Robert R.A. van Doorn

Manual asymmetries in the temporal and spatial control of aimed movements

Right-handed participants performed aimed, left- and right-hand movements toward a fixed target in speed and precision conditions. The purpose was to determine detailed hand differences in the temporal and spatial control during the course of a movement. The results showed that hand differences pertaining to spatial control of movement direction occurred throughout movement execution, and that these differences were stronger in the high speed and low precision conditions. Furthermore, the left hand took more time to execute a movement than the right hand, especially in conditions of low speed and high precision. Detailed time analysis revealed that slowing down of the left hand specifically happened prior to peak acceleration and beyond peak deceleration. These detailed temporal hand differences reoccurred as additional discontinuities in the acceleration profile. These results suggest that the left hand has more difficulty at movement start than the right hand, possibly in overcoming initial inertia. It is discussed whether time-based manual asymmetries located near the end of movement execution should be explained in terms of increased feedback use, or should be related to hand differences regarding the possible active dissipation of mechanical energy at movement completion.

Accidents associated with aerobatic maneuvers in U.S. aviation.

BACKGROUND: Aerobatic flights are the most significant risk factor for fatal injury and make up 50% of U.S. accidents in general aviation involving airport transport pilots. METHOD: An analysis of the dangers of these maneuvers is presented using 25 yr of U.S. reported accidents. RESULTS: More than 80% of the 494 accidents were fatal. The main cause of accident was not maintaining (proper) altitude while adverse weather was not present as a cause of accident. Nearly half the number of pilots had over 7500 h of flight experience. Homebuilt aircraft appear significantly more likely to be part of a fatal accident, showing more structural, engine, and system failures. CONCLUSION: Although there is a downward trend in the number of aerobatic-related accidents, the reduction of accidents is much assisted by either regulation or awareness training of pilots using homebuilt aircraft in aerobatic maneuvers. Language: en

Sports aviation accidents: fatality and aircraft specificity.

Background: Sports aviation is a special category of general aviation characterized by diverse aircraft types and a predominantly recreational flight operation. A general comparison of aircraft accidents within sports aviation is missing, but should guide future research. Methods: A comparison of accidents in sports aviation was made using 2118 records from the National Transportation Safety Board for the period 1982-2007. In addition, the available denominator data from the Federal Aviation Administration were used to interpret the data. Results: The highest number of accidents was found with gliders (N = 991), but the highest relative number of fatal accidents came from ultra-light (45%) and gyroplane operations (40%), which are homebuilt more often than other aircraft types. The most common cause of accident in sports aviation was in-flight planning and decision-making (N = 200, 9.4%). The most frequent occurrences were hard landings and undershoots, of which the numbers differ significantly from one aircraft type to the other. Conclusions: Homebuilt aircraft are at particular risk in sports aviation. Although denominator data remain problematic for motorized sports aviation, these aircraft show a high proportion of homebuilt aircraft and, more importantly, a higher relative number of fatal accidents.

The Paradox of Helicopter Emergency Training

The practice of helicopter emergency procedures is not necessarily based on the prevalence of the emergencies in helicopter operations. Stuck pedal, hover autorotation, and ditching accidents taken from the National Transportation and Safety Board database illustrate this phenomenon. It is argued that manufacturers, aviation authorities, and flight schools determine the helicopter training curriculum and base their decisions on the safety of practice and the possibility of transfer of skill. Research on learning and transfer of skill in helicopter training is necessary to judge and possibly improve current helicopter training practices.