9. Human factors in aviation
Human factors is a critical aspect of aviation safety, one that ICAO began to address more than a decade ago.
ICAO convened the first in a series of global symposia on flight safety and human factors in 1990. From the beginning, when the fist event was held in city known then as Leningrad, there was a conviction that international aviation could make enormous progress in improving safety through the application of human factors knowledge.
The first symposium was a turning point and the stage for following meetings in US, New Zeland and finally in Chile in 1999. There have been encouraging developments since 1990, but we still have challenges to pursue: after the Leningrad symposium, human error remains a significant safety concern.
The purpose of the worldwide symposia and 10 regional seminars which were held in past decade was to increase the awareness of States, industry and organizations in all ICAO regions about the importance of human factors. The ongoing implementation of the ICAO communication, navigation, surveillance and air traffic management (CNS/ATM) systems concept has introduced new challenges, and also new possibilities for human factors. The reason the community must respond to is, of course, to ensure that civil aviation continues to achieve its ultimate goal: the safe and efficient transportation of passengers and goods.
The ICAO flight safety and human factors programme is safety-oriented and operationally relevant. Moreover, it is practical since it must deal with real problems in a real world. Through the programme, ICAO has provided the aviation community with the means and tools to anticipate human error and contain its negative consequences in the operational environment. Furthermore, ICAO’s efforts are aimed at the system – not individual.
The global aviation safety plan (GASP) was developed by the ICAO Air Navigation Commission in 1997 and subsequently approved by the ICAO Council and endorsed by the ICAO Assembly. GASP was designed to coordinate and provide a common direction to the efforts of States and the aviation industry to the extent possible in safety matters. It is a tool that allows ICAO to focus resources and set priorities giving emphasis to those activities that will contribute the most to enhancing safety. Therefore the flight safety and human factors programme is among the six major activities that comprise the plan.
10. VISUAL AIDS FOR NAVIGATION, + ILS
Additional visual aids to navigation consist of markings on the aerodromes. These markings comprise single lines or rows of lines which, for the pilot, are very important for holding positions, runway thresholds, the runway centre lines, the sides of the runways, etc.
However, at night or during poor visibility by day, lights are required. To be effective lights must be adequate intensity. At certain aerodromes the controller can vary the intensity of some of the lights so that they can be reduced not to blind the pilot and strong enough so that he can see them at bad weather. The first lights a pilot sees on approach is generally the aerodrome beacon. It many rotate and can be seen at great distance. There might be an identification beacon which shows green flashes of light. Red lights, the usual danger signal, warn pilots of the obstacles such as hangars and other high buildings, telephone poles, etc. Runway edge lights identify the runway and approach lights assist the pilot to align himself with the runway.
Lights may also be used to provide a glide path similar to what ILS provide electronically. The Visual Approach Slope Indicator System (VASIS) is a beam of light having a white colour in its upper part and red colour in its lower part.
A pilot of an aeroplane during an approach will:
a) when above the approach slope, see the lights to be white in colour;
b) when on the approach slope, see the lights to be pink in colour; and
c) when below the approach slope, see the lights to be red in colour.
By the reference to VASIS, combined with ILS, the pilot can bring an aircraft down safely almost to touchdown by day or night.
After landing, he follows the blue taxi lights along the taxiway to the apron and the service areas.
At the service area a marshaller, with illuminates wands, direct the aircraft with signals to its proper position for unloading and, finally, signals pilot to cut the engines.
ILS – Instrument Landing System.
The ILS is designed to provide an approach path for exact alignment and descent of an aircraft on final approach to a runway.
The ground equipment consist of two highly directional transmitting systems along with three (or fewer) marker beacons. The directional transmitter are known as the localizer and glide path transmitters.
The system may be divided functionally into three paths: guidance information – localizer, glide path range information – marker beacons, visual information – approach lights, touchdown and centerline lights, runway lights.
the localizer transmitter, operating on one of the twenty ILS channels emits signals which provide the pilot with course guidance to the runway centerline.
The UHF glide path transmitter, operating on one of the twenty ILS channels radiates the signals principally in the direction of the final approach.
Ordinarily, there are two marker beacons associated with ILS; the outer marker and middle marker. However, some locations may employ a third beacon – the inner marker.
The outer marker normally indicates a position at which an aircraft at the appropriate altitude on the localizer course will intercept the ILS glide path.
The middle marker indicates the position at which an aircraft is approximately 3500 feet from the landing threshold. This will also be the position at which an aircraft on the glide path will be at an altitude of approximately 200 feet above the elevation of the touchdown zone.
The inner marker will indicate a point in which an aircraft is at designated decision height on the glide path between the middle marker and landing threshold.