In-flight Events Research Articles

A Descriptive Study ofCasualties Evacuated Out ofAfghanistan by Critical Care Air Transport Teams During the Withdrawal ofU.S. Troops.

The War in Afghanistan ended in August 2021. Evacuation from the country was a large effort during the last days of the conflict. During evacuation efforts at Kabul Hamid Karzai International Airport, a suicide bombing occurred necessitating emergent medical care for many injured troops and civilians. The U.S. Air Force Critical Care Air Transport Teams (CCATTs) played a role in the medical care provided during the operations in Afghanistan. We report on in-flight events and interventions that took place during the final days of the Afghanistan withdrawal. We performed a retrospective chart review of patients requiring aeromedical evacuation from the Afghanistan theater of operations by CCATT from July 1 to August 30, 2021. From the CCATT patient care record, data abstractors collected patient characteristics, flight information, vital signs, laboratory values, in-flight interventions, and in-flight events in a study-specific electronic database. We performed descriptive analyses of patient characteristics and in-flight interventions. This study was approved by the San Antonio Institutional Review Board. Nine patients were included in this analysis. Seven out of nine patients were foreign nationals; the remaining two were U.S. Marines. Five patients suffered penetrating injuries from gunshot wounds and four suffered blast injuries. Six received intravenous narcotic analgesia. Four received intravenous sedatives, and four received antibiotics in flight. Two patients required chest tube management. One patient received blood. Three patients were in acute respiratory distress. Severe injuries were sustained during the withdrawal efforts at the end of the War in Afghanistan. Critical Care Air Transport Teams played a role in the care and evacuation of patients out of theater during this unique and unprecedented time. Even given the limitations associated with retrospective studies and a small sample size, information reported in this study can help inform future decisions, and aid in preparatory efforts for future operations, that may require medical care by CCATT.

Harmonization and Verification of Three National European Icing Forecast Models Using Pilot Reports

The Single European Sky Air Traffic Management Research (SESAR) program aims at modernizing and harmonizing the European airspace, which currently has a strongly fragmented character. Besides turbulence and convection, in-flight icing is part of SESAR and can be seen as one of the most important meteorological phenomena, which may lead to hazardous flight conditions for aircraft. In this study, several methods with varying complexities are analyzed for combining three individual in-flight icing forecasts based on numerical weather prediction models from Deutscher Wetterdienst, Météo-France, and Met Office. The optimal method will then be used to operate one single harmonized in-flight icing forecast over Europe. As verification data, pilot reports (PIREPs) are used, which provide information about hazardous weather and are currently the only direct regular measure of in-flight icing events available. In order to assess the individual icing forecasts and the resulting combinations, the probability of detection skill score is calculated based on multicategory contingency tables for the forecast icing intensities. The scores are merged into a single skill score to give an overview of the quality of the icing forecast and enable comparison of the different model combination approaches. The concluding results show that the most complex combination approach, which uses iteratively optimized weighting factors for each model, provides the best forecast quality according to the PIREPs. The combination of the three icing forecasts results in a harmonized icing forecast that exceeds the skill of each individual icing forecast, thus providing an improvement to in-flight icing forecasts over Europe.

Hemodynamic events during en route critical care for patients with traumatic brain injury.

Exposure to stressors of flight may increase risk of secondary insults among critically injured combat casualties wounded with traumatic brain injury (TBI). The primary objective of this study was to describe the prevalence of hemodynamic events by phase of transport among patients with TBI transported by Critical Care Air Transport Teams (CCATT). We performed a secondary analysis of a retrospective cohort of 477 adults with moderate to severe TBI, who required transport by CCATT to Germany from multiple hospitals in the Middle East between January 2007 and May 2014. We abstracted clinical data from handwritten CCATT medical records. Hemodynamic events included systolic blood pressure <100 mm Hg and cerebral perfusion pressure <60 mm Hg. We calculated the proportion of patients experiencing hemodynamic events for each phase of flight. We analyzed 404 subjects after exclusions for catastrophic brain injury (n = 39) and missing timestamps (n = 34). Subjects had high Injury Severity Scores (median, 29; interquartile range [IQR], 21-35) and a median flight time of 423 minutes (IQR, 392.5-442.5 minutes). The median of documented in-flight vital signs was 8 measurements (IQR, 6.5-8 measurements). Documented systolic blood pressure in-flight events occurred in 3% of subjects during ascent, 7.9% during early flight, 7.7% during late flight, and 2.2% during descent, with an overall in-flight prevalence of 13.9%. Among patients with intracranial pressure monitoring (n = 120), documented cerebral perfusion pressure events occurred in 5% of subjects during ascent, 23% during early flight, 17% during late flight, and 5.8% during descent, with an overall in-flight prevalence of 30.8%. Documented hemodynamic events occurred during each phase of flight in severely injured combat casualties wounded with TBI, and episodic documentation likely underestimated the actual in-flight frequency of secondary insults. Prognostic and epidemiological; Level IV.

Association of Hypocalcemia With Mortality of Combat Casualties With Brain Injury and Polytrauma Transported by Critical Care Air Transport Teams.

Hypocalcemia at hospital presentation is associated with increased mortality in trauma patients with hemorrhagic shock. The 2019 updates to the Joint Trauma System Damage Control Resuscitation (DCR) Clinical Practice Guideline recommend calcium supplementation for ionized calcium (iCa) measurements <1.2 mmol/L. Ionized calcium goals for en route critical care (ERCC) following DCR are less defined, and the impact of in-flight hypocalcemia events among critically injured combat wounded is unknown. This study aimed to describe the association between hypocalcemia and mortality for combat-wounded with brain injury and polytrauma requiring transport by Critical Care Air Transport Teams (CCATT). We performed a secondary analysis of a retrospective cohort of patients with moderate-to-severe traumatic brain injury transported by CCATT out of combat theater between January 2007 and May 2014. Additional inclusion criteria included polytrauma and at least one documented in-flight iCa measurement. We categorized exposures based on the minimum in-flight iCa measurement as severe hypocalcemia (iCa <0.9 mmol/L), hypocalcemia (iCa 0.9-1.11 mmol/L), and never hypocalcemic (iCa ≥1.12 mmol/L). The primary outcome measure was mortality. We calculated descriptive statistics and performed multivariate logistic regression to assess the association between hypocalcemia and mortality. We analyzed 190 subjects, with a median age of 24 years (interquartile range [IQR] 21 to 29 years) and 97.7% male gender. Explosive injuries (82.1%) and gunshot wounds (6.3%) were the most common mechanisms of injury. The median injury severity score was 34 (IQR 27 to 43). During the flight, 11.6% of patients had severe hypocalcemia, and 39.5% had hypocalcemia. Among patients with any hypocalcemia measurement in-flight (n = 97), 41.2% had hypocalcemia on pre-flight iCa, 28.9% received blood products in-flight, and 23.7% received in-flight calcium supplementation. Only 32.4% of patients with hypocalcemia or severe hypocalcemia in the setting of vasopressor administration received in-flight calcium supplementation. There was no significant difference in mortality between severe hypocalcemia (9.1%), hypocalcemia (5.3%), and never hypocalcemic (3.2%) patients even after controlling for pre-flight variables. In-flight hypocalcemia events were common among critically ill combat-wounded polytrauma patients transported by CCATT but were not associated with differences in mortality. Future training should emphasize the need for calcium correction among ERCC patients requiring vasopressors. Future studies with larger sample sizes of patients receiving ERCC are needed to assess the association between in-flight calcium supplementation with clinical outcomes.

Evacuation Strategies for U.S. Casualties with Traumatic Brain Injury (TBI) with and without Polytrauma.

According to the Military Health System Traumatic Brain Injury (TBI) Center of Excellence, 51,261 service members suffered moderate to severe TBI in the last 21 years. Moderate to severe TBI in service members is usually related to blast injury in combat operations, which necessitates medical evacuation to higher levels of care. Prevention of secondary insult, and mitigation of the unique challenges associated with the transport of TBI patients in a combat setting are important in reducing the morbidity and mortality associated with this injury. The primary goal of this study was a secondary analysis comparing the impact of time to transport on clinical outcomes for TBI patients without polytrauma versus TBI patients with polytrauma transported out of the combat theater via Critical Care Air Transport Teams (CCATT). Our secondary objective was to describe the occurrence of in-flight events and interventions for TBI patients without polytrauma versus TBI with polytrauma to assist with mission planning for future transports. We performed a secondary analysis of a retrospective cohort of 438 patients with TBI who were evacuated out of theater by CCATT from January 2007 to May 2014. Polytrauma was defined as abbreviated injury scale (AIS) of at least three to another region in addition to head/neck. Time to transport was defined as the time (in days) from injury to CCATT evacuation out of combat theater. We calculated descriptive statistics and examined the associations between time to transport and preflight characteristics, in-flight interventions and events, and clinical outcomes for TBI patients with and without polytrauma. We categorized patients into two groups, those who had a TBI without polytrauma (n = 179) and those with polytrauma (n = 259). Within each group, we further divided those that were transported within 1 day of injury, in 2 days, and 3 or more days. Patients with TBI without polytrauma transported in 1 or 2 days were more likely to have a penetrating injury, an open head injury, a preflight Glascow Coma Score (GCS) of 8 or lower, and be mechanically ventilated compared to those transported later. Patients without polytrauma who were evacuated in 1 or 2 days required more in-flight interventions compared to patients without polytrauma evacuated later. Patients with polytrauma who were transported in 2 days were more likely to receive blood products, and patients with polytrauma who were evacuated within 1 day were more likely to have had at least one episode of hypotension en route. Polytrauma patients who were evacuated in 2-3 days had higher hospital days compared to polytrauma with earlier evacuations. There was no significant difference in mortality between any of the groups. In patients with moderate to severe TBI transported via CCATT, early evacuation was associated with a higher rate of in-flight hypotension in polytrauma patients. Furthermore, those who had TBI without polytrauma that were evacuated in 1-2 days received more in-flight supplementary oxygen, blood products, sedatives, and paralytics. Given the importance of minimizing secondary insults in patients with TBI, recognizing this in this subset of the population may help systematize ways to minimize such events. Traumatic Brain Injury patients with polytrauma may benefit from further treatment and stabilization in theater prior to CCATT evacuation.

Analysis of Altitude Hypoxia Training and In-Flight Hypoxia Events among the Helicopter Aircrews.

All aircrews are required to undertake the altitude hypoxia training and be familiarized with the hypobaric effect on their physiological regulation. Due to the characteristics of the helicopter aircrafts, few researches have reported in-flight hypoxia events among the helicopter aircrews. The main goal of this study was designed to compare the hypoxia symptoms of helicopter aircrews between the altitude hypoxia training and during flight. We developed a questionnaire to collect the details of chamber flights and in-flight hypoxia events in 2019. All data were managed by the SPSS software and two-tailed 0.05 alpha level was considered as a significant level. Of the 213 study participants, there were eight (3.8%) cases that experienced hypoxia symptoms during the flight. The top five symptoms that appeared both in the last and current altitude hypoxia trainings were visual impairment (20.7%), difficulty concentrating (12.7%), tiredness (12.2%), cognitive impairment (8.0%), and air hunger (5.2%). Meanwhile, the frequency of those symptoms above was not significantly different from the last or current training compared with those in-flight hypoxia events. The survey unveiled a series of consistency correlations of hypoxia symptoms between the chamber flights and in-flight environment for the helicopter aircrew group.

Contributions of Hypoxia-Awareness Training to the Familiarization of Personal Symptoms for Occupational Safety in the Flight Environment.

Hypoxia remains a flight-safety issue in terms of aviation medicine. Hypoxia-awareness training has been used to help aircrew members recognize personal hypoxia symptoms. There is still no study, as yet, to establish the association of within-subject data between inflight hypoxia events and the altitude chamber. The main purpose of our study was to use paired subjects’ data on inflight hypoxia symptoms compared with those experienced during training. A questionnaire was developed to obtain information on military aircrew members in 2018. Among 341 subjects, 46 (13.49%) suffered from inflight hypoxia. The majority of the subjects detected ongoing inflight hypoxia on the basis of their previous experience with personal hypoxia symptoms or sensations in previous chamber flights. Of the top five hypoxia symptoms, the data revealed that hot flashes, poor concentration, and impaired cognitive function appeared both during the inflight events and during the hypoxia-awareness training. The occurrence rate of hypoxia symptoms was found to not be significantly different between the in-flight events and the past chamber flights through an analysis of within-subject data. Because the individual memory had faded away over time, fresher hypoxia awareness training is still mandatory and valuable to recall personal hypoxia experience for military aircrew members.

Natural Language Processing Based Method for Clustering and Analysis of Aviation Safety Narratives

The complexity of commercial aviation operations has grown substantially in recent years, together with a diversification of techniques for collecting and analyzing flight data. As a result, data-driven frameworks for enhancing flight safety have grown in popularity. Data-driven techniques offer efficient and repeatable exploration of patterns and anomalies in large datasets. Text-based flight safety data presents a unique challenge in its subjectivity, and relies on natural language processing tools to extract underlying trends from narratives. In this paper, a methodology is presented for the analysis of aviation safety narratives based on text-based accounts of in-flight events and categorical metadata parameters which accompany them. An extensive pre-processing routine is presented, including a comparison between numeric models of textual representation for the purposes of document classification. A framework for categorizing and visualizing narratives is presented through a combination of k-means clustering and 2-D mapping with t-Distributed Stochastic Neighbor Embedding (t-SNE). A cluster post-processing routine is developed for identifying driving factors in each cluster and building a hierarchical structure of cluster and sub-cluster labels. The Aviation Safety Reporting System (ASRS), which includes over a million de-identified voluntarily submitted reports describing aviation safety incidents for commercial flights, is analyzed as a case study for the methodology. The method results in the identification of 10 major clusters and a total of 31 sub-clusters. The identified groupings are post-processed through metadata-based statistical analysis of the learned clusters. The developed method shows promise in uncovering trends from clusters that are not evident in existing anomaly labels in the data and offers a new tool for obtaining insights from text-based safety data that complement existing approaches.

Patients With Traumatic Brain Injury Transported by Critical Care Air Transport Teams: The Influence of Altitude and Oxygenation during Transport.

Traumatic brain injuries (TBIs) are life-threatening, and air transport of patients with TBI requires additional considerations. To mitigate the risks of complications associated with altitude, some patients fly with a cabin altitude restriction (CAR) to limit the altitude at which an aircraft's cabin is maintained. The goal of this study was to examine the effects of CARs on patients with TBI transported out of theater via Critical Care Air Transport Teams. We conducted a retrospective chart review of patients with moderate-to-severe TBI evacuated out of combat theater to Landstuhl Regional Medical Center via Critical Care Air Transport Teams. We collected demographics, flight and injury information, procedures, oxygenation, and outcomes (discharge disposition and hospital/ICU/ventilator days). We categorized patients as having a CAR if they had a documented CAR or maximum cabin altitude of 5,000feet or lower in their Critical Care Air Transport Teams record. We calculated descriptive statistics and constructed regression models to evaluate the association between CAR and clinical outcomes. We reviewed the charts of 435 patients, 31% of which had a documented CAR. Nineteen percent of the sample had a PaO2 lower than 80mm Hg, and 3% of patients experienced a SpO2 lower than 93% while in flight. When comparing preflight and in-flight events, we found that the percentage of patients who had a SpO2 of 93% or lower increased for the No CAR group, whereas the CAR group did not experience a significant change. However, flying without a CAR was not associated with discharge disposition, mortality, or hospital/ICU/ventilator days. Further, having a CAR was not associated with these outcomes after adjusting for additional flights, injury severity, injury type, or preflight head surgery. Patients with TBI who flew with a CAR did not differ in clinical outcomes from those without a CAR.

NRC particle detection probe: test cell to flight

Purpose High-altitude ice crystals (HAICs) are causing one in-flight event or more per month for commercial aircraft. The effects include preventing air data probes (pitot pressure and total air temperature in particular) from functioning correctly and causing engines to roll back and shut down. The purpose of this study is to describe the process used by the National Research Council Canada (NRC) to develop and test a particle detection probe (PDP). The probe mounts on the fuselage of aircraft to sense and quantify the ice crystals in the environment. Design/methodology/approach The probe was demonstrated on the NRC Convair and Airbus A340 research aircraft as part of the European Union HAIC programme. The probe was ruggedised, adapted for easy installation in standard aircraft fittings and tested in a variety of conditions for longevity and endurance. Findings Efforts to achieve the safety requirements for flight on aircraft are discussed. The challenges, surprises and opportunities for testing on which the development group is capitalised are also presented. Practical implications It was demonstrated that the detectors gave signals proportional to the ice crystal content of clouds, and results demonstrating the functionality of the probe are presented. Originality/value This paper describes the multi-year process of developing the NRC PDP from a test cell sensor for detecting engine exhaust contaminants on an aircraft ice crystal detection probe. The work included over 20 flight tests on NRC aircraft and the Airbus HAIC test programme.

Responding to an Unexpected In-Flight Event: Physiological Arousal, Information Processing, and Performance.

The study was designed to investigate whether a simulated unexpected abnormal flight event can lead to startle and explore differences in behavioral responses between expected and unexpected abnormal flight events. Recent research suggests startle (an autonomic response to an acute stimulus) following unexpected abnormal flight events can impact pilot performance and can increase the probability of a negative outcome following the event. Information processing, physiological measures, and performance differences between responses to expected and unexpected flight events were compared. General aviation (GA) pilots flew a series of flights in a fixed-base flight simulator including two experimental flights which included an unexpected and an expected, engine failure. During the flights, heart rate, eye tracking, and flight data were recorded. During the unexpected engine failure, pilots showed greater increases in heart rate and pupil dilation. Significant differences in scanning were evident with fewer areas scanned following the unexpected event. During the unexpected engine failure, performance was impaired when compared to the expected events. However, poor performance was not associated with higher levels of arousal. The study provides an empirical demonstration of impaired pilot response to unexpected events with associated symptoms consistent with the induction of startle. The present research builds on Landman et al.'s conceptual model of startle and surprise. Standardized training protocols may not adequately prepare pilots to deal with the unexpected effects of startle in real-world encounters. Introducing greater variety into training events may be useful. The effects of startle in disrupting well-trained responses may also occur in areas other than aviation where critical events may occur unexpectedly or present in an unfamiliar manner.

Understanding pilot response to flight safety events using categorisation theory

Categorisation theory explains our ability to recognise events in terms of a similarity overlap between either a prototypical, ideal case or a stored exemplar derived from experience. Evidence from aviation accident reports indicate that pilots are not always able to recognise flight safety events in real-time and this can lead to undesirable pilot behaviour. Flight safety events may not always arise in recognisable formats, especially as rare and unusual cue combinations are possible. Correspondence with prototypes or exemplars may be weak, creating borderline cases and harming recognition. In this article we extend categorisation theory to develop a new framework which characterises flight safety events. We model three case studies using the new framework to demonstrate how categorisation theory can be used to understand flight safety events of different types. Finally, we propose a roadmap for future research and discuss how categorisation theory could be applied to training or the organisation of flight crew reference material to improve response to inflight events.

Frequency and clinical spectrum of in-flight medical incidents during domestic and international flights.

Most medical practitioners are not specifically trained to diagnose or manage in-flight medical incidents, yet there may occur a moral obligation to do so when least expected. We felt that knowledge of the frequency of emergency versus non-serious medical incidents, in addition to the clinical spectrum of incidents most often encountered, would be of interest to medical practitioners and, in particular, critical care physicians, who happen to find themselves asked to assist with such events. To this end we collaborated with the Department of Medical Services of a major Australian airline to define the incidence, severity, and type of all in-flight medical events encountered over the course of a year's flights. We audited in-flight medical data collected over a continuous 12-month period, which covered 131,890 international and domestic flight sectors transporting more than 27 million passengers. There was an average of 296 medical events per month (3555 in total) making the per-flight incidence of a medical event approximately 1:40 (2.7%). Of these in-flight incidents, 915 (26%) were graded as emergencies, with the commonest descriptors of such incidents being either loss of consciousness (37%) or a suspected cardiovascular event (12%). Six of these 915 emergencies proved fatal. Twenty-one flights were diverted due to medical incidents (<0.016% of all flights), with 52% of these attributed to suspected cardiac events. In this series, medical in-flight events were recorded in approximately one in 40 flights, whereas medical emergencies occurred in approximately one in 150 flights.

항공사 기내이벤트가 브랜드가치와 브랜드충성도에 미치는 영향

항공사 기내이벤트가 브랜드가치와 브랜드충성도에 미치는 영향

Cardiac Inflight Incapacitations of U.S. Airline Pilots: 1995-2015.

Inflight medical incapacitations are rare events that can result in the loss of lives and aircraft. The potential for an in-flight medical event deserves the attention of certification authorities. Cardiac emergencies are among the most common serious events. The primary focus of this study was to examine whether the proportions of pilots with reported cardiac conditions could be used to identify those who had inflight medical incapacitations. The Civil Aerospace Medical Institute Inflight Incapacitation Registry was searched to identify airline pilots with a cardiac history and an inflight medical event between 1995 and 2015. The Federal Aviation Administration's Decision Support System was searched for airline pilots without an inflight medical event. The cardiovascular history of incapacitated pilots was then compared to that of airline pilots without incapacitation events. Although a significantly greater proportion of airline pilots with cardiac events had pacemakers than a control group with the same cardiac history who did not have inflight events, no significant difference was found in the proportions of other markers of cardiac health. The proportions of airline pilots with identified cardiac conditions could not be reliably used to identify which pilots had inflight incapacitations.DeJohn CA, Mills WD, Hathaway W, Larcher J. Cardiac inflight incapacitations of U.S. airline pilots: 1995-2015. Aerosp Med Hum Perform 2018; 89(9):837-841.

A model of low-velocity impact damage assessment of laminated composite structures

Laminated composites have important applications in modern aeronautical structures due to their extraordinary mechanical and environmental behaviour. Nevertheless, aircraft composite structures are highly vulnerable to impact damage, either by low-velocity sources during maintenance or high-velocity sources during in-flight events. Even barely visible impact damage induced by low-velocity loading, substantially reduces the residual mechanical performance and the safe-service life of the composites structures. Despite the extensive research already carried out, impact damage of laminated composite structures is still not well understood and it is an area of on-going research. Numerical modelling is considered as the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intra-laminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS® programme. The employed modelling approach is validated using numerical results found in the literature and the presented results show an acceptable correlation to the available literature data. It is demonstrated that the presented model is able to capture force-time response as well as damage evolution map for a range of impact energies.

KANO모형과 Timko의 고객만족계수를 이용한 항공사 기내이벤트 선호도 이해

The purpose of this study is to investigate customer perceptions toward in-flight events while considering the service differentiation strategy of airlines, via KANO's model. Timko's customer satisfaction coefficients for customer satisfaction and dissatisfaction with in-flight events suggest additional implications for the development of consumer-led in-flight events on airlines. The questionnaire used in this study included all 18 in-flight events actually implemented by several airlines throughout Korea. Respondents were asked to answer to a pair of positive and negative questions as to each event provided in their flight. The results of this study show that the 18 events can be divided into ten attractive quality factors, seven indifferent quality factors, and one natural quality factor. However, the unitary quality factor and the inverse quality factor are not shown in this study. Timko's customer satisfaction coefficients suggest an order of priority for these in-flight events. This study is significant particularly in that the concept of the KANO model was applied to analyze the customer preferences for in-flight events in operation. The results of this study will help airline service marketers make a rational decision based actual evidence rather than intuition when developing and implementing in-flight events that will further enhance service quality.

Dealing With Unexpected Events on the Flight Deck: A Conceptual Model of Startle and Surprise

Objective:A conceptual model is proposed in order to explain pilot performance in surprising and startling situations.Background:Today’s debate around loss of control following in-flight events and the implementation of upset prevention and recovery training has highlighted the importance of pilots’ ability to deal with unexpected events. Unexpected events, such as technical malfunctions or automation surprises, potentially induce a “startle factor” that may significantly impair performance.Method:Literature on surprise, startle, resilience, and decision making is reviewed, and findings are combined into a conceptual model. A number of recent flight incident and accident cases are then used to illustrate elements of the model.Results:Pilot perception and actions are conceptualized as being guided by “frames,” or mental knowledge structures that were previously learned. Performance issues in unexpected situations can often be traced back to insufficient adaptation of one’s frame to the situation. It is argued that such sensemaking or reframing processes are especially vulnerable to issues caused by startle or acute stress.Conclusion:Interventions should focus on (a) increasing the supply and quality of pilot frames (e.g., though practicing a variety of situations), (b) increasing pilot reframing skills (e.g., through the use of unpredictability in training scenarios), and (c) improving pilot metacognitive skills, so that inappropriate automatic responses to startle and surprise can be avoided.Application:The model can be used to explain pilot behavior in accident cases, to design experiments and training simulations, to teach pilots metacognitive skills, and to identify intervention methods.

En route intraosseous access performed in the combat setting

To describe and compare vascular access practices used by en route care providers during medical evacuation (MEDEVAC). This was a retrospective cohort study. Medical records of US military personnel injured in combat and transported by MEDEVAC teams were queried. The subjects were transported by military en route care providers, in the combat theater during Operation Enduring Freedom (OEF) between January 2011 and March 2014. The authors reviewed 1,267 MEDEVAC records of US casualties and included 832 subjects that had vascular access attempts. The outcome measures for this study were vascular access success rates, including intravenous (IV) and intraosseous (IO) attempts. Subjects were grouped by type of vascular access: None, peripheral intravenous (PIV), IO, and PIV + IO (combination of PIV and IO) and by vascular access (PIV or IO) success (No versus Yes). Survival rate, in-flight events, ventilator, intensive care and in hospital days, and 30-day outcomes were compared among groups. The authors used chisquare or Fisher's exact tests to evaluate categorical variables. Analysis of variance (ANOVA) or Kruskal-Wallis tests were used for continuous variables. Vascular access was attempted in 832 (66 percent) of the 1,267 subjects transported by MEDEVAC during this study period. The majority (n = 758) of the access attempts were PIV of which 93 percent (706/758) were successful. In 74 subjects, IO was the only access attempted with an 85 percent (n = 63) success rate. The overall success rate with IO placement was 88 percent. Intraosseous access has been used successfully in the combat setting and accounts for approximately 12 percent of vascular access in the MEDEVAC population the authors studied.

Validation of a nonlinear observer implementation for empennage loads estimation

The monitoring of aircraft structural loads shows promising potential for improvement in terms of aircraft maintenance. Monitored loads can be used for component specific overload detection and for targeted inspections on ground. This results in a reduction of the necessary on-ground time after in-flight events and consequently in a reduction of maintenance costs. Focusing model-based approaches for loads monitoring, a nonlinear Luenberger observer is adapted for the flight test aircraft UW-9 Sprint. The implementation of the observer structure containing a state and a disturbance observer, as well as the determination of the included feedback gains is explained. Within this article, the Loads Observer method is validated against flight test data, exemplarily for empennage loads. For this purpose, the empennage of the test aircraft is equipped with strain gages. The test equipment and its calibration are described. Regarding the assessment of combined maneuver and gust loads, the flight test execution including the performance of maneuvers in gusty conditions is demonstrated. Finally, the component loads estimation is compared to the loads measurement.