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O. Stroosma

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64 records found

Occurrence and impact

Journal article (2026) - D.M.L. Vlaskamp, Alex Pollitt, J. Blundell, A. Landman, Eric L. Groen, M.M. van Paassen, O. Stroosma, Max Mulder
Startle and surprise are known to impair pilot performance during non-normal flight conditions. In the past years research has focused on developing strategies to help pilots mitigate startle and surprise responses to unexpected situations. However, no equivalent research exists for cabin crew. This study investigates the prevalence, impact on crew performance, and emotional consequences of startle and surprise among cabin crew, as well as the way in which it is currently trained. A survey was conducted among 348 European-based cabin crew to gather data on in-flight events that provoked startle, surprise, or both. Objective measures included stress ratings, perceived impact on performance, perceived emotional control, training exposure, and lasting anxiety. Qualitative data were also collected to assess crew responses and coping mechanisms. Out of 348 respondents, 79.3% reported having experienced startle, surprise or both. High stress levels were significantly correlated with perceived performance impairments and lasting anxiety. Current startle and surprise training improved perceived preparedness but did not reduce perceived stress or anxiety. Emotional control was deemed a key protective factor. Startle and surprise can cause operationally significant impact on cabin crew performance. Training that includes simple, effective emotional regulation strategies, such as those developed for pilots, is currently lacking and may help improve both immediate performance and long-term psychological resilience in the cabin environment, as may increased peer-support access. ...
Startle and surprise are known to potentially incapacitate professionals who respond to emergency situations. In the aviation domain, self-management methods to prevent such incapacitation have been introduced for pilots. This study aims to explore the relevance of similar self-management methods tailored for cabin crew, using subjective evaluation by cabin crew and cabin crew instructors. First, a method was designed and refined using interviews and a focus group with nine subject-matter experts, consisting of four steps: protect, reset, check and act. Second, relevance of the method was quasi-experimentally tested by letting 15 cabin crew members apply it in a simulated firefighting scenario. After performing the scenario, they rated whether the method had positive or negative effects, was difficult or easy to use, and they retrospectively rated their perceived stress before and after applying the method. Participants positively rated the method’s effectiveness and usability, and reported the method to significantly reduce perceived stress. Participants provided several suggestions for improving the method, and for approaches to integrate the method more effectively into existing protocols. The outcomes of this study provide direction on the design and use of self-management methods that can help manage startle and surprise in teams. ...
Objective: We aim to investigate how pilots’ startle and surprise responses affect information-processing performance during simulated in-flight events. Background: Startle and surprise are distinct constructs, each with their own potential effects on pilot’s performance during unexpected in-flight events. Prior research suggests that startle may impair performance through stress-induced cognitive interference, whereas surprise may do so via cognitive demands associated with sensemaking. Thus, we hypothesized that both startle and surprise would negatively affect information-processing performance on a secondary auditory cognitive task. Method: Using a motion-based hexapod simulator and a twin-propeller aircraft model, 26 pilots each performed eight single-pilot flight scenarios, which were designed to elicit varying levels of startle and surprise responses. Linear mixed-effects models were employed to analyse the relationships between self-report startle and surprise with secondary task performance, while controlling for individual differences and differences between the scenarios. Results: The results revealed that higher startle was significantly associated with reduced information-processing speed. For surprise, no significant association was found. Conclusion: The findings suggest that, within the context of the tested scenarios, startle appeared to impose a more pronounced disruptive effect on pilots’ information-processing performance than surprise. Application: The study underscores the need for tailored interventions to enhance pilots’ resilience to startle and calls for further research on ecologically valid methods to induce surprise for research and training purposes. ...
Journal article (2026) - Direnc Atmaca, Olaf Stroosma, Erik-Jan van Kampen
Commercial applications of flying wing aircraft present a unique opportunity to improve fuel efficiency in aviation but also pose significant challenges in stability and control. This paper improves the existing flight control laws of a commercial flying wing concept called the Flying V. The paper designs and evaluates normal law flight controls through piloted flight simulations on a moving base flight simulator, assessing handling qualities, certification compliance, and flight envelope protection capabilities. Industry-inspired outer guidance loops include envelope protections for angle of attack, bank, pitch, and load factor, using command-limiting exponential potential functions to smoothly enforce limits and prevent longitudinal instability. The inner loop employs incremental nonlinear dynamic inversion. Results demonstrate that the Flying V model, augmented with the proposed controller, achieves Level 1 handling qualities and meets nearly all certification requirements. Flight envelope protection maneuvers confirm that exponential potential functions deliver protection performance comparable to commercial aircraft and successfully prevent unstable behavior. ...
Conference paper (2026) - D. Atmaca, O. Stroosma, E. van Kampen
Commercial applications of flying wing aircraft present a unique opportunity to improve fuel efficiency in aviation, but also pose significant challenges in stability and control. This paper improves the existing flight control laws of a commercial flying wing concept called the Flying-V. The paper designs and evaluates normal law flight controls through piloted flight simulations on a moving base flight simulator, assessing handling qualities, certification compliance, and flight envelope protection capabilities. Industry-inspired outer guidance loops include envelope protections for angle of attack, bank, pitch, and load factor, using command limiting exponential potential functions to smoothly enforce limits and prevent longitudinal instability. The inner loop employs incremental nonlinear dynamic inversion. Results demonstrate that the Flying-V model, augmented with the proposed controller, achieves Level 1 handling qualities and meets nearly all certification requirements. Flight envelope protection maneuvers confirm that exponential potential functions deliver protection performance comparable to commercial aircraft and successfully prevent unstable behavior. ...
This manual provides guidance for human factors researchers and applied psychologists, on the standardized and scientifically rigorous use of the instruments. It is structured to include an overview of the instruments, administration guidelines, and a summary of their psychometric properties to support accurate application and interpretation in research and operational contexts. ...
This paper presents the development process of an aircraft control law. The control law is designed using a two-degree-of-freedom (2DoF) structured H∞ loop-shaping approach. This method allows the reuse of controller structures required by certification procedures while directly including handling qualities and robust stability requirements in the optimization process. This strategy is employed to develop a Rate Command and Attitude Hold (RCAH) demand system aimed at satisfying longitudinal handling qualities. First, the stability of the open-loop model and its compliance with the handling qualities guidelines are evaluated. Then, the control law is designed, with a detailed description provided of the design specifications and their formulation in the context of H∞ control. Subsequently, the controller parameters are optimized to satisfy the design specifications and a closed-loop analysis is performed. Finally, a simulator flight testing campaign is conducted to experimentally validate the designed control law. It is shown that the aircraft equipped with the RCAH system achieves better handling quality ratings (HQRs) and more favorable pilot feedback, providing a substantial improvement over the bare airframe. ...
We investigated the effect of personality traits and flight experience on pilot cognitive and affective responses across seven startling and surprising scenarios performed in motion-based simulators. A dataset of 89 airline pilots from four studies was used. The personality traits measured were trait anxiety, decision-related action orientation (AOD), and failure-related action orientation (AOF). Pilot self-reported responses in scenarios were standardized by obtaining z scores of startle, surprise, stress, and mental workload. Only trait anxiety was found to be significantly positively correlated with stress. No significant effects of AOD, AOF, or flight hours were found on pilots’ responses. The results indicate trait anxiety may affect pilots’ responses to stressful scenarios, even though pilots are selected based on low trait anxiety. ...
This paper outlines the three-phase construction of the Startle and Surprise Inventories (Startle-I; Surprise-I) and Visual Analogue Scales for Startle and Surprise (Startle-VAS; Surprise-VAS). In Phase 1, seven experts in the field assessed the content validity of 14 items for surprise, 7 items for startle derived from fundamental and applied literature. Elimination of items was based on a 50% agreement of relevance. In Phase 2, 81 participants completed the retained 19 items nine times, each time immediately after watching a video clip. A multilevel exploratory factor analysis was applied to assess the construct validity of items. In Phase 3, concurrent validity of the Startle-VAS and Surprise-VAS was tested by comparing with the Startle-I and Surprise-I scores, respectively. The first two phases yielded a 11-item two-factor solution, corresponding to the constructs of startle and surprise. These results supported Startle-I and Surprise-I as measures of self-report startle and surprise, with Startle-VAS and Surprise-VAS as efficient alternatives. ...
Providing adequate simulator motion cues for simulated upset and stall scenarios remains challenging. This paper evaluates the potential of novel optimization-based motion cueing algorithms for upset and stall simulation. An offline analysis is performed to compare three Model Predictive Control (MPC) algorithms with varying prediction horizon lengths and prediction strategies (i.e., "Oracle", "Perfect", and "Constant") against two baseline classical washout algorithm implementations from literature. The analysis is performed for a symmetric stall scenario flown with TU Delft's Cessna Citation II laboratory aircraft. Overall, the analysis shows that the objective motion cueing quality expressed in terms of the Root Mean Square Error (RMSE) improves by 29.8% (for specific forces) and 18.7% (for rotational velocities) with the "Oracle" and "Perfect" MPC implementations compared to the reference classical washout results. For the "Constant" MPC algorithm, which in fact does not include any explicit prediction across the MPC algorithm's future prediction window, only a marginal improvement in motion quality was found. Overall, these results imply that, assuming a sufficient future reference motion prediction can be achieved, optimization-based motion cueing algorithms have the potential to provide significantly better motion cueing quality compared to classical motion cueing algorithms. ...
Conference paper (2025) - D. Atmaca, O. Stroosma, E. van Kampen
The Flying-V is a novel flying wing aircraft design that aims to improve aerodynamic efficiency and fuel consumption. In recent years, there has been an increased effort to evaluate the handling qualities (HQs) of the Flying-V, and to develop new flight control strategies. One of the latest flight control designs for the Flying-V uses Incremental Nonlinear Dynamic Inversion (INDI) with a Flight Envelope Protection system. The purpose of this research is to validate this FCS design and its conclusions on handling qualities by conducting piloted experiments. To facilitate a sound comparison, the aerodynamic model, flight control structure, and airframe characteristics are taken as is from the existing study. For the experiment, numerous maneuvers are designed and carried out. The experiment is performed on the SIMONA Research Simulator of the Delft University of Technology, with three real-life test pilots as participants. The results show a significant correlation with offline findings and demonstrate the improvement in HQs provided by the flight control system. ...
Previous studies have indicated that the attitude director indicator (ADI) used in commercial aviation is suboptimal in representing the bank angle direction, which can lead to confusion, roll reversal errors and increased workload. Confusion about the bank angle direction has been implied in several cases of loss of control in-flight (LOC-I). In the current study, we therefore tested whether bank angle representation can be improved by adding non-disruptive visual depth cues to the ADI. An enhanced ADI was created, in which three monocular cues were added: atmospheric haze (i.e. a gradient in color towards the horizon), a shadow line under the aircraft symbol, and perspective lines on the ground. Airline pilots (n = 25) were tasked with rolling back to level 96 times from unforeseen (30 or -30 degrees) bank angles after experiencing either matching or mismatching (disorienting) roll motion cues in a motion-base simulator. There was no outside visibility and pilots responded using the ADI only. Roll reversal errors and reaction times were compared within-subject between the enhanced and baseline ADI, which were both based on the B747. Pilots were tasked to respond immediately upon presentation of the display, so that their initial interpretation of bank angle direction could be measured. There was no significant difference in roll reversal errors, and a significant increase in reaction times, when using the enhanced ADI compared to the baseline ADI. This suggests that pilots had slightly more difficulty with reading the bank angle with the enhanced ADI. Of the pilots, 56% preferred the enhanced ADI over the baseline display as it is, 8% had no preference and 36% preferred the baseline ADI. The most valued addition was the perspective lines on the ground, which pilots remarked would also be helpful in recovering extreme attitudes. The most-heard concerns were about potential clutter caused by the added cues, and difficulty with accurate reading of the pitch angle due to the shadow lines. In conclusion, according to the pilots' feedback, the addition of depth cues to the ADI appears promising, but it should be tested using more challenging tasks. Further design changes also appear needed to prevent clutter and facilitate quick reading of the aircraft attitude. ...
Conference paper (2025) - O. Stroosma
Motion cues are one of the most challenging aspects of human-in-the-loop vehicle simulators. The real vehicle cues can only be presented in a highly distorted way, so it is important to understand what these cues look like and which aspects are important for the human controlling the vehicle. This paper describes two complementary ways of assessing (translational) motion cues: accelerations plus gravity, and specific forces. These perceived cues can be constructed from different components of Newton’s Second Law and are fundamentally equivalent. The paper shows how the situation heavily favors one representation or the other in understanding the motion cues to be presented. When assessing the cues in flight, the specific force formulation is superior as it leverages flight dynamics knowledge and intuition to predict and explain the form of the cues. The paper gives a number of examples to illustrate this claim, supported both by analysis and by measurements in an instrumented business jet and a motion-based flight simulator. ...
We tested whether pilots would detect low-salient controllability problems more quickly during manual compared to automated flight. Using a moving-base simulator and a Piper Seneca aerodynamic model, airline pilots (n = 20) performed scenarios in which either a gradually ensuing single-engine failure or an icing accumulation occurred. Both scenarios were performed once during manual flight and once during automated flight, and were alternated with distraction scenarios. The icing accumulation was detected marginally significantly more quickly during manual flight, while there was no significant difference for the engine failure. Problems in manual flight were, as expected, most likely discovered from aircraft motions or control forces. Interestingly, there were several late detections during manual flight which appeared to be caused by subconscious manual corrections. In automated flight, the engine failure was discovered most often from the engine manifold pressure indication, while the icing accumulation was most often discovered from control column movement. The results therefore underline the importance of using back-driven controls, and further indicate that manual flight does not necessarily improve detection of problems that occur without display indications. ...

Reported prevalence and application of mitigation strategies

Journal article (2025) - D.M.L. Vlaskamp, Alex Pollitt, James Blundell, H.M. Landman, Eric L. Groen, M.M. van Paassen, O. Stroosma, Max Mulder
Startle and surprise can impair pilot performance and affect flight safety. This study investigates the prevalence of different startle and surprise events among helicopter pilots, its impact on pilot stress and mental effort and the influence of training background. It also looks at currently used startle mitigation strategies and evaluates the usability of a previously proposed “Aviate, Breathe, Check (ABC)” startle management method (Piras et al. 2023). A survey among 234 helicopter pilots revealed that 96% had experienced impactful startle or surprise events during operations. Scenarios such as disorientation, tail rotor incidents, and flight into instrument meteorological conditions (IMC) were considered particularly stressful. Reported levels of stress and mental effort during startle and surprise events did not differ between pilots with higher and lower experience levels or between pilots with a different training background (military or civilian). Only 38% of pilots indicated they were specifically trained to deal with startle and surprise and only 1% were trained to use a breathing technique. Most pilots (90%) expressed openness to implementing the ABC method and expected benefits from using it. Concerns regarding time constraints in critical situations emerged as the primary objection to adopting this technique. Overall, the findings indicate that the introduction of a startle management method tailored for helicopter operations could significantly enhance safety, especially given the higher accident rates compared to fixed-wing operations. Future research should focus on developing effective training protocols that account for the unique challenges of helicopter flying. ...
Journal article (2024) - F.W. Evertsen, H.M. Landman, Eric L. Groen, Mark Houben, M.M. van Paassen, O. Stroosma, Max Mulder
Objective
We aimed to find objective measures of the impact of spatially disorienting (SD) stimuli on pilot cognition in an ecologically valid environment.
Background
SD frequently occurs in military rotary-wing operations and often contributes to mishaps. Effects of SD stimuli on pilots are usually quantified using control errors, but effects on cognition have not yet been successfully quantified.
Method
Military helicopter pilots (n = 14) performed scenarios with six SD stimuli (SD condition) and six corresponding control stimuli (NoSD condition) in a motion-base simulator with integrated virtual reality headset. SD stimuli were: false horizon, featureless terrain, leans, brownout, a somatogyral yaw illusion, and loss of horizon due to night vision goggles (NVGs). Mental workload was measured using auditory arithmetic task performance and attentional focus was measured using eye-tracking.
Results
Average arithmetic task performance was significantly impaired, and proportional gaze dwell time on the attitude indicator was significantly increased in the SD compared to the NoSD condition. Of the six SD stimuli, the featureless terrain, the leans, and the brownout induced significant effects on performance, whereas the featureless terrain, brownout, and false horizon significantly affected gaze behavior. The NVGs and somatogyral yaw stimuli did not induce significant effects. Pilots’ self-reports indicated awareness of all SD stimuli, except for the featureless terrain.
Conclusion
The results indicate that SD impacts pilot mental workload and attentional focus.
Application
Modern military aircraft present a large volume of mission-related information to pilots. This study shows that SD stimuli may negatively impact the processing of such information. ...
Journal article (2024) - Jordy K.van Leeuwen, Annemarie Landman, Eric L. Groen, Randall J. Mumaw, Olaf Stroosma, Marinus M.van Paassen, Max Mulder
Previous research indicated a need to improve pilot training with regard to understanding of autopilot logic and behavior, especially in non-routine situations. Therefore, we tested the effect of problem-based exploratory training on pilots’ understanding of autopilot functions. Using a moving-base flight simulator, general aviation pilots (n = 45) were trained to diagnose failures either without foreknowledge and guidance (exploratory group), without foreknowledge but with some guidance (exploratory-guidance group) or with foreknowledge and full guidance (control group). They subsequently performed six test scenarios in which their understanding of the effects of failures was tested by requiring them to deduce the failures and select autopilot modes that were still functioning. Those who received exploratory training with guidance were significantly more likely than the other groups to diagnose failures correctly. The exploratory training group also selected the most appropriate functioning autopilot modes significantly faster than the control group. The results suggest that exploratory training with an appropriate level of guidance is useful for gaining a practical understanding of autopilot logic and behavior. Exploratory training may help to improve transfer of training to operational practice, and prevent automation surprises and accidents. ...