Mangalore Air crash and Instrument Landing System

     As our principal Mr. Gilroy John Luiz is so particular in the personality of each student, all students are required to maintain a reasonable hair-cut and proper shaving always. Thus, having a hair cut twice a month became a habitual action. The next day of Mangalore air crash I went to a saloon to have my hair-cut. It was an evening. In my rural area, people usually join together either in some tea shops or saloons after their working hours. For them, discussing something with others is a good method of relieving fatigue and tension. When the barber began hair cutting, some people gathered there and started slandering others. In between somebody put the topic of air crash in front of them. Everybody’s attention turned into it. He was simply trying to shine in front of them. What ever he told them, was utterly foolishness. Before telling something, he should have read the news paper at least (in fact, he is a political leader)-I thought in my mind.

     During this time, some people had approached me with genuine doubts. They wanted to know about ILS (instrument landing system) mainly. As a student of aeronautics, I have the responsibility to answer their question. But, unfortunately, as I am not an avionics student, I couldn’t answer and make them understand completely. Here I am trying to explain about ILS which is said to be the main cause of that air crash.

     In our child hood, we used to play a game on which after a particular round we are supposed to play only in accordance with the guidance of other friends. Mishel obama once played the same game with children of Mumbai, when she visited India. In short, this is the main theory behind the instrument landing system. Landing of an aircraft, using instruments under zero visibility conditions. I shall explain it here without going into deep and using much technical words.

     During heavy fog condition or the pilot can’t see anything (what we call zero visibility), each aircraft has to be landed safely as directed by the instruments. This system enables the ATC to make the aircraft land in a particular runway at a particular time automatically. ILS includes two parts. Marker systems-outer marker (blue indication) which is at a distance of 3.9NM approx. from the Runway threshold, middle marker (yellow light) at a distance of 3500ft approx. and an inner marker (white light) at a distance of 1000ft. The second part is localizer antennas (that you can see in the above picture with yellow colour) and a Glide scope antenna. Suppose the aircraft is approaching an airport at night. When the aircraft passes the outer marker which is at a distance of 3.9 NM from the touch down point (runway threshold), the pilot gets a blue indication with a series of dashes in his cockpit. So the pilot can understand that his aircraft has reached so and so distance from the threshold. When the aircraft further moves and crosses the middle marker, pilot gets a yellow indication with a series of dots and dashes in the cockpit. Finally the aircraft reaches the inner marker which is near to the touch down point (approx.1000ft). What will happen? Pilot gets a series of dots and a white indication which tells the pilot that the aircraft is about to land. Next problem is-the aircraft has to maintain a correct angle before landing. Glide scope antennas takes this responsibility and provide the correct angle to the aircraft (while landing, nose will be up first. Hope you have seen it in films at least). The purpose of the localizer antenna is to give a direction to the pilot or rather aids the pilot to maintain a correct center line. Wind sac will be provided in the runway ends to indicate the direction of the wind. Aircraft  normally take off and land against the direction of the cross wind.
If something is not working, then the pilot will advance the throttle to initiate a missed approach and “go around” to land the aircraft in some other places.

About Mangalore crash

     The reason which is considered as the root cause of this tragedy is-hitting the aircraft in the glide scope antenna. The stability and control of the aircraft lost after that serious hitting and it fell in to the swire from the table-top runway. Actually that was a missed approach. The pilots were about to increase the engine power and fly from the runway threshold. I think they couldn’t land the aircraft in correct center line. Otherwise the possibility of hitting the wing with glide scope antenna would never occur. Nowadays we are using sophisticated radio communication equipments. Still a single human error will have to give a huge cost.

I am not an avionic student. What I have explained here may have some mistakes because we don’t have to study this portion. I gained only limited knowledge regarding avionics equipments which is from my electronic instructor commander Rajan Pillai sir.

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Sreeraj pathari
About2takeoff@gmail.com
sreerajpathari@gmail.com