Pilots weave through 300 obstacles to land in Chennai

CHENNAI: Pilots flying into the city airport need to watch out for more than 300 obstacles on the approach paths of the two runways, according to terrain and obstacle data released by Airports Authority of India (AAI). These are buildings, high mast lamps, electric poles, mobile phone towers, water tanks and dish antennas atop buildings and hoardings.

In addition to the buildings, the metro rail’s elevated line and stations also pose a risk. The electric overhead cable poles of the metro rail line from airport to Alandur, Nanganallur metro station, canopy over metro rail lines from airport and St Thomas Mount to Alandur station and the Alandur metro rail station itself violate permissible height limit for structures around the airport.

There are 46 obstacles on the approach path to the Guindy-end of the main runway, 154 at the Pallavaram-end and 120 at the Manapakkam-end of the second runway.

The map shows that the metro rail elevated line with a canopy over it from St Thomas Mount to Alandur is 40.3 metres high, while the permissible limit at the location is only 37.5m. The Nanganallur metro rail station is also an obstacle, as the elevation of the line with the train will exceed the limit by 10.6m. The stations and the elevated line fall in the approach path of planes coming in to land at the Guindy-end of the main runway.

AAI recently released electronic Terrain and Obstacle Data (eTOD) to help airlines and pilots understand obstacles likely to be faced while making flight plans and while descending into the airport.

Air safety expert and former pilot Mohan Ranganathan said the permissible height in airspace on the approach path to a runway is decided based on the assumption that if a plane loses one engine, it will require an obstacle-free space to glide down safely to the runway.

Planes are between 76m and 91m high as they glide down while coming in to land.

“Pilots will be able to see the buildings and trees but lone masts and flood light masts are riskier because they cannot be spotted,” said Mohan. A pilot said, “The obstacles are available on the aviation charts. We ensure that the highest obstacle is cleared so that we will be safe during landing .”

Buildings around the airport need to be constructed only after obtaining no-objection certificates. But there are violations after they are built. In many cases, the buildings stick to the height limit but additions like water tanks, pipes, mobile phone towers and dishes atop them are the infringements.

“AAI has been requesting the local body to demolish such additions, but in vain. A few under-construction buildings which have NoCs are not following the rules,” said an airport official.

Ranganathan said, “The Bombay and Delhi high courts have issued orders to demolish buildings that are obstacles to flights near the airports. May be, we need a similar order here”.