Kolkata: Over the past fortnight, over a dozen incoming flights to Kolkata have abandoned approach and pulled out at the last minute. In each instance, the pilot complained of malfunction in a critical visual landing guidance system installed at the southern end of the secondary runway. But with airport authorities insisting all is well despite a flurry of complaints, directorate general of civil aviation (DGCA) has asked Airports Authority of India (AAI) to get the precision approach path indicator (PAPI) recalibrated.
According to sources, the problem surfaced around two weeks ago when the primary runway was shut down for routine maintenance work. The pilot of a private airline, who was directed to approach the secondary runway from the south, veered away after the readings on the distance measuring equipment (DME) failed to match the indicators on PAPI. While DME tells pilot the distance between the aircraft and the runway, PAPI is a visual reference for the pilot to know the position of the aircraft relative to the guideslope or descent coordinate of the runway.
When other pilots also reported similar aberration in PAPI, the ATC shifted operations to the primary runway, shutting the secondary landing strip. While all landing strips have PAPI, the instrument becomes even more critical when there is no ILS.
11/11/12 Subhro Niyogi/Times of India
