Viewing page 19 of 49

commenting on records which show that under actual 200-1/2 conditions one of every three approaches is missed, Roe(5) said: 

"This record is no reflection on the professional ability of the airline pilot for he is doing the best possible job with the tools at hand. It does, however, demonstrate graphically the inadequacy of his tools."
We feel that this demonstrates also that minimums of 200-1/2 are, at this time, not realistic when the human equation is taken into account with the instrumentation and speeds presently provided. In order to correct this, even at the expense of increased cockpit complexity, the addition of an instrument such as the Zero Reader or perhaps automatic approach may be the answer. In this case, even though another gadget is added, the actual task would be simplified and the safety level raised. 

Even as cockpits have become more complicated, so have the airway facilities. The number of ranges, ADF beacons, marker beacons, ILS, etc, have nearly saturated many areas. As more accurate fixes and approach systems have been evolved, the increased accuracy systems have been evolved, the increased accuracy has been used to cut approach times and increase the number of aircraft movements, while holding the same level of safety. This, instead of easing the pilot's job, has, in most cases, complicated it further.


In a recent fatal accident there is a possibility that the multiplicity of facilities and choice of approach methods may have confused the pilot to the point that the ADF was tuned to the wrong station for the chosen approach method with the result a mass of tangled wreckage on a hillside. 

The hitting mountain problem has been with us for many years and the often noted tendency for the fatal lack of terrain clearance to be very small gives rise to speculation as to the number of cases where the safe margin was equally slight. In other words, no one really knows how great is the exposure rate to this type of occurrence. Recently an incident happened which shows how easy it is to have a false sense of orientation. 

The flight was a long distance one over mountainous, European terrain. The forecast wind was badly in error, the actual wind being in the order of the 100 knot headwind instead of 20 knots, so the flight was uncertain of its ETA. Both ADF's were tuned and, although there was considerable snow static, identified on the destination station and the ILS was likewise used. Presently both ADF's reversed, indicating an overhead, and almost simultaneously the ILS needle changed quadrants, confirming the position. The pilot requested and was granted letdown clearance from his 14,000'

Please note that the language and terminology used in this collection reflects the context and culture of the time of its creation, and may include culturally sensitive information. As an historical document, its contents may be at odds with contemporary views and terminology. The information within this collection does not reflect the views of the Smithsonian Institution, but is available in its original form to facilitate research. For questions or comments regarding sensitive content, access, and use related to this collection, please contact