Biomedical subjects

S A Shappell

Publications and source records attributed to S A Shappell.

10 recordsLinked to original sources

PubMed2001

Human error analysis of commercial aviation accidents: application of the Human Factors Analysis and Classification system (HFACS).

BACKGROUND: The Human Factors Analysis and Classification System (HFACS) is a general human error framework originally developed and tested within the U.S. military as a tool for investigating and analyzing the human causes of aviation accidents. Based on Reason's (1990) model of latent and active failures, HFACS addresses human error at all levels of the system, including the condition of aircrew and organizational factors. The purpose of the present study was to assess the utility of the HFACS framework as an error analysis and classification tool outside the military. METHODS: The HFACS framework was used to analyze human error data associated with aircrew-related commercial aviation accidents that occurred between January 1990 and December 1996 using database records maintained by the NTSB and the FAA. RESULTS: Investigators were able to reliably accommodate all the human causal factors associated with the commercial aviation accidents examined in this study using the HFACS system. In addition, the classification of data using HFACS highlighted several critical safety issues in need of intervention research. CONCLUSION: These results demonstrate that the HFACS framework can be a viable tool for use within the civil aviation arena. However, additional research is needed to examine its applicability to areas outside the flight deck, such as aircraft maintenance and air traffic control domains.

Accidents, Aviation↗

PubMed1999

Human error and crew resource management failures in Naval aviation mishaps: a review of U.S. Naval Safety Center data, 1990-96.

The present study examined the role of human error and crew-resource management (CRM) failures in U.S. Naval aviation mishaps. All tactical jet (TACAIR) and rotary wing Class A flight mishaps between fiscal years 1990-1996 were reviewed. Results indicated that over 75% of both TACAIR and rotary wing mishaps were attributable, at least in part, to some form of human error of which 70% were associated with aircrew human factors. Of these aircrew-related mishaps, approximately 56% involved at least one CRM failure. These percentages are very similar to those observed prior to the implementation of aircrew coordination training (ACT) in the fleet, suggesting that the initial benefits of the program have not persisted and that CRM failures continue to plague Naval aviation. Closer examination of these CRM-related mishaps suggest that the type of flight operations (preflight, routine, emergency) do play a role in the etiology of CRM failures. A larger percentage of CRM failures occurred during non-routine or extremis flight situations when TACAIR mishaps were considered. In contrast, a larger percentage of rotary wing CRM mishaps involved failures that occurred during routine flight operations. These findings illustrate the complex etiology of CRM failures within Naval aviation and support the need for ACT programs tailored to the unique problems faced by specific communities in the fleet.

Accidents, Aviation↗

PubMed1996

Chronopharmacokinetics and chronopharmacodynamics of dextromethamphetamine in man.

Stimulants, in particular the amphetamines, have been studied as countermeasures to fatigue induced by circadian desynchronosis and extended flight operations. To make recommendations concerning the use of dextromethamphetamine for operational tasks, its chronopharmacokinetic and chronopharmacodynamic profiles and influence on circadian rhythms as a countermeasure to performance deficits and fatigue were studied. Ten male volunteers, divided into two groups of five each, were given 30 mg/70 kg of oral dextromethamphetamine during two test sessions one week apart and were evaluated with cognitive (dichotic listening, pattern recognition, and compensatory tracking), subjective (fatigue scale), and physiologic (blood pressure) testing. Session order was counterbalanced with dextromethamphetamine administration at either 8:40 AM or 8:40 PM during session one and a crossover to the other time during session two. Subjective and cognitive testing was begun 1.5 hours before dextromethamphetamine administration and continued every half hour until 12.5 hours after administration. Blood pressure was measured immediately before behavioral testing. Serum and urine were collected at regular intervals for gas chromatography/mass spectrometer analysis of methamphetamine and one of its metabolites, amphetamine. No differences were found in the day-versus-night pharmacokinetic profile of dextromethamphetamine. Cognitive performance and subjective fatigue improved after daytime administration of dextromethamphetamine in comparison to performance before drug administration. This effect was suppressed during the circadian trough, which occurred approximately 8 hours into the night sessions (4:30 AM). No correlations were seen between serum concentration of methamphetamine and measured behavioral parameters.

Adult↗

PubMed1996

U.S. naval aviation mishaps, 1977-92: differences between single- and dual-piloted aircraft.

The present study examined U.S. Naval aircraft mishap trends between January 1977 and December 1992 using all Class A, B, and C mishaps. Results of this investigation revealed that mishaps attributable to both human error and mechanical/environmental factors have declined steadily over the past 16 years, although mishaps attributed to human error have declined at a much slower rate. For those mishaps attributed to human error, differences were observed between single- and dual-piloted aircraft when phase-of-flight (takeoff, in-flight, landing) and time-of-day were evaluated. For single-piloted aircraft, in-flight mishaps constituted the highest proportion of mishaps during the day ( > 55%), while landing mishaps constituted the highest proportion of mishaps during the evening and night (43-65%). For dual-piloted aircraft, no consistent variation was evident for phase-of-flight and time-of-day. In-flight (approx. 55%) mishaps constituted the highest proportion of mishaps across all times of day, followed by landing (approx. 35%), and takeoff (approx. 10%) mishaps. These data support focused rather than global investigations of aviation mishaps.

Accidents, Aviation↗

PubMed1995

Naval flight deck injuries: a review of Naval Safety Center data, 1977-91.

A comprehensive review of injuries sustained by personnel working on naval flight decks between January 1977 and December 1991 was conducted using database records maintained at the U.S. Naval Safety Center, Norfolk, VA. Data included all fatalities, permanent total disabilities, permanent partial disabilities, and major injuries resulting in 5 or more lost work days. Injuries were coded using ICD-9-CM codes for analysis. A total of 918 flight deck personnel were reported injured during this 15-yr period, including 43 fatalities, 5 permanent total disabilities, 42 permanent partial disabilities, and 828 major injuries. Of the non-fatalities, a plethora of fractures, traumatic amputations, major lacerations, dislocations, contusions, concussions, burns, crushing injuries, sprains, and strains were reported. Nearly all naval platforms with a flight deck reported an injury. While an average of 51 injuries per 100,000 aircraft recoveries were reported annually on aircraft carriers from 1977-86, a marked reduction to a rate of roughly 30 injuries was observed annually from 1987-90. What makes injuries sustained on the flight deck particularly disconcerting is that over 90% can be attributed to human causal factors.

Accidents, Aviation↗

PubMed1995

Tobacco use and smoking policy perceptions onboard an aircraft carrier.

Prior to implementing a shipwide no-smoking policy, the crew of U.S.S. Theodore Roosevelt (CVN 71) participated in a voluntary survey on tobacco-related matters. The survey queried participants on their tobacco-use history, subjective exposure to environmental tobacco smoke (ETS), and attitudes related to smoking policy prior to the cessation of all smoking activities aboard ship. Of the 2,221 crewmembers who participated (74% response rate), 36% classified themselves as current cigarette smokers. Nonsmokers estimated their general exposure to ETS between "low" to "moderate." Of all participants, 57% were in favor of the current restricted smoking policy, including 18% of currently smoking personnel. Follow-up research is being conducted to assess the long-term impact of the no-smoking policy on changes in attitudes regarding policy, tobacco-use rates, and ETS exposure.

Adult↗

PubMed1995

The effects of tyrosine on cognitive performance during extended wakefulness.

Tyrosine, a large neutral amino acid found in dietary proteins, has received recent attention as a potential treatment for stress. The behavioral effects of tyrosine were examined during an episode of continuous nighttime work involving one night's sleep loss. Subjects performed nine iterations of a battery of performance tasks and mood scales for approximately 13 h, beginning at 1930 and ending at 0820. They remained awake throughout the day on which the experiment began and were awake for more than 24 h by the end of testing. Six hours after the experiment began, one-half of the subjects received 150 mg.kg-1 tyrosine in a split dose while the other half received cornstarch placebo in a double-blind procedure. Tyrosine administration was associated with a significant amelioration of the usual performance decline on a psychomotor task and a significant reduction in lapse probability on a high-event-rate vigilance task. The improvements lasted on the order of 3 h. The results of this study also suggest that tyrosine is a relatively benign treatment at this dose. After further testing with other doses and timing of administration, tyrosine may prove useful in counteracting performance decrements during episodes of sustained work coupled with sleep loss.

Adult↗

PubMed1986

No decrement in visual P300 amplitude during extended performance of the oddball task.

Research indicates that in visual sustained attention paradigms, the amplitude of the P300 component of the event-related potential invoked by target (critical) stimuli shows a decrement in amplitude. This amplitude decrement parallels decrements in vigilance performance that result from the difficult discrimination that is typically required between the infrequent targets and the frequent nontargets (neutral stimuli). In contrast, target stimulus P300 does not appear to show a decrement across large numbers of trials during performance of the "oddball" paradigm, in which targets and nontargets are highly discriminable. The present study measured target and nontarget P300 amplitude during performance of a visual oddball paradigm extended over an interval of some 3 1/2 hours, a period well in excess of the 3/4 hour intervals employed in previous research. The results indicated no decrement in P300 amplitude as a function of time for either targets or nontargets. The only significant relationship between P300 and behavioral data was an inverse correlation across oddball runs between average nontarget P300 amplitude and total number of targets missed.

Adult↗

PubMed1985

Individual differences in visual event-related potentials: P300 cognitive augmenting/reducing parallels N100 sensory augmenting/reducing.

In a visual event-related potential experiment, both N100 augmenting/reducing data and oddball paradigm P300 data were collected from the same subjects. A significant correlation was obtained between augmenting/reducing and the degree to which stimulus probability affected P300 amplitude. Subjects who augment/reduce in response to increased stimulus brightness in the sensory domain also appear to augment/reduce in response to low probability in the cognitive domain.

Adult↗

PubMedDate not supplied

GC-MS determination of amphetamine and methamphetamine in human urine for 12 hours following oral administration of dextro-methamphetamine: lack of evidence supporting the established forensic guidelines for methamphetamine confirmation.

Ten human volunteers, naive to amphetamines and divided into two groups of five each, were given an oral dose of 30 mg/70 kg D-methamphetamine in one of two different paradigms: the initial dose at 0930 h or the initial dose at 2130 h. One week later, each subject was crossed over with regard to time but given the same dose. A total of 214 urine specimens were collected either prior to dosing or at each micturition for a 12-h period post dose. Specimens were analyzed on a blind basis for methamphetamine and one of its metabolites, amphetamine, by gas chromatography-mass spectrometry (GC-MS) using coinjection of extracted sample and pentafluoropropionic anhydride and selected-ion monitoring. Approximately 20% of the D-methamphetamine was recovered unchanged from the urine specimens, and 2% was recovered as amphetamine. The mean urine methamphetamine concentration in both groups reached a maximum within 4-6 h and declined thereafter. A residual amount of methamphetamine was found in some predose specimens at the crossover evaluation, reflecting that methamphetamine may be detected in urine for up to 7 days. The amphetamine concentration reached a plateau by 4-6 h. This observation coupled with the finding that all subjects excreted approximately 2% of the methamphetamine dose as amphetamine suggested a saturable process for its biotransformation. Concentrations of both methamphetamine and amphetamine tended to be higher, but were not significantly different, for night administration. Methamphetamine concentrations were consistently greater than the 500-ng/mL cutoff in most post-dosing specimens, whereas amphetamine concentrations generally did not achieve the 200-ng/mL cutoff specified by the Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines for GC-MS confirmation of methamphetamine. Some specimens containing methamphetamine had no amphetamine metabolite. The current guidelines would have resulted in 90.2% of the specimens containing methamphetamine being ruled negative by confirmation following either night or day administration, whereas one subject following the initial day administration and another following night crossover administration would have been judged positive at most time intervals. These findings suggest that the current SAMHSA guidelines select for individual metabolic variations and that GC-MS confirmation of methamphetamine will result in most occasional users being ruled negative following an oral dose of methamphetamine while some will be ruled positive.

Administration, Oral↗