paper presented at the annual meeting of the International Society for Traumatic Stress Studies, San Antonio, TX.

Point of contact (POC) information

For further information about this research effort, please contact the following POCs:

Thomas A. Stetz, PhD
Hawaii Pacific University

LTC Melba C. Stetz, PhD
Hawaii Pacific University