Morris C Craig
Bureau of Transportation Statistics, US Department of Transportation, Washington, DC 20590, USA.
Aviat Space Environ Med. 2005 Apr;76(4):357-65.
Midair collisions cause loss of life and property and undermine general aviation; they also represent failures of the see-and-avoid concept in air traffic control. This study identifies limitations of the see-and-avoid concept.
Analysis of National Transportation Safety Board data on 159 U.S. civil aviation midair collisions and limitations of the see-and-avoid concept.
On average, there were 15.6 midair collisions annually from 1991 through 2000. At least one aircraft was maneuvering in 88% of collisions, and both in 70%. There were 77% that involved arrival to, departure from, or flight over an airport, with 61% in the traffic pattern. Head-tail collisions were more frequent in the traffic pattern than out (28.3%, 2.8%, p < 0.05). Other horizontal convergence angles were equally frequent in or out of the pattern: head-on (8.3%, 11.0%), obtuse (11.0%, 8.3%), and acute (13.8%, 16.6%).
Because the relative bearing to each aircraft on an unaccelerated collision course is constant, pilots sometimes cannot see converging aircraft when climbing, descending, or level. Even if a converging aircraft is unobstructed, it appears small, motionless, camouflaged, and inconspicuous until imminent impact. A statistical model reveals that the probabilities of seeing and avoiding a converging 40-ft aircraft, for an optimal observer or theoretical pilot scanning 2/3 or 1/3 of the time, respectively, are less than 0.91, 0.60, 0.30 at 200 kn; 0.49, 0.32, 0.16 at 300 kn; 0.28, 0.18, 0.09 at 400 kn; and 0.15, 0.10, 0.05 at 500 kn. The see-and-avoid concept has striking physical and behavioral limitations.
空中碰撞会导致人员伤亡和财产损失，破坏通用航空；它们还代表了空中交通管制中“看到并避让”概念的失效。本研究确定了“看到并避让”概念的局限性。
分析美国国家运输安全委员会关于159起美国民航空中碰撞的数据以及“看到并避让”概念的局限性。
1991年至2000年期间，平均每年发生15.6起空中碰撞。在88%的碰撞中至少有一架飞机在机动，70%的碰撞中两架飞机都在机动。77%的碰撞涉及到达、离开机场或飞越机场，61%发生在交通模式中。在交通模式中，追尾碰撞比模式外更频繁（28.3%，2.8%，p<0.05）。其他水平交汇角度在模式内或模式外出现的频率相同：迎头（8.3%，11.0%）、钝角（11.0%，8.3%）和锐角（13.8%，16.6%）。
由于在未加速的碰撞航向上，每架飞机的相对方位是恒定的，飞行员在爬升、下降或平飞时有时看不到正在交汇的飞机。即使交汇飞机没有遮挡，在即将碰撞之前，它看起来也很小、静止、有伪装且不显眼。一个统计模型显示，对于最佳观察者或理论飞行员分别以2/3或1/3的时间进行扫描，在200节时看到并避让一架40英尺交汇飞机的概率分别小于0.91、0.60、0.30；在300节时为0.49、0.32、0.16；在400节时为0.28、0.18、0.09；在500节时为0.15、0.10、0.05。“看到并避让”概念存在明显的物理和行为局限性。
