Cardiovascular Biomarkers' Inherent Timescales in Mental Workload Assessment During Simulated Air Traffic Control Tasks

One central topic in ergonomics and human-factors research is the assessment of mental workload. Heart rate and heart rate variability are common for registering mental workload. However, a major problem of workload assessment is the dissociation among different workload measures. One potential reason could be the disregard of their inherent timescales and the interrelation between participants' individual differences and timescales. The aim of our study was to determine if different cardiovascular biomarkers exhibit different timescales. We focused on air traffic controller and investigated biomarkers' ability to distinguish between conditions with different load levels connected to prior work experience and different time slots. During an interactive real-time simulation, we varied the load situations with two independent variables: the traffic volume and the occurrence of a priority-flight request. Dependent variables for registering mental workload were the heart rate and heart rate variability from two time slots. Our results show that all cardiovascular biomarkers were sensitive to workload differences with different inherent timescales. The heart rate responded sooner than the heart rate variability features from the frequency domain and it was most indicative during the time slot immediately after the priority-flight request. The heart rate variability parameters from the frequency domain responded with latency and were most indicative during the subsequent time slot. Furthermore, by consideration of biomarkers' inherent timescales, we were able to assess a significant effect of work experience on heart rate and mid/high frequency-band ratio of the heart rate variability. Results indicated that different cardiovascular biomarkers reveal different inherent timescales.

A portable primary radar for general aviation

A detailed situation awareness of the local environment is essential for safe flight in General Aviation. When operating under Visual Flight Rules, eyesight is crucial for maintaining situation awareness and objects may be overlooked. Technical solutions such as Flarm have been sought, but they only work on a basis of co-operation: obstacles without the proper equipment are invisible. Recent developments in the field of radar technology, partly empowered by the demand for sensors for autonomous cars, have improved the size and power consumption of available hardware. Today, the hardware exists to build a portable primary radar system for situation awareness. In this paper the results are presented of efforts to build the first portable primary radar for general, which has to be lightweight, cheap and have a low power consumption. The focus in this paper is on the software design of such a radar system. The physical principles of radar sensing are described, as well as the scientific steps needed to provide situation awareness. The hardware and software for the radar are both built and tested, and the results of these tests are presented. A flight experiment is performed with a small aircraft flying past a stationary radar on a small hill. It is found that the radar is capable of detecting the aircraft up to a distance of at least 3 kilometers. 3D localization is performed and the location determined by the radar was on average 46 meters away from the aircraft position as measured by satellite navigation, relative to a total distance of about 1000 meters from the radar. A low-pass filter can be applied on the raw results in order to improve the location estimation further. Future research will focus on bringing the portable radar in motion while operating.

Line-of-sight in operating a small unmanned aerial vehicle: How far can a quadcopter fly in line-of-sight?

A field study was conducted to investigate the probabilities of human participants to detect a small unmanned aerial vehicle (UAV) at a certain distance. A Phantom 4 quadcopter was remotely controlled to hover at one of the 32 pre-determined locations in the air. Thirty-two participants on the ground were requested to judge if they could see the quadcopter on a four-point scale: 1. definitely yes, 2. probably yes, 3. probably no, and 4. definitely no. The participants also responded whether they could hear the quadcopter on the same four-point scale. Logistic regression models were established to estimate the probability of detecting the quadcopter in the air, both visually and auditory. When navigating a quadcopter flying away from the operator, the sound stimulus diminished and then disappeared earlier than that of the sight of the quadcopter. The results of the study indicated that the probability of visual detection of the quadcopter at a distance of 300 m was approximately 0.3. When adopting a 50% probability of visual detection and the "definitely or probably yes" criterion, the estimated distance of line-of-sight was 245 m. The corresponding visual angle was 0.065°. The information in this study is valuable for drone operators, operator training institutes, and drone designers. The aviation authorities may also consider revising the codes or regulations for small UAV operation based on our findings.

An Innovative Technique for Identification of Missing Persons in Natural Disaster Based on Drone-Femtocell Systems

The recent development of the IoT (Internet of Things), which has enabled new types of sensors that can be easily interconnected to the Internet, will also have a significant impact in the near future on the management of natural disasters (mainly earthquakes and floods) with the aim of improving effectiveness in research, identification, and recovery of missing persons, and therefore increasing the possibility of saving lives. In this paper, more specifically, an innovative technique is proposed for the search and identification of missing persons in natural disaster scenarios by employing a drone-femtocell system and devising an algorithm capable of locating any mobile terminal in a given monitoring area. In particular, through a series of power measurements based on the reference signal received power (RSRP), the algorithm allows for the classification of the terminal inside or outside the monitoring area and subsequently identify the position with an accuracy of about 1 m, even in the presence of obstacles that act in such a way as to make the propagation of the radio signal non-isotropic.

U.S. Army Parachute Mishap Fatalities: 2010-2015

INTRODUCTION: Despite the large number of U.S. military members who conduct parachuting operations, its inherent safety risks, and the introduction of a new military parachute in 2010, little has been published in the last decade on U.S. military parachute fatalities.METHODS: Parachute fatality investigative records maintained by the U.S. Army Combat Readiness Center were reviewed for U.S. Army fatalities resulting from military parachuting operations from January 1, 2010, through December 31, 2015. De-identified data on cases were collected, including causes, lethal injuries, and demographic, environmental, and missional factors. A descriptive analysis was performed.RESULTS: There were 13 cases which met study inclusion criteria. Most occurred during static-line operations and were jumps from a C-17 aircraft using a T-11 parachute. The two most common assigned accident codes were "improper or abnormal exit" and "unstable or improper body position," which combined accounted for 33% of cases. Also noteworthy at 11% each were "entanglement," "parachute malfunction," and "dragged on the drop zone," and at 6% each were "static line injury," "lost or stolen air," and "drop zone hazard." In 69% of cases blunt force trauma was the cause of death.DISCUSSION: Incident factors included human actions, equipment failure, and the environment. Death from blunt force trauma upon impact with the ground as the most frequent lethal injury was expected for parachute operations. This descriptive study provides awareness to military leaders of circumstances in which fatalities occur. Future investigations should include data on the total number of jumps to provide a more comprehensive analysis of risk.Johnson ES, Gaydos SJ, Pavelites JJ, Kotwal RS, Houk JE. U.S. Army parachute mishap fatalities: 2010-2015. Aerosp Med Hum Perform. 2019; 90(7):637-642.

Use of Highways in the Sky and a virtual pad for landing Head Up Display symbology to enable improved helicopter pilots situation awareness and workload in degraded visual conditions

Flight within degraded visual conditions is a great challenge to pilots of rotary-wing craft. Environmental cues typically used to guide interpretation of speed, location and approach can become obscured, forcing the pilots to rely on data available from in-cockpit instrumentation. To ease the task of flight during degraded visual conditions, pilots require easy access to flight critical information. The current study examined the effect of 'Highways in the Sky' symbology and a conformal virtual pad for landing presented using a Head Up Display (HUD) on pilots' workload and situation awareness for both clear and degraded conditions across a series of simulated rotary-wing approach and landings. Results suggest that access to the HUD lead to significant improvements to pilots' situation awareness, especially within degraded visual conditions. Importantly, access to the HUD facilitated pilot awareness in all conditions. Results are discussed in terms of future HUD development. Practitioner Summary: This paper explores the use of a novel Heads Up Display, to facilitate rotary-wing pilots' situation awareness and workload for simulated flights in both clear and degraded visual conditions. Results suggest that access to HUD facilitated pilots' situation awareness, especially when flying in degraded conditions.

Future technology on the flight deck: assessing the use of touchscreens in vibration environments

Use of touchscreens in the flight deck has been steadily increasing, however, their usability may be severely impacted when turbulent conditions arise. Most previous research focusses on using touchscreens in static conditions; therefore, this study assessed touchscreen use whilst undergoing turbulent representative motion, generated using a 6-axis motion simulator. Touchscreens were tested in centre, side and overhead positions, to investigate how turbulence affected: (1) error rate, movement times and accuracy, (2) arm fatigue and discomfort. Two touchscreen technologies were compared: a 15" infra-red and a 17.3" projected capacitive touchscreen with force sensing capability. The potential of the force sensing capability to minimise unintentional interactions was also investigated. Twenty-six participants undertook multi-direction tapping (ISO 9241; ISO 2010 ) and gesture tasks, under four vibration conditions (control, light chop, light turbulence and moderate turbulence). Error rate, movement time and workload increased and usability decreased significantly, with screen position and increasing turbulence level. Practitioner Summary: This study evaluated the use of infra-red and projected capacitive touchscreen technologies using multi-directional tapping and gesture tasks, whilst being subjected to different levels of turbulence representative motion. Performance degraded significantly with increasing turbulence level and touchscreen location. This has implications for future flight deck design.

Tactile Display Design for Flight Envelope Protection and Situational Awareness

Spatial disorientation and visual channel saturation are defined as critical situations encountered by military pilots. Such subjects are interesting research areas likely to create innovative systems able to surmount obstacles of this kind. The integration of new stimulation techniques (sensory substitute, adjunct for visual and audio feedback) may be considered to make the visual channel better. This contribution may help in integrating tactile stimulation to improve or substitute the visual channel. It may also help to better interpret the spatial disorientation awareness signals and the vestibulo-ocular response limitations. The innovation of the proposed approach translates in: (i) the development of the PI-Inverse dynamics controller to provide a time delay reduction of the low cost tactile actuator, and thus, high-performance tactile system; (ii) an approach based on fuzzy logic controller (FLC) is being used in order to translate the turn rate angle, the flight path climb angle and the warning messages into tactile signal features instead of a conventional approach based on direct coding of the pitch and bank angles; and (iii) the consideration of the flight envelope. The fuzzy set translation of flight parameters into tactile signals is also a pragmatic and useful way to design the system.

Medical Applications of Drones for Disaster Relief: A Review of the Literature

INTRODUCTION

Rapid progress has been made with unmanned aerial systems (UAS), which are now used in a wide variety of different fields, including media, agriculture, wildlife, and infrastructure. However, the application of UAS for medical purposes, and in particular disaster relief efforts, has been slower to develop. This paper will review and present pertinent studies in the literature.

METHODOLOGY

Studies related to drones and medical applications for disaster relief were identified as part of a larger search regarding the civilian application of drones. A search for civilian drone applications was performed in the EBSCO (Elton B. Stephens Company) database. Non-civilian applications as well as redundant sources were excluded.

RESULTS

The search identified 711 sources pertaining to civilian drone applications. Of these, 117 involved drone applications in disaster relief, and 28 articles specifically addressed medical uses.

CONCLUSION

Drones can be useful during immediate and non-immediate medical disaster relief efforts. They can provide an instant telecommunications infrastructure, assist in telemedicine-enabled clinical services, perform equipment/drug/patient delivery, enhance search and rescue efforts, assess damage and map disaster zones. Rapid processing of permission for emergency operations, promotion of industry expansion, public awareness, and public participation must be emphasized for these to become routine applications. There is a major concern about the organizational umbrella that would promote this initiative. Creation of an organization such as a Drone Civil Air Patrol Wing (DCAPW) could improve our ability to provide post-disaster healthcare delivery services.

Use of unmanned aerial vehicles for efficient beach litter monitoring

A global beach litter assessment is challenged by use of low-efficiency methodologies and incomparable protocols that impede data integration and acquisition at a national scale. The implementation of an objective, reproducible and efficient approach is therefore required. Here we show the application of a remote sensing based methodology using a test beach located on the Saudi Arabian Red Sea coastline. Litter was recorded via image acquisition from an Unmanned Aerial Vehicle, while an automatic processing of the high volume of imagery was developed through machine learning, employed for debris detection and classification in three categories. Application of the method resulted in an almost 40 times faster beach coverage when compared to a standard visual-census approach. While the machine learning tool faced some challenges in correctly detecting objects of interest, first classification results are promising and motivate efforts to further develop the technique and implement it at much larger scales.

UAS stealth: target pursuit at constant distance using a bio-inspired motion camouflage guidance law

The aim of this study is to derive a guidance law by which an unmanned aerial system(s) (UAS) can pursue a moving target at a constant distance, while concealing its own motion. We derive a closed-form solution for the trajectory of the UAS by imposing two key constraints: (1) the shadower moves in such a way as to be perceived as a stationary object by the shadowee, and (2) the distance between the shadower and shadowee is kept constant. Additionally, the theory presented in this paper considers constraints on the maximum achievable speed and acceleration of the shadower. Our theory is tested through Matlab simulations, which validate the camouflage strategy for both 2D and 3D conditions. Furthermore, experiments using a realistic vision-based implementation are conducted in a virtual environment, where the results demonstrate that even with noisy state information it is possible to remain well camouflaged using the constant distance motion camouflage technique.

Evaluation of the Intel Xeon Phi 7120 and NVIDIA K80 as accelerators for two-dimensional panel codes

To optimize the geometry of airfoils for a specific application is an important engineering problem. In this context genetic algorithms have enjoyed some success as they are able to explore the search space without getting stuck in local optima. However, these algorithms require the computation of aerodynamic properties for a significant number of airfoil geometries. Consequently, for low-speed aerodynamics, panel methods are most often used as the inner solver. In this paper we evaluate the performance of such an optimization algorithm on modern accelerators (more specifically, the Intel Xeon Phi 7120 and the NVIDIA K80). For that purpose, we have implemented an optimized version of the algorithm on the CPU and Xeon Phi (based on OpenMP, vectorization, and the Intel MKL library) and on the GPU (based on CUDA and the MAGMA library). We present timing results for all codes and discuss the similarities and differences between the three implementations. Overall, we observe a speedup of approximately 2.5 for adding an Intel Xeon Phi 7120 to a dual socket workstation and a speedup between 3.4 and 3.8 for adding a NVIDIA K80 to a dual socket workstation.

Flow separation on flapping and rotating profiles with spanwise gradients

The growth of leading-edge vortices (LEV) on analogous flapping and rotating profiles has been investigated experimentally. Three time-varying cases were considered: a two-dimensional reference case with a spanwise-uniform angle-of-attack variation α; a case with increasing α towards the profile tip (similar to flapping flyers); and a case with increasing α towards the profile root (similar to rotor blades experiencing an axial gust). It has been shown that the time-varying spanwise angle-of-attack gradient produces a vorticity gradient, which, in combination with spanwise flow, results in a redistribution of circulation along the profile. Specifically, when replicating the angle-of-attack gradient characteristic of a rotor experiencing an axial gust, the spanwise-vorticity gradient is aligned such that circulation increases within the measurement domain. This in turn increases the local LEV growth rate, which is suggestive of force augmentation on the blade. Reversing the relative alignment of the spanwise-vorticity gradient and spanwise flow, thereby replicating that arrangement found in a flapping flyer, was found to reduce local circulation. From this, we can conclude that spanwise flow can be arranged to vary LEV growth to prolong lift augmentation and reduce the unsteadiness of cyclic loads.

Rise in Landing-Related Skydiving Fatalities

The purpose was to assess whether adoption of potentially dangerous skydiving gear and skydiving practices has led to an increase in fatalities. Beginning in the early 1990s, civilian skydivers began to utilize high performance parachutes that fly much faster and are much more responsive than older style parachutes. Also, skydivers began to fly these parachutes in a more aggressive manner. An analysis of data from the 507 skydiving fatalities in the USA between 1986 and 2001 indicated that this shift toward high performance parachutes and aggressive flying techniques was temporally associated with an increase in parachute-landing deaths. During the same time period, the total number of fatalities remained fairly stable.

Attentional costs and failures in air traffic control notifications

Large display screens are common in supervisory tasks, meaning that alerts are often perceived in peripheral vision. Five air traffic control notification designs were evaluated in their ability to capture attention during an ongoing supervisory task, as well as their impact on the primary task. A range of performance measures, eye-tracking and subjective reports showed that colour, even animated, was less effective than movement, and notifications sometimes went unnoticed. Designs that drew attention to the notified aircraft by a pulsating box, concentric circles or the opacity of the background resulted in faster perception and no missed notifications. However, the latter two designs were intrusive and impaired primary task performance, while the simpler animated box captured attention without an overhead cognitive cost. These results highlight the need for a holistic approach to evaluation, achieving a balance between the benefits for one aspect of performance against the potential costs for another. Practitioner summary: We performed a holistic examination of air traffic control notification designs regarding their ability to capture attention during an ongoing supervisory task. The combination of performance, eye-tracking and subjective measurements demonstrated that the best design achieved a balance between attentional power and the overhead cognitive cost to primary task performance.

Exerted pressure by an in-flight oxygen mask

BACKGROUND

F-16 pilots wear an in-flight oxygen mask to prevent hypoxemia. In the contact area with the mask, the pilots experience nasal discomfort and pain, and may even develop nasal deformities. A likely cause is the pressure exerted by the mask. In this study the hypothesis was that the change in pressure exerted on the nose would be higher than on the chin, an area free of symptoms.

METHODS

Six F-16 pilots and five healthy former F-16 pilots volunteered to participate in this observational pilot study. At baseline the pilots donned mask and helmet. The median delta pressure (deltap) recordings at baseline were compared to the exerted deltap during the experimental head movements.

RESULTS

At baseline, there was no significant difference between the median deltap on the nose and chin (2 vs. 1.6 mmHg, T = 2). Head movements increased the median deltap on the nose by 50 mmHg (T = 0) and on the chin by 31 mmHg (T = 0) when compared to baseline. Head movements also decreased the pressure by -20 mmHg (T = 1.75) on the nose and -11 mmHg (T = 0) on the chin.

CONCLUSIONS

The data show that the baseline deltap is higher on the nose than on the chin. The head movements both increased and decreased the exerted pressure on the nose and the chin. These observations suggest that further evaluation of the effect of flight conditions on the exerted pressure is worthwhile to understand its contribution to the nasal symptoms.

Testing usability and trainability of indirect touch interaction: perspective for the next generation of air traffic control systems

This study aims to determine whether indirect touch device can be used to interact with graphical objects displayed on another screen in an air traffic control (ATC) context. The introduction of such a device likely requires an adaptation of the sensory-motor system. The operator has to simultaneously perform movements on the horizontal plane while assessing them on the vertical plane. Thirty-six right-handed participants performed movement training with either constant or variable practice and with or without visual feedback of the displacement of their actions. Participants then performed a test phase without visual feedback. Performance improved in both practice conditions, but accuracy was higher with visual feedback. During the test phase, movement time was longer for those who had practiced with feedback, suggesting an element of dependency. However, this 'cost' of feedback did not extend to movement accuracy. Finally, participants who had received variable training performed better in the test phase, but accuracy was still unsatisfactory. We conclude that continuous visual feedback on the stylus position is necessary if tablets are to be introduced in ATC.

Cockpit displays of traffic information and pilot bias in time-to-contact judgments

INTRODUCTION

Pilots are susceptible to over-reliance on distance when making relative time-to-contact (TTC) judgments of surrounding intruders, referred to as "the distance bias." We tested the effect of adding perceptual cues and an information feature to cockpit displays of traffic information to mitigate this bias.

METHOD

There were 14 general aviation pilots who participated in a simulated flight scenario and were asked to make relative TTC judgments. Three levels of perceptual cue (blinking, color-change, and no-cue) were crossed with two levels of velocity data tag (present and absent) with identification of the highest risk intruder as a response.

RESULTS

Perceptual cues were associated with more accurate high-risk intruder selection (color = 95.95% correct, blinking = 95.98%, no-cue = 87.89%), decreased response time (color = 3.68 s, blinking = 3.19 s, no-cue = 6.08 s), reduced visual attention demand (color = 57% of attention, blinking = 58%, no-cue = 62%), lower workload ratings (color = 28.38/100, blinking = 29.66/100, no-cue = 48.91/100), and higher performance confidence ratings (color = 83.92/100, blinking = 82.71/100, no-cue = 58.85/100) than the no-cue displays. There was no difference between blinking and color cue displays. The data tag was associated with lower response times (present = 4.13 s, absent = 4.50 s) and higher confidence ratings (present = 78.69/100, absent = 71.63/100) than displays without. Displays including the blinking cue, color-change cue, and data tag were preferred over displays that did not include these features (color = 8 pilots, blinking = 6, no-cue = 0).

DISCUSSION

The added display features were effective in mitigating the effect of the distance bias on pilot performance measures and received favorable subjective ratings.

Composition and morphology of particle emissions from in-use aircraft during takeoff and landing

In order to provide realistic data for air pollution inventories and source apportionment at airports, the morphology and composition of ultrafine particles (UFP) in aircraft engine exhaust were measured and characterized. For this purpose, two independent measurement techniques were employed to collect emissions during normal takeoff and landing operations at Brisbane Airport, Australia. PM1 emissions in the airfield were collected on filters and analyzed using the particle-induced X-ray emission (PIXE) technique. Morphological and compositional analyses of individual ultrafine particles in aircraft plumes were performed on silicon nitride membrane grids using transmission electron microscopy (TEM) combined with energy-dispersive X-ray microanalysis (EDX). TEM results showed that the deposited particles were in the range of 5-100 nm in diameter, had semisolid spherical shapes and were dominant in the nucleation mode (18-20 nm). The EDX analysis showed the main elements in the nucleation particles were C, O, S, and Cl. The PIXE analysis of the airfield samples was generally in agreement with the EDX in detecting S, Cl, K, Fe, and Si in the particles. The results of this study provide important scientific information on the toxicity of aircraft exhaust and their impact on local air quality.

Ozone and ozone byproducts in the cabins of commercial aircraft

The aircraft cabin represents a unique indoor environment due to its high surface-to-volume ratio, high occupant density, and the potential for high ozone concentrations at cruising altitudes. Ozone was continuously measured and air was sampled on sorbent traps, targeting carbonyl compounds, on 52 transcontinental U.S. or international flights between 2008 and 2010. The sampling was predominantly on planes that did not have ozone scrubbers (catalytic converters). Peak ozone levels on aircraft without catalytic convertors exceeded 100 ppb, with some flights having periods of more than an hour when the ozone levels were >75 ppb. Ozone was greatly reduced on relatively new aircraft with catalytic convertors, but ozone levels on two flights whose aircraft had older convertors were similar to those on planes without catalytic convertors. Hexanal, heptanal, octanal, nonanal, decanal, and 6-methyl-5-hepten-2-one (6-MHO) were detected in the aircraft cabin at sub- to low ppb levels. Linear regression models that included the log transformed mean ozone concentration, percent occupancy, and plane type were statistically significant and explained between 18 and 25% of the variance in the mixing ratio of these carbonyls. Occupancy was also a significant factor for 6-MHO, but not the linear aldehydes, consistent with 6-MHO's formation from the reaction between ozone and squalene, which is present in human skin oils.

To twist, roll, stroke or poke? A study of input devices for menu navigation in the cockpit

Modern interfaces within the aircraft cockpit integrate many flight management system (FMS) functions into a single system. The success of a user's interaction with an interface depends upon the optimisation between the input device, tasks and environment within which the system is used. In this study, four input devices were evaluated using a range of Human Factors methods, in order to assess aspects of usability including task interaction times, error rates, workload, subjective usability and physical discomfort. The performance of the four input devices was compared using a holistic approach and the findings showed that no single input device produced consistently high performance scores across all of the variables evaluated. The touch screen produced the highest number of 'best' scores; however, discomfort ratings for this device were high, suggesting that it is not an ideal solution as both physical and cognitive aspects of performance must be accounted for in design.

PRACTITIONER SUMMARY

This study evaluated four input devices for control of a screen-based flight management system. A holistic approach was used to evaluate both cognitive and physical performance. Performance varied across the dependent variables and between the devices; however, the touch screen produced the largest number of 'best' scores.

Evaluation of head-free eye tracking as an input device for air traffic control

The purpose of this study was to investigate the possibility to integrate a free head motion eye-tracking system as input device in air traffic control (ATC) activity. Sixteen participants used an eye tracker to select targets displayed on a screen as quickly and accurately as possible. We assessed the impact of the presence of visual feedback about gaze position and the method of target selection on selection performance under different difficulty levels induced by variations in target size and target-to-target separation. We tend to consider that the combined use of gaze dwell-time selection and continuous eye-gaze feedback was the best condition as it suits naturally with gaze displacement over the ATC display and free the hands of the controller, despite a small cost in terms of selection speed. In addition, target size had a greater impact on accuracy and selection time than target distance. These findings provide guidelines on possible further implementation of eye tracking in ATC everyday activity.

PRACTITIONER SUMMARY

We investigated the possibility to integrate a free head motion eye-tracking system as input device in air traffic control (ATC). We found that the combined use of gaze dwell-time selection and continuous eye-gaze feedback allowed the best performance and that target size had a greater impact on performance than target distance.

Occupational and public field exposure from communication, navigation, and radar systems used for air traffic control

Electromagnetic exposure (occupational and general public) to 14 types of air traffic control (ATC) systems is assessed. Measurement methods are proposed for in situ exposure assessment of these ATC systems. In total, 50 sites are investigated at 1,073 locations in the frequency range of 255 kHz to 24 GHz. For all installations, typical and maximal exposure values for workers and the general public are provided. Two of the 14 types of systems, Non-Directional Beacons (NDB) (up to 881.6 V m) and Doppler Very High Frequency (VHF) Omni-directional Range (DVOR) (up to 92.3 V m), exhibited levels requiring recommended minimum distances such that the ICNIRP reference levels are not exceeded. Cumulative exposure of all present radiofrequency (RF) sources is investigated, and it is concluded that the ATC source dominates the total exposure in its neighborhood.

In situ occupational and general public exposure to VHF/UHF transmission for air traffic communication

Occupational and general public exposure due to very high frequency (VHF)/ultra high frequency (UHF) transmission centres for verbal communication for air traffic control is investigated in situ for the first time. These systems are used for communication with aircraft, resulting in different human exposure from that of classical broadcasting. Measurement methods are proposed for the exposure assessment, and a measurement campaign is executed in three transmission centres. By investigating the temporal behaviour of the VHF signals for 6 d, a realistic worst-case duty cycle of 29 % is determined. Periods of high exposures corresponding with high aircraft traffic are from 7 a.m. to 1 p.m. and in the evening. All measured electric-field values satisfy the International Commission on Non-ionizing Radiation Protection guidelines. Fields vary from 0.2 to 21.1 V m(-1) for occupational exposure and from 0.007 to 8.0 V m(-1) for general public exposure. The average fields equal 5.2 V m(-1) for workers, and 0.7 V m(-1) for general public.

Vessel motion thresholds for maintaining physical and cognitive performance: a study of naval personnel at sea

Methods and results are reported from a study of ships companies' exposure to low-frequency motions on three vessels of the Royal Navy. The aim of the study was to investigate relationships between deck accelerations and the incidence of problems such as difficulties with physical tasks, cognitive activities, motion sickness, and work effort. Ship motions were recorded continuously during sea patrols of 10-14 days. The data collected from the three vessels comprised 105 days of ship motions over 12 patrols, with 779 associated daily diaries from 78 participants. Problems most strongly associated with vessel motions were related to the difficulties with physical tasks. Some cognitive aspects of task performance and motion sickness were associated with vertical acceleration magnitudes, but the correlations were less strong than with physical tasks. Practitioner Summary: Little is known about the severity of ship motions that degrade physical and mental performance. The paper offers preliminary estimates of the motion threshold values below which the performance will not be degraded by motion.

[Means and methods of acoustic protection in aviation: current status and outlook for development]

Analysis of the current status of acoustic protection in aviation shows that despite the material progress in the field, risk of professional pathologies in flying and technical personnel is still high. The situation is dramatized by the lack of effective personal and crew acoustic protectors. The authors speculate on applicability of innovative materials and technologies, ingenious designs of earphones and modular prefabricated demountable structures. Tests of proposed personal protectors demonstrated their competitiveness with foreign analogs. Prospective lines of development, e.g. incorporation of active sound absorption systems in existing passive protectors are discussed.

Vibrotactile "on-thigh" alerting system in the cockpit

BACKGROUND

Alerts in the cockpit must be robust, difficult to ignore, and easily recognized. Tactile alerts can provide means to direct the pilot's attention in the already visual-auditory overloaded cockpit environment.

OBJECTIVE

This research examined the thigh as a placement for vibrotactile display in the cockpit. The authors (a) report initial findings concerning the loci and properties of the display, (b) evaluate the added value of tactile cuing with respect to the existing audiovisual alerting system, and (c) address the issue of tactile orienting--whether the cue should display "flight" or "fight" orienting. The tactor display prototype was developed by a joint venture of Israel Aerospace Industries, Lahav Division, and the Ben Gurion University of the Negev (patent pending 11/968,405). A vibrotactile display mounted on the thigh provided directional cues in the vertical plane. Two vibrotactile display modes (eight and four tactors) and two response modes (compatible, i.e., fight [toward vibrotactile cue], and inverse, i.e., flight [away from vibrotactile cue]) were evaluated.

RESULTS

Vertical directional orienting can be achieved by a vibrotactile display assembled on the thigh. The four-tactor display mode and the compatible response mode produced more accurate results.

CONCLUSION

Tactile cues can provide directional orienting in the vertical plane. The benefit of adding compatible tactile cues compared with visual and auditory cues alone has yet to be reinforced. Nevertheless, fight mode, that is, directing the way to escape from hazardous situations, was preferred.

APPLICATION

Potential applications include providing directional collision alerts within the vertical plane, assisting pilot's elevation control, or navigation.

From crisis to development--analysis of air traffic control work processes

In this study an intervention to improve work processes in air traffic control (ATC) is evaluated. The background was the Finnish air traffic controllers' strike of 1999. The old ways of thinking and acting did not support development of ATC prompting a need for a new kind of working culture in the organisation. Several actions were started. In one of these, ATC work processes were modelled by personnel and development plans concerning work were delivered to top management. Different actors (management, trade union, stakeholders) were interviewed before (n=16) and after the project (n=7). The intervention supported systematic co-operation between different actors in the organisation. However, a follow-up revealed that only a few participants had adopted the idea of continuous work development. Mastery of human factors is crucial in a high reliability work environment such as ATC. But how is the analytical and co-operative aspect kept alive in an organisation that is run by strict international regulation and has a strong technical competence, but is not that strong in collaborative and human aspects?

Tailoring mechanical properties of aerogels for aerospace applications

Silica aerogels are highly porous solid materials consisting of three-dimensional networks of silica particles and are typically obtained by removing the liquid in silica gels under supercritical conditions. Several unique attributes such as extremely low thermal conductivity and low density make silica aerogels excellent candidates in the quest for thermal insulation materials used in space missions. However, native silica aerogels are fragile at relatively low stresses. More durable aerogels with higher strength and stiffness are obtained by proper selection of silane precursors and by reinforcement with polymers. This paper first presents a brief review of the literature on methods of silica aerogel reinforcement and then discusses our recent activities in improving not only the strength but also the elastic response of polymer-reinforced silica aerogels. Several alkyl-linked bis-silanes were used in promoting flexibility of the silica networks in conjunction with polymer reinforcement by epoxy.

Military static line parachuting injuries seen by the airborne battalion provider

Military static line parachuting exposes jumpers to a variety of novel methods of injury. Providers assigned to Airborne units need to develop and maintain a high index of suspicion when dealing with jump-related injuries. Understanding the incident rate and the mechanism of injury can help a provider better identify injuries based on the history of the incidence and develop that index of suspicion. Injuries can happen at almost any point during the jump process and each step has both common and unique injuries associated with it. In addition to identifying, managing, and treating the injuries involved, providing information on estimated time until return to duty can be beneficial for the commander. In the end, a provider's best tools for managing Airborne-related injuries are an understanding of Airborne operations, quality orthopedic skills, and a high index of suspicion.

A flexible strain sensor based on a Conductive Polymer Composite for in situ measurement of parachute canopy deformation

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%.

Injury profile for airborne operations utilizing the SF-10A maneuverable parachute

PURPOSE

The purpose of this investigation was to determine the injury profile of the steerable, SF-10A, static-line parachute.

METHODS

The investigation evaluated prospectively 972 low-level static-line training jumps for major injuries that required CASEVAC from the drop zone and for minor injuries that allowed the jumpers to continue with their training mission.

RESULTS

The investigation found overall injury rates to be 8.23 per 1000 jumps, with 2.03 per 1000 jumps requiring CASEVAC.

CONCLUSIONS

Overall attrition rates of the steerable SF-10A parachute were below those of previously reported non-steerable parachutes, suggesting further evaluation is warranted of maneuverable parachutes in all military services.

Scapula fracture secondary to static line injury in a 22 year-old active duty soldier

This radiological case study of scapula fracture is reported in a 22 year-old active duty male Soldier who sustained a static line injury during an airborne operation at Fort Bragg, North Carolina. This is the first reported scapula fracture secondary to this mechanism since a 1973 report by Heckman and Levine. The fracture was neither identified by Emergency Department nor Orthopedic Surgery providers, and was reported in the radiologist?s formal read. Ten emergency physicians and emergency medicine physician assistants reviewed the radiographical studies and none successfully identified the injury. Because this injury was uniformly missed by experienced emergency medicine providers it is presented as a radiographic case study in hopes that this injury will not go undiagnosed, potentially causing increased morbidity and mortality in this patient population. The patient was treated with a posterior splint and immobilization and seen by the orthopedic service the next day. Interestingly, the orthopedic surgeon also did not recognize this fracture. This mechanism of injury is rarely seen in clinical practice outside of the airborne community. Scapula fractures can be an indicator of serious thoracic trauma and may prompt the need for further diagnostic studies. The fact that so many providers missed the injury reinforces the need to evaluate the patient as a whole and to be ever suspicious of missing concomitant injuries in the trauma patient.

False alerts in air traffic control conflict alerting system: is there a "cry wolf" effect?

OBJECTIVE

The aim is to establish the extent to which the high false-alarm rate of air traffic control midair conflict alerts is responsible for a "cry wolf' effect-where true alerts are not responded to and all alerts are delayed in their response.

BACKGROUND

Some aircraft collisions have been partly attributed to the cry wolf effect, and in other domains (health care and systems monitoring), there is a causal connection between false-alarm rate and cry wolf behavior. We hypothesized that a corresponding relationship exists in air traffic control (ATC).

METHOD

Aircraft track and alert system behavior data surrounding 495 conflict alerts were analyzed to identify true and false alerts, trajectory type, and controller behavior. Forty-five percent of the alerts were false, ranging from 0.28 to 0.58.

RESULTS

Although centers with more false alerts contributed to more nonresponses, there was no evidence that these were nonresponses to true alerts or that response times were delayed in those centers. Instead, controllers showed desirable anticipatory behavior by issuing trajectory changes prior to the alert. Those trajectory pairs whose conflicts were more difficult to visualize induced more reliance on, and less compliance with, the alerting system.

CONCLUSION

The high false-alarm rate does not appear to induce cry wolf behavior in the context of en route ATC conflict alerts.

APPLICATION

There is no need to substantially modify conflict alert algorithms, but the conflict alert system may be modified to address difficult-to-visualize conflicts.

Catalytic microtubular jet engines self-propelled by accumulated gas bubbles

Strain-engineered microtubes with an inner catalytic surface serve as self-propelled microjet engines with speeds of up to approximately 2 mm s(-1) (approximately 50 body lengths per second). The motion of the microjets is caused by gas bubbles ejecting from one opening of the tube, and the velocity can be well approximated by the product of the bubble radius and the bubble ejection frequency. Trajectories of various different geometries are well visualized by long microbubble tails. If a magnetic layer is integrated into the wall of the microjet engine, we can control and localize the trajectories by applying external rotating magnetic fields. Fluid (i.e., fuel) pumping through the microtubes is revealed and directly clarifies the working principle of the catalytic microjet engines.

Viewpoint animation with a dynamic tether for supporting navigation in a virtual environment

OBJECTIVE

This study examined the concept of dynamic viewpoint tethering for enhancing performance in 3-D avatar control tasks.

BACKGROUND

Dynamic viewpoint tethering refers to a viewpoint animation technique that couples a display viewpoint to a controlled avatar through a virtual tether. A dynamic tether, modeled as a mass spring damper system, can potentially generate desirable viewpoint behavior because of its ability to produce frequency-separated viewpoint responses. This study investigated the impact of a tether's rigidity and damping properties on users' navigational performance.

METHODS

Twelve participants took part in a simulated 3-D aerial navigational task. Performance was evaluated with respect to local guidance and global awareness.

RESULTS

Root mean square error scores revealed a decrease in local guidance performance when (a) the tether was either severely underdamped or overdamped and (b) the tether's rigidity approached either zero or infinity. In addition, (c) global performance was better for higher-frequency forcing functions.

CONCLUSION

Critical damping and medium rigidity can be optimized during design for enhancing users' navigational efficiency.

APPLICATION

Guidelines generated from this study support future viewpoint design in interactive virtual reality applications.

Display dimensionality and conflict geometry effects on maneuver preferences for resolving in-flight conflicts

OBJECTIVE

Two experiments explored the effects of display dimensionality, conflict geometry, and time pressure on pilot maneuvering preferences for resolving en route conflicts.

BACKGROUND

With the presence of a cockpit display of traffic information (CDTI) that provides graphical airspace information, pilots can use a variety of conflict resolution maneuvers in response to how they perceive the conflict. Inconsistent preference findings from previous research on conflict resolution using CDTIs may be attributable to inherent ambiguities in 3-D perspective displays and/or a limited range of conflict geometries.

METHODS

Pilots resolved predicted conflicts using CDTIs with three levels of display dimensionality; the first had two 2-D orthogonal views, the second depicted the airspace in two alternating 3-D perspective views, and the third had a pilot-controlled swiveling viewpoint.

RESULTS

Pilots demonstrated the same preferences that have been observed in previous research for vertical over lateral maneuvers in low workload and climbs over descents for level-flight conflicts. With increasing workload the two 3-D perspective displays, but not the 2-D displays, resulted in an increased preference for lateral over vertical maneuvers. Increased time pressure resulted in increased vertical maneuvers, an effect again limited to the two 3-D perspective displays.

CONCLUSION

Resolution preferences were more affected by workload and time pressure when the 3-D perspective displays were used, as compared with the 2-D displays, although overall preferences were milder than in previous studies.

APPLICATION

Investigating maneuver preferences using the strategic flight planning paradigm employed in this study may be the key to better ensure pilot acceptance of computer-generated resolution maneuvers.

Testing a multidimensional nonveridical aircraft collision avoidance system

OBJECTIVE

This study explores operators' ability to use a multidimensional, nonveridical control display.

BACKGROUND

Veridical displays represent realistic scenes. State space displays represent nonveridical n-dimensional information based on informative coordinate axes plus variable features such as color and shading. Empirical investigation of state space displays is relatively new to human factors research.

METHOD

Twelve licensed general aviation pilots flew flight scenarios, trying to deviate as little as possible from a preassigned course while still maintaining standard en route separation from traffic. Flight performance using only a veridical cockpit display of traffic information (CDTI) was compared with performance using the CDTI augmented by a 4-D nonveridical state space collision avoidance system (CDTI+4CAS).

RESULTS

Using moderate traffic density and complex traffic geometry, the CDTI+4CAS condition showed performance superiority over the baseline CDTI-only condition for five of five dependent measures of maneuver efficiency, four of four measures of maneuver safety, and six of nine measures of user workload.

CONCLUSION

Results suggest that nonveridical information display may enhance operator performance on a control task involving simultaneous processing of multidimensional information.

APPLICATION

Nonveridical information displays have potential application wherever human control of multidimensional processes is involved.

Visual misperception in aviation: glide path performance in a black hole environment

OBJECTIVE

We sought to improve understanding of visual perception in aviation to mitigate mishaps in approaches to landing.

BACKGROUND

Research has attempted to identify the most salient visual cues for glide path performance in impoverished visual conditions. Numerous aviation accidents caused by glide path overestimation (GPO) have occurred when a low glide path was induced by a black hole illusion (BHI) in featureless terrain during night approaches.

METHOD

Twenty pilots flew simulated approaches under various visual cues of random terrain objects and approach lighting system (ALS) configurations. Performance was assessed relative to the desired 3 degrees glide path in terms of precision, bias, and stability.

RESULTS

With the high-ratio (long, narrow) runway, the overall performance between 8.3 and 0.9 km from the runway depicted a concave approach shape found in BHI mishaps. The addition of random terrain objects failed to improve glide path performance, and an ALS commonly used at airports induced GPO and the resulting low glide path. The worst performance, however, resulted from a combination ALS consisting of both side and approach lights. Surprisingly, novice pilots flew more stable approaches than did experienced pilots.

CONCLUSIONS

Low, unsafe approaches occur frequently in conditions with limited global and local visual cues. Approach lights lateral of the runway may counter the bias of the BHI. The variability suggested a proactive, cue-seeking behavior among experienced pilots as compared with novice pilots.

APPLICATION

Visual spatial disorientation training in flight simulators should be used to demonstrate visual misperceptions in black hole environments and reduce pilots' confidence in their limited visual capabilities.

Tactile cueing effects on performance in simulated aerial combat with high acceleration

INTRODUCTION

Recent evidence indicates that vibrotactile displays can potentially reduce the risk of sensory and cognitive overload. Before these displays can be introduced in super agile aircraft, it must be ascertained that vibratory stimuli can be sensed and interpreted by pilots subjected to high G loads.

METHODS

Each of 9 pilots intercepted 32 targets in the Swedish Dynamic Flight Simulator. Targets were indicated on simulated standard Gripen visual displays. In addition, in half of the trials target direction was also displayed on a 60-element tactile torso display. Performance measures and subjective ratings were recorded.

RESULTS

Each pilot pulled G peaks above +8 Gz. With tactile cueing present, mean reaction time was reduced from 1458 ms (SE = 54) to 1245 ms (SE = 88). Mean total chase time for targets that popped up behind the pilot's aircraft was reduced from 13 s (SE = 0.45) to 12 s (SE = 0.41). Pilots rated the tactile display favorably over the visual displays at target pop-up on the easiness of detecting a threat presence and on the clarity of initial position of the threats.

DISCUSSION

This study is the first to show that tactile display information is perceivable and useful in hypergravity (up to +9 Gz). The results show that the tactile display can capture attention at threat pop-up and improve threat awareness for threats in the back, even in the presence of high-end visual displays. It is expected that the added value of tactile displays may further increase after formal training and in situations of unexpected target pop-up.

The future of scientific ballooning

This paper gives a brief overview of the historical development of scientific balloons and their capabilities. Furthermore, a recent programme by NASA is introduced that aims to develop balloons capable of carrying payloads of several tonnes to above 99% of the Earth's atmosphere for up to 100 days. It is shown that the currently investigated balloons suffer from instabilities that can be minimized using a different design paradigm for the cutting patterns. Finally, a novel balloon design, similar to the topology of radiolarians, is introduced that is potentially superior to existing designs.

Dual-task performance consequences of imperfect alerting associated with a cockpit display of traffic information

OBJECTIVE

Performance consequences related to integrating an imperfect alert within a complex task domain were examined in two experiments.

BACKGROUND

Cockpit displays of traffic information (CDTIs) are being designed for use in airplane cockpits as responsibility for safe separation becomes shared between pilots and controllers. Of interest in this work is how characteristics of the alarm system such as threshold, modality, and number of alert levels impact concurrent task (flight control) performance and response to potential conflicts.

METHODS

Student pilots performed a tracking task analogous to flight control while simultaneously monitoring for air traffic conflicts with the aid of a CDTI alert as the threshold, modality, and level of alert was varied.

RESULTS

As the alerting system became more prone to false alerts, pilot compliance decreased and concurrent performance improved. There was some evidence of auditory preemption with auditory alerts as the false alarm rate increased. Finally, there was no benefit to a three-level system over a two-level system.

CONCLUSION

There is justification for increased false alarm rates, as miss-prone systems appear to be costly. The 4:1 false alarm to miss ratio employed here improved accuracy and concurrent task performance. More research needs to address the potential benefits of likelihood alerting.

APPLICATION

The issues addressed in this research can be applied to any imperfect alerting system such as in aviation, driving, or air traffic control. It is crucial to understand the performance consequences of new technology and the efficacy of potential mitigating design features within the specific context desired.

Pilot performance, strategy, and workload while executing approaches at steep angles and with lower landing minima

OBJECTIVE

We examined the willingness and ability of general aviation pilots to execute steep approaches in low-visibility conditions into nontowered airports.

BACKGROUND

Executing steep approaches in poor weather is required for a proposed Small Aircraft Transportation System (SATS) that consists of small aircraft flying direct routes to a network of regional airports.

METHOD

Across two experiments, 17 pilots rated for Instrument Flight Rules at George Mason University or Virginia Tech flew a Cessna 172R simulator into Blacksburg, Virginia. Pilots were familiarized with the simulator and asked to fly approaches with either a 200- or 400-foot ceiling (at approach angles of 3 degrees, 5 degrees, and 7 degrees in the first experiment, 3 degrees and 6 degrees in the second). Pilots rated subjective workload and the simulator recorded flight parameters for each set of approaches.

RESULTS

Approaches with a 5 degree approach angle produced safe landings with minimal deviations from normal descent control configurations and were rated as having a moderate level of workload. Approaches with 6 degree and 7 degree approach angles produced safe landings but high workload ratings. Pilots reduced power to control the speed of descent and flew the aircraft slightly above the glide path to gain time to control the landing.

CONCLUSION

Although the 6 degree and 7 degree approaches may not be practical for routine approaches, they may be achievable in the event of an emergency.

APPLICATION

Further work using other aircraft flying under a wider variety of conditions is needed before implementing SATS-type flights into airports intended to supplant or complement commercial operations in larger airports.

Endovascular management of a thoracic aortic disruption following failure of deployment of a parachute

Traumatic thoracic aortic disruption is a life-threatening lesion associated with a high surgical mortality. Endovascular stent graft repair is a minimal invasive approach that does not require a thoracotomy, aortic cross clamping and cardiopulmonary bypass. We report the use of an endoluminal graft to treat a 58-year-old male, who sustained multiple injuries including thoracic aortic disruption in a sky-diving accident due to failure of deployment of his parachute.