Aircraft Pilots Research Articles

A review of high G-stress induced problems and their solutions

G stress can debilitate pilots of modern fighter aircraft and consequence accidents due to G-induced loss of consciousness (G-LOC). The physiological effects of high G stress include reduction in head level blood pressure and cardiac output that subsequently results loss of vision and G-LOC. The body's natural resistance system helps the pilot to fight against the effects of G stress to some level. To understand the medical and physiological consequences of high G forces on humans, research around the world is conducted using centrifuges, tilt tables, lower body negative pressure (LBNP) devices, etc. Physiological effects due to G-stress are experienced by the pilot on the cardiovascular, respiratory, musculoskeletal and central nervous systems. Many physiological, environmental and habitual conditions are found responsible for decreasing the G-tolerance. Mechanical, physiological and educational countermeasures are suggested to protect the pilots of high performance aircraft against the extreme acceleration. Expected inventions of more manoeuvrable aircrafts will possibly demand the use of advanced countermeasures to protect the pilots from the effect of high G forces.

Speech Spectral Transfer Function

The article discusses the problem of estimating the psychophysiological state of aircraft pilots by their speech. For this purpose, a new concept of an individual speaker’s transfer function is proposed. This definition is based on the classical results of automatic control theory. The article presents the algorithms for calculating transfer function and the examples of using this feature for medical purposes.

Physical fitness and aerobic capacity of Polish military fighter aircraft pilots

Summary Study aim: To determine the level of physical fitness and aerobic capacity of Polish military fighter aircraft pilots. Material and methods: The study was conducted on a group of 120 Polish military fighter aircraft pilots (men). The average age of subject was 37.13 ± 5.42 years. For further analysis, the pilots were divided into three age groups: under 29, aged 30–39, and 40–49. Age criteria were adopted according to the classification used by the American Heart Association. A physical fitness test (seven skills) was used to determine the level of physical fitness of pilots. The Åstrand-Ryhming test and a MONARK cycling ergometer were used to determine the level of aerobic capacity. Results: The pilots obtained the following average results during the physical fitness test: push-ups on a bench – 37.7 reps; shuttle run 10 × 10 m – 30.3 s; pull-ups – 9.1 reps; sit-ups – 54 reps; standing long jump – 228.5 cm; zigzag pattern run – 25.8 s; 50 m swimming – 49.2 s. The physical fitness of military pilots decreases with age. The average level of aerobic capacity of military pilots was estimated at 33.73 ± 5.62 VO2max (ml/kg/min). Conclusions: Polish military fighter aircraft pilots are characterized by a medium level of physical fitness and a medium level of aerobic capacity. The level of aerobic capacity is lower currently than 30 years ago. It is a perturbing and negative phenomenon.

Communication and situation awareness needs of hearing protection systems in high noise environments

The primary mission of aircraft carriers is to launch and recover military aircraft. Critical to the highly choreographed operations on the flight deck of the aircraft carrier is communications between aircraft directors, plane crews, and pilots as well as maintaining situation awareness in a highly dynamic environment. This must occur in an acoustic environment of 110 to 150 + dBA. These noise levels readily exceed the requirements for double hearing protection. A dilemma is generated in trying to provide adequate hearing protection while maintaining critical communications and situation awareness during flight operations at these noise levels. This paper will review previous studies of hearing protection effectiveness, compliance, factors affecting compliance, and impact on job performance in environments that readily exceed legacy hearing protection. To address the situation awareness shortfalls, a tri-service group (US Army, Air Force and Navy) is developing a standard for detection and localization criteria (commonly known as situation awareness) to assess operational suitability. The standard is intended to drive manufacturers to measure beyond the attenuation a hearing protector provides to address operational needs. New products and techniques are presented which demonstrate a potential solution sets to this critical issue.

Seeing the Threat: Pilot Visual Detection of Small Unmanned Aircraft Systems in Visual Meteorological Conditions

One key challenge of integrating Unmanned Aircraft Systems (UAS) platforms into the National Airspace System (NAS) is the potential for midair collisions between manned aircraft and the unmanned system. The lack of an established UAS benchmark for Detect, Sense & Avoid Systems put the preponderance of avoidance efforts on manned aircraft pilots to visually see and avoid potential collision threats. The small size, unusual configurations, and diverse operational applications of unmanned systems make UAS platforms difficult to visually identify. This paper sought to determine the mean visibility distance of small UAS systems (sUAS) to an alerted pilot flying a general aviation aircraft in visual meteorological conditions (VMC). The study evaluated mean visibility distance to various sUAS platforms based on a scripted set of UAS convergence conditions. The study utilized a mixed method design in which a general aviation aircraft was flown into a UAS operations area. Study pilots were instructed to locate a flying UAS aircraft without bearing assistance. Both the UAS and manned aircraft were assigned vertically de-conflicted altitudes with the UAS aircraft executing a series of converging and crossing courses relative to the manned aircraft. The distance at which the pilot visually located the UAS platform was timestamped and electronically recorded via a GPS tracking device. The various conditions were analyzed to determine significant visibility differences among the various convergence conditions. Qualitative data was collected from participant comments and observations recorded by an in-flight safety observer.

Airfoil performance degradation by coupling effects of supercooled raindrop icing and heavy rainfall

Icing and rainfall are the two critical meteorological factors that threaten the aircraft flight safety. A number of previous studies have shown their individual influences on aircraft aerodynamics; however, to date no studies on their coupling effects exist. In this paper, a numerical study is conducted to focus on the aerodynamic performance of a NACA 23012 airfoil exposed to heavy rain in the presence of an ice accretion by supercooled raindrop on the leading edge. An Eulerian–Lagrangian two-phase flow approach developed for rain simulation in our previous work is adopted here with some improvement in the turbulence model. A series of new phenomena about the aerodynamic performance and wake characteristics under the coupling effects of ice accretion and rainfall are found and discussed. These results do not seem to have been published previously and should be of significance to the aircraft industry for improved aircraft design and pilot training.

Personal Flying Accident Rates of Selected Light Sport Aircraft Compared with General Aviation Aircraft.

The issue of expanding flight privileges that do not require medical oversight is currently an important topic, especially in the United States. We compared personal flying accident rates in aircraft with special light sport aircraft (SLSA) and experimental light sport aircraft (ELSA) airworthiness certificates to accident rates for personal flying in other general aviation (GA) aircraft. To calculate accident rates, personal flying hours were obtained from the annual FAA General Aviation and Part 135 Activity Surveys, and numbers of personal flying accidents were obtained from the NTSB accident database. Overall and fatal personal flying accident rates for the SLSA and ELSA groups and other GA aircraft were calculated and accident rates were compared. The overall personal flying accident rate for SLSA and ELSA was found to be 29.8 per 100,000 flight hours and the fatal accident rate was 5.2 per 100,000 flying hours. These are both significantly greater than the overall personal flying rate of 12.7 per 100,000 h and fatal rate of 2.6 per 100,000 h for other GA aircraft. Although this study has several limitations, the significantly higher accident rates in the sport pilot aircraft suggests caution when expanding sport pilot privileges to include larger, more complex aircraft. Mills WD, DeJohn CA. Personal flying accident rates of selected light sport aircraft compared with general aviation aircraft. Aerosp Med Hum Perform. 2016; 87(7):652-654.

Military jet pilots have higher p-wave dispersions compared to the transport aircraft aircrew.

For the purpose of flight safety military aircrew must be healthy. P-wave dispersion (PWD) is the p-wave length difference in an electrocardiographic (ECG) examination and represents the risk of developing atrial fibrillation. In the study we aimed at investigating PWD in healthy military aircrew who reported for periodical examinations. Seventy-five asymptomatic military aircrew were enrolled in the study. All the subjects underwent physical, radiologic and biochemical examinations, and a 12-lead electrocardiography. P-wave dispersions were calculated. The mean age of the study participants was 36.15±8.97 years and the mean p-wave duration was 100.8±12 ms in the whole group. Forty-seven subjects were non-pilot aircrew, and 28 were pilots. Thirteen study subjects were serving in jets, 49 in helicopters, and 13 were transport aircraft pilots. Thirty-six of the helicopter and 11 of the transport aircraft aircrew were non-pilot aircrew. P-wave dispersion was the lowest in the transport aircraft aircrew, and the highest in jet pilots. P-wave dispersions were similar in the pilots and non-pilot aircrew. Twenty-three study subjects were overweight, 19 had thyroiditis, 26 had hepatosteatosis, 4 had hyperbilirubinemia, 2 had hypertension, and 5 had hyperlipidemia. The PWD was significantly associated with thyroid-stimulating hormone (TSH) levels. Serum uric acid levels were associated with p-wave durations. Serum TSH levels were the most important predictor of PWD. When TSH levels were associated with PWD, uric acid levels were associated with p-wave duration in the military aircrew. The jet pilots had higher PWDs. These findings reveal that military jet pilots may have a higher risk of developing atrial fibrillation, and PWD should be recorded during periodical examinations.

An Autonomous Override System to Prevent Airborne Loss of Control

Loss of Control (LOC) is the most common precursor to aircraft accidents. This paper presents a Flight Safety Assessment and Management (FSAM) decision system to reduce in-flight LOC risk. FSAM nominally serves as a monitor to detect conditions that pose LOC risk, automatically activating the appropriate control authority if necessary to prevent LOC and restore a safe operational state. This paper contributes an efficient Markov Decision Process (MDP) formulation for FSAM. The state features capture risk associated with aircraft dynamics, configuration, health, pilot behavior and weather. The reward function trades cost of inaction against the cost of overriding the current control authority. A sparse sampling algorithm obtains a near-optimal solution for the MDP online. This approach enables the FSAM MDP to incorporate dynamically changing flight envelope and environment constraints into decision-making. Case studies based on realworld aviation incidents are presented.

Aptitude and Trait Predictors of Manned and Unmanned Aircraft Pilot Job Performance

Previous research has shown that the same aptitude and trait measures that predict success in U.S. Air Force (USAF) manned aircraft pilot training predict remotely piloted aircraft (RPA) pilot training outcomes with generally similar levels of validity (Carretta, 2013; Rose, Barron, Carretta, Arnold, & Howse, 2014). However, because USAF RPA pilots initially train in manned aircraft, validation of aptitude and traits predictive of RPA pilot success has thus far been limited to RPA pilot training outcomes that actually require manned flight. Hence, thus far, there has been no basis for determining the aptitudes and traits predictive of success in environments in which pilots actually fly RPAs. To address this gap, the present study evaluated preaccession trait (Big Five personality domains) and aptitude (spatial, quantitative, and aviation knowledge) measures as predictors of manned and unmanned aircraft pilot performance on-the-job, as measured by supervisor and senior rater stratification on 3 years of Officer Performance Reports (OPRs). Results were generally consistent in showing that the same aptitudes, knowledge, and personality traits that predict successful job performance for manned aircraft pilots also predict successful job performance for RPA pilots. However, results also showed preaccession aviation knowledge to be a stronger predictor of job performance for RPA pilots than for manned aircraft pilots. These findings and their implications for attracting and selecting RPA pilots are discussed.

Risk Assessment for Subjective Evidence-Based Ethnography Applied in High Risk Environment

Subjective Evidence-Based Ethnography (SEBE) is a family of methods developed for investigation in social science based on subjective audio-video recordings with a miniature video-camera usually worn at eye-level (eye-tracking techniques are included). Despite its application to the analysis of high risk professions (e.g. anesthetists, aircraft pilots, nuclear reactor pilots) and the potential additional risks it induces, no suggestions regarding these concerns and no solutions helping researchers to anticipate this kind of risks are available in the literature. Aiming at filling this gap, we undertook a study of SEBE equipment applied to the analysis of workers’ activities on a nuclear power plant. The method was divided in three phases: i) observations and discussions on full scale simulators of activities undertaken by one or two workers (N=42) to characterize the consequences of the SEBE equipment, ii) bibliographic research combined with results of first phase to elaborate a risk assessment protocol, iii) analysis of its application in real operating situations (N=17). The elaborated protocol gave satisfactory results in terms of risk prevention and time application: No incident or accident occurred and the risk assessment took less than five minutes. The observations highlighted however a risk of side-effect (using SEBE equipment to justify subjects’ mistake or failure) giving greater importance to the necessity of this sort of risk assessment protocol. To date, the protocol needs to be tested in other industrial contexts in order to be improved and/or to confirm its robustness.

A method for cross-task mental workload classification based on brain connectivity

A method for cross-task mental workload classification based on brain connectivity

Cochlear implant features and listening effort induction: measurement of the mental workload experienced during a word in noise recognition task

Cochlear implant features and listening effort induction: measurement of the mental workload experienced during a word in noise recognition task

Non-invasive measurement and subsequent analysis of human carotid pulse for ground based simulation of G-stress

Gravitational G stress can debilitate pilots of modern fighter aircraft which may result in mishaps due to G-induced loss of consciousness G-LOC.The ability to bear G exposure is mainly a role of sufficient blood flow to the brain - the most susceptible and critical organ regarding aircrew performance. Carotid artery is the closest vessel to the heart and brain and is responsible for the blood flow between them. Past studies of high acceleration effects on physiological parameters has concluded that the heart rate variability HRV is the only parameter which can be effectively captured, stored, processed and analysed. Carotid pulse is an important signal to assess HRV. A simple and non-invasive system is developed in which piezoelectric sensor is placed on the carotid artery of the human subject. Raw carotid signal of many human subjects in real time is acquired in different body postures using BIOPAC system. RR interval, heart rate and pulse amplitude are determined using BIOPAC system software. The present work relates the effect of change in heart rate in different body postures to the change in heart rate due to G stress which further can be used for measurement and management of G stress of aircraft pilots.

Observer Based Optimal Vibration Control of a Full Aircraft System Having Active Landing Gears and Biodynamic Pilot Model

This paper deals with the design of an observed based optimal state feedback controller having pole location constraints for an active vibration mitigation problem of an aircraft system. An eleven-degree-of-freedom detailed full aircraft mathematical model having active landing gears and a seated pilot body is developed to control and analyze aircraft vibrations caused by runway excitation, when the aircraft is taxiing. Ground induced vibration can contribute to the reduction of pilot’s capability to control the aircraft and cause the safety problem before take-off and after landing. Since the state variables of the pilot body are not available for measurement in practice, an observed based optimal controller is designed via Linear Matrix Inequalities (LMIs) approach. In addition, classical LQR controller is designed to investigate effectiveness of the proposed controller. The system is then simulated against the bump and random runway excitation. The simulation results demonstrate that the proposed controller provides significant improvements in reducing vibration amplitudes of aircraft fuselage and pilot’s head and maintains the safety requirements in terms of suspension stroke and tire deflection.

Aviation Outreach Model and Gap Analysis: Examining Solutions to Address Workforce Shortages

The purpose of this research is to examine aviation outreach programs to identify best practices and areas for improvement in the endeavor to recruit youth to the aviation industry. The research includes creation of a model of aviation outreach and development and application of an aviation outreach gap analysis design. Three programs are analyzed, Women in Aviation Girls in Aviation Day, Experimental Aviation Association Young Eagles, and Aircraft Owners and Pilots Association High School Aviation Initiative. Each program takes a unique approach to recruiting youth and the strengths and weaknesses, based on the aviation outreach model, are discussed. Results of the research reveal that each of the three outreach programs should be considered a best practice. Recommendations for aviation outreach are provided with emphasis on increased attention to outcome measures. This research contributes a new method to assess outreach programs, a critical task in the effort to create solutions to the global aviation workforce challenges.

Pilot behavior modeling and its application to manual control tasks

Abstract: The modified two pilot behavior models are discussed. One of them is the structural model. Its modification allowed to get better agreement in calculation of variance of error and to evaluate the influence of some new task variables (control element gain coefficient, requirements to the accuracy) on pilot – vehicle system parameters. The other model is the composite model of pilot behavior based on neural network approach. This model provides high agreement between the simulated and experimental pilot frequency response characteristics. The structural model is used for development of the criterion for the of flying qualities prediction in lateral channel with taking into account the influence of motion cues on pilot behavior and for the preliminary design of the predictive display. As for the composite model it was used for development of the flying qualities criterion for the pitch control task based on calculation of pilot and pilot aircraft system frequency response parameters. The additional procedure - the preliminary selection of dynamic configurations from the database was proposed what allowed to get high agreement between the predicted flying qualities level evaluated by the pilots in flight tests.

Robust Active Noise Control System for Fighter Aircraft Pilot Helmet Application

This paper proposes an Active Noise Control (ANC) scheme for fighter aircraft pilot helmet application. The proposed scheme addresses the noise environment inside the helmet to achieve perceivable noise attenuation. It also incorporates algorithms such as energy based detectors to control the operation of ANC system and variable step-size to increase the performance of ANC, to make the system robust. The paper highlights the real-time algorithm development on a DSP processor to meet the real-time resource constraints. The developed ANC system is evaluated in the laboratory for a typical fighter aircraft noise and the results when compared with the performance of existing system, found to be quite promising.

Age and Aortic Diameters in Pilots

Pilots are exposed to various physical and hemodynamic stresses during flight. Aortic dilatation may be one of the important consequences of flight-related stress. In this study, we evaluated whether or not variation in aortic diameter was associated with the type of aircraft and the age of pilots. Medical records of 87 jet aircraft pilots (JP) (mean age = 30.0 ± 7.0 years) and 65 non-jet aircraft pilots (NJP) (mean age = 32.63 ± 5.7) were reviewed. Echocardiographic diameters of the aortic sinus (AoS) and ascending aorta (AoAsc) were measured using standard echo probe positions. Aortic diameters were not statistically different between JP and NJP. Regression analysis revealed that the diameters of the AoS (R = 0.484, R(2) = 0.234, p < 0.001) and AoAsc (R = 0.514, R(2) = 0.264, p < 0.001) were significantly associated with age in the JP group. Whereas, there was not any relationship found between age and the diameters of the AoS and AoAsc in the NJP group. Jet pilots had aortic enlargement as they became older in contrast to the NJP group. Although the aortic diameters were not within the critical ranges in the JP group, these results could suggest that flight-related stresses might result in acute aortic syndromes in the long term.

Career perspective: Victor A. Convertino.

This review focuses on a career of unique opportunities to participate in various areas of research related to extreme physiology and medicine. My experience as a volunteer subject in exercise experiments conducted at NASA included the study of acute and chronic physiological responses and adaptations to exercise in environments of hypoxia, heat stress, and simulated microgravity (bed rest), and eventually to my doctoral work on mechanisms underlying expansion of plasma and blood volume with acute and repeated exercise and heat exposure. My career has taken me to research positions at NASA, the Stanford University School of Medicine, the University of Arizona, and the U.S. Air Force Research Laboratory before assuming my present location at the U.S. Army Institute of Surgical Research. As a result of these multiple experiences across a period of 45 years, I have had opportunities to translate basic research to astronauts, high-performance aircraft pilots, and critically ill patients who are challenged by conditions of extreme physiology and medicine.