This study reports an investigation of the ability of subjects to estimate the velocity of the vehicle in which they travel. The experiment restricted sensory stimulation to the visual modality. The factor of interest is locus of retinal stimulation. Velocity and acceleration were the other variables. Time of observation was held constant to one second. Results show that the locus of retinal stimulation is significant in determining the accuracy of the estimates. Peripheral visual stimulation results in more accurate estimates of velocity than frontal visual stimulation. The acceleration of the vehicle alters the results.

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General aviation (GA) fatal accident records of airport transport pilots (ATPs) were compared to those of private pilots (PVTs). ATPs are safer GA pilots than the PVTs.They have comparable exposure in GA airplanes and account for 7.5% of all certified to fly, but only 3 4 5 % of the fatal accidents. ATPs are less often involved in pilot-induced accidents. Nearly 50% of ATP pilot-induced accidents occur during aerobatics. Often these risky aerial operations are performed below a safe altitude and are associated with the descriptors 'careless' and 'reckless'. The ATP aerobaticsrelated fatality is likely to occur in a multi-wing aeroplane with which he has little experience. The ATP aerobatics-related accident is likely to be of the spin, stall, or controlled flight into terrain variety, and to occur in summer or early autumn. 'The study used data from 13 680 general aviation (GA) accidents occurring between 1973 and 1983, inclusive. This represents approximately 30% of the 45 627 accidents that occurred during that period in GA aircraft.The accidents selected for study met the following criteria:(1) The GA flight was flown for personal (non-commercial) reasons.(2) The aircraft involved was a powered fixed-wing aeroplane.(3) The accident was a single-aircraft accident.(4) The aeroplane had not more than two pilots on board.

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This paper compares the effect of varying the sensory input (visual, auditory, kinesthetic, tactile and vestibular cues) on the appreciation of traveled velocity. A movie technique was developed to remove the effects of acceleration and present controlled frontal and peripheral visual cues. The range of velocities was extended to 100 mph. It is concluded that (1) the removal of the force sense feedback mechanism acts to reduce the ratio of the estimated to the presented or actual range of velocities. (2) There is direct variation of the absolute error with velocity as the range is extended to include high speeds. (3) Sensing of velocity based on peripheral visual stimulation appears to be more resistant to experimental artifacts, such as a monotonous environment, fatigue and the beta effect—apparent movement produced by an increase of illumination of part of the field—than frontal visual stimulation.