Mon, 24 May 2010 09:40:44 GMT

Approach radar could have averted Mangalore tragedy

New Delhi: What Mangalore airport sorely missed on Saturday morning was an “approach radar”.

Initial investigations have found that the ill-fated AI Express Boeing 737-800 aircraft, which had locked in with the Instrument Landing System (ILS) at 6 am, was "high on approach" and was not properly aligned to the glide path. This led to the plane overshooting the touchdown zone, which caused the crash.

Had an approach radar been available, the air traffic controller could have seen this and alerted the commander.

The pilots would probably have also noticed the error themselves¿a fact that can be known only after the black box is decoded¿but the approach radar serves as an important back-up.

While the primary task of this radar is to monitor all approaching aircraft up to 50 nautical miles around the airport, it also has an ILS panel which allows the ATC to monitor the progress of a plane once it establishes contact with the ILS.

In bigger airports such as Delhi and Mumbai, ATC controllers routinely warn pilots if they err on the glide path. It is also able to indicate the speed of the aircraft at the time of landing.

But none of this was possible in Mangalore and the pilots were very much on their own after locking in with the ILS. If prompted by the ATC, the pilot could have considered taking another round before landing but on this occasion, he went by his own judgment.

By late evening, authoritative sources said all indications pointed to a "human error". Snatches of the last few bits of the conversation start with the ATC first giving landing clearance: "Cleared for arc ILS approach runway 24."

Flight commander Zlatko Glusica confirms at around 6 am: "Established on ILS runway 24". ATC reconfirms: "Clear to land runway 24."

The flight touches down at 6-02 am, a good 2,000 feet into the runway, which meant that the pilot had just about 6,000 feet more to bring the aircraft to a halt.

Since the plane has to make a complete u-turn at the end of the runway and taxi back to the parking bay, the ATC sends out a routine message soon after the touch down.

"Backtrack runway 24" was the last message to Air India Express flight 812 from Dubai to Mangalore with 166 persons, including crew, on board.

Personnel at the air traffic tower looked out of their windows when there was no response from Glusica and within minutes saw a plume of smoke at a distance. India's first major air crash in over a decade had occurred.

Turning the clock back, sources said, the error possibly happened in those two minutes on the ILS when the plane went high on approach and did not align itself accurately on the glide path.

As a result, the touchdown went off track. In this case, the ATC was totally in the dark due to absence of an approach radar and could be of no assistance.

Usually, there are two criteria followed to deploy approach radars¿congestion and topography. It is now being said that Mangalore surely qualified on the second count because it has table-top runway built by connecting two hills.

While the new runway is 2,450 metres (about 8,038 feet), it has a relatively less spillover area of 90 metres and then a steep valley into which the plane finally crashed killing 158 persons.

Glusica, the 55-year-old Serbian-origin flight commander who is now a British national, had clocked 10,200 hours of which 2,770 hours were on the Boeing 737-800 as a commander.

But this was his first flight after 24 days of leave. Rules require a route check on the pilot only if he has been out of action for 50 days. He had landed in Mangalore 19 times, but his last flight to this relatively "tricky airport" was back in November 2009.

His co-pilot, HS Ahluwalia had flown last on May 17 but during landing and take-offs, it is mandatory for the commander to be on the controls. The duo had flown this flight to Dubai from Mangalore and were on the return leg when the crash occurred.

The narrative so far is that the flight was high on approach and also at a higher speed. After touchdown, it zipped across the runway and the pilot tried to apply emergency brakes, which could have caused the tyres to burst.

The commander also appeared to steer the plane to the left but in doing so, the right flap hit the ILS gear next to the runway and was badly damaged.

The plane went out of control, skid across the perimeter walls and fell into the valley. The fuselage broke just before the fall and possibly, some of the survivors managed to move out of the aircraft at that point, after which the plane caught fire.

This, sources pointed out is quite similar to what happened with an American Airlines flight AA331, also a Boeing 737-800, last December when it landed at Kingston, Jamaica, amid a rainstorm.

There again, the plane overshot the touchdown zone and landed 4,000 feet into the runway which was 8,900-feet long. But fortunately for the passengers, the plane skidded across the runway, on to a road and then came to rest on a beach. As a result, all 148 passengers and eight crew members survived.

Incidentally, the last accident in Mangalore airport itself on August 18, 1981, was quite similar. An Indian Airlines operated HAL-748-224 with 26 people on board, including crew, overshot the runway, nosed over into the valley but came to rest against two boulders with the nosegear collapsed.

That aircraft too had landed half way down what is now the old runway, which is much shorter. All 26 on board survived.

This time, however, the plane fell into a valley and the consequences were far more tragic.

Source: Indian Express

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