Fear of Flying: Sensitivity to suffocation signals

Summary of Research Findings

The focus of Bogaerde, Derom and Raedt’s 1 2011, experimental research was to understand the relationship between participants self-disclosed symptoms of fear of flying, their accuracy at a task with manipulated respiratory loads and their ability to detect changes in respiratory load in comparison to participants with no fear of flying.

Table 1: Participants response to RIR task
Fear of Flying Group Control Group
Mean Standard Deviation Mean Standard Deviation
Interference Task of Respiratory Load RT Load Trial 310.15 70.44 300.24 67.24
RT Non-Load Trial 300.83 71.94 287.72 55.22
Change in detection rates 9.32 12.52
Percentage Change 3.098% 4.351%

Table 1 illustrates the difference in accuracy participants have in completing the RIR task.

Table 2: Detection of respiratory load task
Fear of Flying Group Control Group
Mean Standard Deviation Mean Standard Deviation
Detection Task Accuracy 1.21 1.55 -0.72 2.94
Rank of Accuracy 23.06 15.16

Table 2 compares the ability of both groups to detect a respiratory load. The comparison is significant between the two groups. The Fear of Flying Group was significantly more able to detect a change in respiratory load. This would suggest that there is a correlation between the self-reporting of a fear of flying and the ability to detect changes in respiratory load. However, participants in the Control Group have a smaller standard deviation in their results, which shows that their results were less varied, resulting in a stronger likelihood that the mean is more consistent with the group.

Table 3: Reporting of flight anxiety symptoms
Fear of Flying Group Control Group
Mean Standard Deviation Mean Standard Deviation Difference between FFG and CG
FAS Anticipation 36.53 9.51 13.42 2.17 63.26%
In Flight 35.37 9.43 14.74 1.05 58.33%
Association 10.00 2.16 7.00 0.33 30.00%
FAM Somatic 20.84 8.51 12.05 1.03 42.18%
Cognitive 20.05 7.16 7.58 0.90 62.20%

Table 3 illustrates that the Fear of Flying Group had a significantly greater reporting of symptoms associated with a fear of flying as detected by the three questionnaires.

Study's Scope

Bogaerde, Derom and Raedt 1 studied the correlation between the ability of people with a fear of flying to recognize respiratory signals and their experience of bodily sensations associated with suffocation signals. This was prompted by an earlier study by Harding and Mills 2 (1983) who operationalized hypoxia by subjecting participants to increased respiratory loads. Although hypoxia is linked to the most severe form of flight phobia, which is situational, nevertheless the study was considered important as it may inform current interventions in the treatment of fear of flying, estimated to include 40% of the population (Van Gerwen, Pinhoven, Diekstra & Van Dych, 1997, cited in article1).

This study presents two hypothesis;

  1. In fearful subjects administration of a respiratory load would deteriorate reaction times on a task in a more pronounced way when compared to subjects who were not fearful
  2. Fearful subjects would show higher accuracy in detecting respiratory loads


Research approach

The research approach used a combination of two tasks and a set of questionnaires. The first task was a random interval repetition (RIR) task to assess subjects accuracy at a task with various respiratory loads. The second task asked subjects to indicate when they detected a change in respiratory load.
Three questionnaires (all previously designed and used); Flight Anxiety situations questionnaire (FAS), Flight Anxiety Modality Questionnaire (FAM) and Anxiety Sensitivity Index (ASI), were administered to all participants after the physical testing. The total number of questions asked was 66. The questionnaires were used to differentiate between the two groups. However asking so many questions, errors surrounding question fatigue and compliance should be considered.

Bogaerde, Derom and Raedt1 compared the sample results to that of a clinical group, with all sample results falling within 2 standard deviations of the clinical group. While this comparison implies internal consistency, without a given clinical sample size, this cannot be assumed.

Two Body Sensation questionnaires are also used (BSQ-R1 and BSQ-R2), this is a further 34 questions, adding to the pressure of fatigue and compliance of the participants. The BSQ has been used in previous studies and is reported as having good reliability. However, when used in this present study the instructions and scales were modified. The reliability therefore should have been re-calculated.

Sensitivity to bodily sensations was operationalised by exposing subjects to a respiratory load via a mask. The apparatus was previously used in a study of suffocation. However the results of this study are not mentioned anywhere in this article, particularly in regard to compensation regarding possible effects of using the mask. There is however a slight discussion that the first BSQ should have been administered just after the mask was put on and before the first task was conducted.


The sample sized used in this research is too small to be able to make accurate generalizations for the population. The research also compares results of a flight anxiety modality questionnaire (FAM) and a flight anxiety situations questionnaire (FAS) with respondents in a fear of flying group (FFG) and a group of subjects who were currently seeking clinical treatment for fear of flying. The study should have focused more on the results of the clinical group as they more accurately represent the population with a fear of flying, rather than those who believe that they have a moderate fear. There is an error in the reporting of the average age of participants in the FFG. The average age of a participant is reported at 27.9 years old, however the range of ages given is only 18-25years with a standard deviation of 1.9 years. The young sample group, limits the ability of the results to be generalized to the population. It is quite possible that older people can have different sensitivity to respiratory signals. There is also no disclosed control for participants with medical conditions. Medical conditions such as asthma could have a profound effect on a participants sensitivity to respiratory signals.


This research is of an experimental research design aided by three questionnaires.


RIR task
Independent variables were changes in respiratory load as applied to the subject’s mask (ordinal variable).
The dependent variable was the subject’s accuracy at assigned tasks (continuous variable).

Detection of respiratory load task
Independent variables were changes in respiratory load as applied to the subject’s mask (ordinal variable).
The dependent variable was the detection or non detection of a respiratory load (ordinal variable).


The procedure used in this research was straightforward. First potential participants were screened about their anxiety towards taking a flight. The results from this determined the participant allocation into groups (Fear of Flying group or Control Group). Participants were then required to take part in the Random Interval Repetition Task (RIR)- a tone detection task. This was then coupled with two tasks where the participants awareness of the respiratory loads being added was tested. After each test participants reported on their bodily sensations experienced. The three questionnaires; Flight Anxiety Situations Questionnaire (FAS), Flight Anxiety Modality Questionnaire (FAM) and the Anxiety Sensitivity Index (ASI) were then administered to all participants.

Data analysis

There was significant data analysis conducted on this research including; ANOVA, T-test, Wilcoxon Rank Sum Test and Non-parametric Spearman's Rho. Completing an ANOVA after multiple T-tests have been completed, helps reduce Type I errors and analyses the variance between different groups. The Wilcoxon Test is used to prove internal validity (assumes data is from the same population, data is measured on ordinal scale and distribution is symmetric around the median). Spearman’s Rho was used to measure the statistical dependence between the two variables. However, a greater analysis to be used would have been a meta-analysis which would have provided more information on central tendency and effect size. Having some analysis regarding correlation between anticipation and reports of bodily sensations would have been useful to aid with the analysis of the research.

Generalization potential

Although this study provides some insight into the ability of subjects with a fear of flying to accurately recognize respiratory signals and their experience of bodily sensations associated with suffocation signals, the study does have a limited application. The reasons for the limited application are; small sample size, having a non-representative sample of the population, operationalizing increased awareness of bodily sensations by increasing respiratory load but not controlling for health factors or fear of suffocation, and recognizing that fear of flying is situational but not replicating this situation in the study.

1. Bogaerde, Derom & Raedt (2011). Increased interoceptive awareness in fear of flying: Sensitivity to suffocation signals. Elsevier. Belgium, 2012. pages 427-432.
2. Harding, R. M., & Mills, F. J. (1983). Aviation medicine- problems of altitude.1. Hypoxia and hyperventilation. British Medical Journal, 286(6375), 1408-1410

More information regarding materials used in this research can be found at:

  • Chambless, D. L., Caputo, G. C., Bright P., & Gallagher, R. (1984). Assessment of fear of fear in agoraphobics- the body sensations questionnaire and the agrophobic cognitions questionnaire. Journal of Consulting and Clinical Psychology, 52(6), 1090-1097
  • Kroeze, S., Van der Does, A. J. W., Spinhoven, P., Schot R., Sterk, P. J., & Van den Aardweg, J. G. (2005). Automatic negative evaluation of suffocation sensations in individuals with suffocation fear. Journal of Abnormal Psychology, 114(3), 466-170
  • Van Gerwen, L. J., Spinhoven, P., Van Dyck, R., & Diekstra, R. F. W. (1999). Construction and psychometric characteristics of two self-report questionnaires for the assessment of fear of flying. Psychological Assessment, 11(2), 146-158
  • Vancleef, L. M. G., Peters, M. L., Roelofs, J., & Asmundson, G. J. G. (2006). Do fundamental fears differentially contribute to pain-related fear and pain catastrophizing? An evaluation of the sensitivity index. European Journal of Pain, 10(6), 527-536.

Contributors to this page

Kirsty Jamieson

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