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In my previous article I highlighted the faulty glideslope at Bengaluru International Airport (BIA) being a contributor to delays, especially in times of fog. Last Sunday January 24, 2009, BIA, again, experienced significant delays due to fog.
This issue has been hanging fire at Bengaluru International Airport since opening day.
I came across an article by Capt. A. Ranganathan, an Airline Instructor Pilot on Boeing 737 with a flying experience of 20,000 hrs, which explains the situation more technically, and with the right dose of humour.
To err is human but when an error is committed repeatedly, one must credit them with complete incompetence. They have proved that they are champions in “Bending it like Beckham”!
New Greenfield airports are constructed in Bangalore and Hyderabad. The runways are located in areas free of obstacles and the builders install PAPIs (Precision Approach Path Indicators) at a perfect 3° angle. PAPIs are mandatory equipment required by ICAO for airfields where airliner jets operate. These assist pilots to complete a precise landing in the touch down zone after they transition from an instrument approach. All the four runways, two in each city, had these installed at 3° angle.
The AAI installed the ILS (Instrument Landing System) for all the four runways. And they showed why they are great fans of the footballer. They bent the glide slope angles to 3.30° and 3.40°, instead of synchronising them with the 3° PAPIs. With this master-stroke, they killed the two airports from being capable of operating flights in CAT 2 and CAT 3 ILS conditions in fog. The recent diversions from Bangalore and Hyderabad, and the resultant air traffic congestion at Mumbai could have been avoided if the ILS Glide Slope had been less than 3.25° . The airport owners should have insisted on the AAI redoing the glide slopes. Instead, they bend the PAPI angles up to synchronise with the ILS! This is progressive thinking! Airports which should have functioned ‘24 x 365’ hours in a year are restricted to operations ONLY when the visibility is more than 550 metres,
High Glide Slope angles at Hyderabad and Bangalore. Photos: Naverus and Capt. A. Ranganathan
The implications do not stop there. All aircraft have a structural limit for their landing gear. The maximum rate of descent permitted is 600 feet per minute. A glide slope up to 3.25° will ensure a controlled flare and landing within this limit. Any higher angle will require a descent rate of 800 to 900FPM. A positive flare in the correct time is required. Any delay can result in a hard landing or a late touch down. These are a major threat while landing in heavy rain conditions. If the rain condition is accompanied by changing winds, especially tail winds, it becomes a dangerous recipe.
Read the full article here.
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