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.

What you don't know can hurt you: factors impacting diagnosis in the automated cockpit

OBJECTIVE

We examined the impact of operational variables on diagnosis and decision-making processes, focusing on information search.

BACKGROUND

Arguably, the "best" decision-making processes in high-technology cockpits would be those that are both correspondent (objectively accurate) and coherent (rationally sound). In the electronic world, coherence in terms of identification and incorporation of all relevant information is both a prerequisite to and a limiting factor for accurate diagnosis and decision making.

METHOD

Regional carrier pilots (N=93) responded to six scenarios by accessing information to determine a diagnosis and decision.

RESULTS

Time pressure, a common operational variable, had a strong negative effect on information search and diagnosis accuracy, and the presence of noncongruent information heightened these negative effects. Unexpectedly, source of initial information (automated or other) did not impact any of the dependent variables. Diagnosis confidence was unrelated to accuracy and was negatively related to amount of information accessed.

CONCLUSION

Results confirm both the need for coherence in diagnostic processes and the difficulty of maintaining it under time pressure.

APPLICATION

One implication of the results of this study is that pilots in high-technology cockpits must be trained to utilize coherent diagnostic processes as standard operating procedure. Additionally, because thorough information search for diagnosis in an automated environment is essential, automated systems must be designed to foster coherent, and thus accurate, diagnostic processes.

Effects of imperfect automation on decision making in a simulated command and control task

OBJECTIVE

Effects of four types of automation support and two levels of automation reliability were examined. The objective was to examine the differential impact of information and decision automation and to investigate the costs of automation unreliability.

BACKGROUND

Research has shown that imperfect automation can lead to differential effects of stages and levels of automation on human performance.

METHOD

Eighteen participants performed a "sensor to shooter" targeting simulation of command and control. Dependent variables included accuracy and response time of target engagement decisions, secondary task performance, and subjective ratings of mental work-load, trust, and self-confidence.

RESULTS

Compared with manual performance, reliable automation significantly reduced decision times. Unreliable automation led to greater cost in decision-making accuracy under the higher automation reliability condition for three different forms of decision automation relative to information automation. At low automation reliability, however, there was a cost in performance for both information and decision automation.

CONCLUSION

The results are consistent with a model of human-automation interaction that requires evaluation of the different stages of information processing to which automation support can be applied.

APPLICATION

If fully reliable decision automation cannot be guaranteed, designers should provide users with information automation support or other tools that allow for inspection and analysis of raw data.

Effects of conflict alerting system reliability and task difficulty on pilots' conflict detection with cockpit display of traffic information

A total of 24 pilots viewed dynamic encounters between their own aircraft and an intruder aircraft on a 2-D cockpit display of traffic information (CDTI) and estimated the point and time of closest approach. A three-level alerting system provided a correct categorical estimate of the projected miss distance on 83% of the trials. The remaining 17% of alerts were equally divided between misses and false alarms, of large and small magnitude. Roughly half the pilots depended on automation to improve estimation of miss distance relative to the baseline pilots, who viewed identical trials without the aid of automated alerts. Moreover, they did so more on the more difficult traffic trials resulting in improved performance on the 83% correct automation trials without causing harm on the 17% automation-error trials, compared to the baseline group. The automated alerts appeared to lead pilots to inspect the raw data more closely. While assisting the accurate prediction of miss distance, the automation led to an underestimate of the time remaining until the point of closest approach. The results point to the benefits of even imperfect automation in the strategic alerts characteristic of the CDTI, at least as long as this reliability remains high (above 80%).

Can color vision defective subjects who pass the farnsworth lantern test recognize surface color codes?

INTRODUCTION

The International Civil Aviation Organization requires that pilots be able to distinguish the colors used in air navigation and in particular be able to identify the colors of signal lights. Most national aviation authorities use a lantern test to assess the ability of applicants for a pilot's license who have abnormal color vision to recognize the colors of signal lights. However, color-coding is now widely used in aviation systems other than signal lights. Color is used in tarmac markings, maps, manuals, and electronic flight instrument displays. These color codes can use 10 or more colors, many more than the 3 to 5 used for signal lights. This study investigated whether people with defective color vision (DCV) who pass the Farnsworth lantern test can recognize the main colors used for surface color codes.

METHODS

There were 99 subjects with DCV who were tested using the Optec 900 version of the Farnsworth lantern test and also named the colors of a set of 10 surface colors that varied in shape (dots and lines) and size (3 sizes; angular diameters 0.27, 1.0, and 2.4 degrees; angular widths 0.14, 0.27, and 0.50 degrees). A control group of 20 subjects with normal color vision also named the surface colors.

RESULTS

Of the DCV subjects, 19% passed the Farnsworth lantern test, of whom 74% made no errors with the surface colors. The other 26% made few errors (up to 5 errors in 120 presentations) and those errors were mostly to confuse red, orange, and brown. The subjects with normal color vision made no errors naming the surface colors.

CONCLUSION

Those who pass the Farnsworth lantern test can recognize the colors of a 10-color surface color code with few or no errors. This is because the small (2.9-min arc) stimulus of the lantern test presents a more difficult task than the larger surface colors.

Injuries caused by parachute risers during foreign military parachuting

OBJECTIVE

The objective was to study the injuries from the deployment of military parachutes when parachuting with foreign armies.

METHODS

The number and nature of injuries sustained while military parachuting with domestic and foreign parachute systems and techniques was compared.

RESULTS

Of a total of 370 parachutists, 41 (11.1%) suffered minor injuries following two descents on the British parachute, 20 (5.4%) of these were classified as riser injuries. Thirty-eight (25.9%) of 147 British parachutists sustained riser injuries following two descents with the French parachute. Thirty-four (89.5%) of these injuries were minor posterior-auricular bruises and abrasions not requiring treatment. Four (10.5%) were extensive posterior-auricular abrasions that required treatment. Two soldiers (5.3%) suffered lacerations of the attachment of the pinna to the head. There were no riser injuries and no other injuries when the soldiers parachuted with their own countries parachutes in the proceeding two descents.

CONCLUSION

Failure to adhere to drills led to injuries with foreign parachute systems.

Oxygen delivery comparison of two constant-flow masks during flight to 6863 m

OBJECTIVE

Differences in mask design may alter the oxygen flow required to gain similar oxygenation at a particular altitude. The selection of the most efficient mask would be advantageous for general aviation and other applications where oxygen supply is limited.

METHODS

We compared a basic mask (BAS) without valves or oxygen reservoir bag to a test mask (TST) with three valves and a reservoir designed to deliver up to 80% oxygen for critically ill patients. Randomly assigned parachutists (n = 31) used the masks during a flight with a gradual climb to 6863 m (22,500 ft). The oxygen flow was individually controlled to produce oxygen saturation (SpO2) of 95-97% as determined by pulse oximetry. Oxygen flow and SpO2 were obtained every 305 m (1000 ft).

RESULTS

Baseline age, lung function indices, and SpO2 were comparable for the two groups. Mean in-flight Spo2 values were 95.3 +/- 0.5% for the BAS and 96.2 +/- 1.1 % for the TST, respectively. Above 3965 m (13,000 ft) the TST required significantly less oxygen flow than the BAS to maintain the target SpO2. At 6863 m (22,500 ft), mean oxygen flow was 5.5 +/- 3.5 L x min(-1) for the BAS vs. 3.4 +/- 2.3 L x min(-1) for the TST (p = 0.029). No adverse reactions were reported from either group.

CONCLUSION

The TST required significantly less oxygen flow compared with the BAS at high altitudes and may, therefore, reduce total oxygen use, resulting in reduced costs and longer oxygen availability during a flight.

Recovery from unusual attitudes: HUD vs. back-up display in a static F/A-18 simulator

OBJECTIVE

Spatial disorientation (SD) remains one of the most important causes of fatal fighter aircraft accidents. The aim of this study was to give a recommendation for the use of the head-up display (HUD) or back-up attitude directional indicator (ADI) in a state of spatial disorientation based on the respective performance in an unusual attitude recovery task.

METHODS

Seven fighter pilots joining a conversion course to the F/A-18 participated in this study. Flight time will be presented as range (and mean in parentheses). Total military flight experience of the subjects was 835-1759 h (1412 h). Flight time on the F/A-18 was 41-123 h (70 h). The study was performed in a fixed base F/A-18D Weapons Tactics Trainer. We tested the recovery from 11 unusual attitudes and analyzed decision time (DT), total recovery time (TRT), and error rates for the HUD or the back-up ADI.

RESULTS

We found no differences regarding either reaction times or error rates. For the HUD we found a DT (mean +/- SD) of 1.3 +/- 0.4 s, a TRT of 9.1 +/- 4.1 s, and an error rate of 29%. For the ADI the respective values were a DT of 1.4 +/- 0.4 s, a TRT of 8.3 +/- 3.8 s, and an error rate of 27%.

CONCLUSION

Unusual attitude recoveries are performed equally well using the HUD or the back-up ADI. Switching from one instrument to the other during recovery should be avoided since it would probably result in a loss of time without benefit.

Aviation signal light gun: variations in photometric and colorimetric properties among airports

PURPOSE

The aviation signal light gun (LG) is believed by some to be the only color-critical task in aviation without redundant coding. However, there are questions regarding its practicality as a test of color vision given that the brightness and colors may vary between airports.

METHODS

The chromaticity coordinates and relative intensities of five LGs were measured with a portable spectroradiometer. Four of the LGs were measured at airports in southern Ontario and compared with a newly purchased LG (ATI Avionics). The air traffic controllers (ATCs) were also surveyed regarding the frequency of LG use.

RESULTS

Only 40% of the LGs at the airports were in good working condition. All working LGs met the ICAO standards for airport signal lights. However, differences did exist between models which were related to the date of manufacture. Older LG lights were dimmer and their green and white lights were more yellow than the newer LGs. ATCs reported that they used the LG primarily for pilot instruction and demonstration. However, in two locations, the LG was used to signal pilots who were flying their aircraft in for radio repair. This occurred about once or twice a month.

DISCUSSION

The LG is used primarily for instructional purposes. However, if a radio repair shop is at the airport, then the LG will be used about once to twice a month. There is sufficient variability in the light colors and intensity across airports so that any given LG cannot be used as valid practical test of color vision in aviation.

Long-term measurements of H*(10) at aviation altitudes in the northern hemisphere

Monitoring the radiation field at aviation altitudes is achieved by the dosemeter system piDOS installed in a passenger aircraft. The basic detector is a 2 in. tissue-equivalent proportional counter (TEPC) mounted in a cabin-baggage-sized aluminium suitcase. The entire system was characterised in neutron and photon reference fields from which two calibration factors were determined according to the splitting of the measured dose deposition spectrum yd(y) into low-LET and high-LET regions. A total of 255 flights in the northern hemisphere was analysed. The dependencies of the ambient dose equivalent rates on altitude, latitude and solar activity have been determined. These new data extend the data base used in Germany for the validation of program codes to calculate the radiation exposure of air crew members.

[A new type of active noise cancellation earmuffs]

OBJECTIVE

To develop a new type of feedback active noise cancellation earmuff (ANCE) for aviator's helmet.

METHOD

A mathematical model of such a structure was established based on frequency response function and automatic control theory. The method and role for designing ANCE controllers were summarized and the optimum design method was used for designing the controllers.

RESULT

The acoustic components and simulation circuit were well matched. One of the prototype can attenuate the noise more than 15 dB in the frequency range of 50-2000 Hz (19 dB at the highest).

CONCLUSION

The noise cancellation value of this earmuff has achieved international level and it can be mass-produced.

Errors and Omissions in Anesthesia: A Pilot Study Using a Pilot???s Checklist

There are recent concerns that anesthesiologists are becoming less skilled in providing general anesthesia for Cesarean delivery. We considered whether a verbal checklist would help in the preparation for this event. We created a list of items to be checked when preparing to administer general anesthesia for a Cesarean delivery using expert opinion. This list was loaded onto an electronic checklist system with voice prompts and tested on 20 anesthesiologists using a high-fidelity anesthesia simulator. Participants omitted to check a median of 13 (range, 7-23) of 40 items. Common omissions included not checking that the difficult intubation trolley was available and not optimizing the patient's head position. Most (95%) participants felt that the checklist was useful and 80% would like to use it for practicing simulated scenarios; 60% preferred a written checklist and 40% preferred the verbal checklist. Important checks may be forgotten when preparing to give a general anesthetic for Cesarean delivery, and the use of a checklist could improve patient safety.

Effects of automation of information-processing functions on teamwork

We investigated the effects of automation as applied to different stages of information processing on team performance in a complex decision-making task. Forty teams of 2 individuals performed a simulated Theater Defense Task. Four automation conditions were simulated with computer assistance applied to realistic combinations of information acquisition, information analysis, and decision selection functions across two levels of task difficulty. Multiple measures of team effectiveness and team coordination were used. Results indicated different forms of automation have different effects on teamwork. Compared with a baseline condition, an increase in automation of information acquisition led to an increase in the ratio of information transferred to information requested; an increase in automation of information analysis resulted in higher team coordination ratings; and automation of decision selection led to better team effectiveness under low levels of task difficulty but at the cost of higher workload. The results support the use of early and intermediate forms of automation related to acquisition and analysis of information in the design of team tasks. Decision-making automation may provide benefits in more limited contexts. Applications of this research include the design and evaluation of automation in team environments.

Adaptive automation of human-machine system information-processing functions

The goal of this research was to describe the ability of human operators to interact with adaptive automation (AA) applied to various stages of complex systems information processing, defined in a model of human-automation interaction. Forty participants operated a simulation of an air traffic control task. Automated assistance was adaptively applied to information acquisition, information analysis, decision making, and action implementation aspects of the task based on operator workload states, which were measured using a secondary task. The differential effects of the forms of automation were determined and compared with a manual control condition. Results of two 20-min trials of AA or manual control revealed a significant effect of the type of automation on performance, particularly during manual control periods as part of the adaptive conditions. Humans appear to better adapt to AA applied to sensory and psychomotor information-processing functions (action implementation) than to AA applied to cognitive functions (information analysis and decision making), and AA is superior to completely manual control. Potential applications of this research include the design of automation to support air traffic controller information processing.

Automation in future air traffic management: effects of decision aid reliability on controller performance and mental workload

Future air traffic management concepts envisage shared decision-making responsibilities between controllers and pilots, necessitating that controllers be supported by automated decision aids. Even as automation tools are being introduced, however, their impact on the air traffic controller is not well understood. The present experiments examined the effects of an aircraft-to-aircraft conflict decision aid on performance and mental workload of experienced, full-performance level controllers in a simulated Free Flight environment. Performance was examined with both reliable (Experiment 1) and inaccurate automation (Experiment 2). The aid improved controller performance and reduced mental workload when it functioned reliably. However, detection of a particular conflict was better under manual conditions than under automated conditions when the automation was imperfect. Potential or actual applications of the results include the design of automation and procedures for future air traffic control systems.

How can ergonomics influence design? Moving from research findings to future systems

Ergonomics design is about the creation of future work. So how can ergonomics research support and inform design if its findings are cast in a language oriented towards current work derived from field observations or laboratory settings? In this paper we assess instances of three different strands (experimental, ethnomethodological, and surveys) of ergonomics research on paper flight strips in air traffic control, for how they analytically confront future work and how they make the findings relevant or credible with respect to future work. How these justifications come about, or how valid (or well argued for) they are, is rarely considered in the ergonomics literature. All three strands appear to rely on rhetoric and argument as well as method and analysis, to justify findings in terms of their future applicability. Closing the gap between research results and future work is an important aim of the ergonomic enterprise. Better understanding of the processes necessary to bridge this gap may be critical for progress in ergonomics research and for the use of its findings in actual design processes.

[Radiation safety of exploitation of radiation sources at the civil aviation airlines]

Radiation risks from isotope-containing equipment, and ionizing and unused X-ray radiation sources are characterized and relevant normative documents with safety requirements to radiation sources installation, radiation safety of aircraft servicing and repair, hand luggage control and heavy luggage registration, personal protection items, system of radiation monitoring at airlines and aircraft works, and liability for breach of performance guidelines are cited.

Mental workload in air traffic control: an index constructed from field tests

BACKGROUND

Mental workload assessment is a recurrent issue in air traffic control (ATC). Studies of ATC have used either objective aspects, i.e., numbers and distribution of aircraft, or subjective factors, such as self-imposed performance and stress levels, with mixed results. This is partly due to the difficulty in bringing together comparable data pertaining to both air traffic, with its ever-changing distribution, and judgement or quickly fluctuating psychophysiological variables.

METHODS

We propose a method of mental load estimation devised to take into account both objective traffic variables and the additional load imposed by subjective effects, including the seriousness of conflicts and the time-pressure for their resolution. First, we developed a traffic load index (TLI) to identify time boundaries during which additional load may occur. Then we quantified the additional load according to the air traffic situation.

RESULTS

TLI was developed from analysis of 25 h of recordings of radar control sessions involving 25 professional air traffic controllers at a major airport. Results were then compared with a simple objective index (number of aircraft) and subjective workload ratings (NASA-TLX test). The whole population (intersubjects analysis) showed a better correlation between the TLI and the self-rated workload than for the number of aircraft alone. Among the controllers who rated more than one level of workload through the TLX-test, 77.8% showed better correlation between TLI and TLX than between N and TLX (intrasubjects analysis).

CONCLUSION

Workload estimation should integrate both objective task variables and subjective evaluations associated with them.