Friday, January 21, 2022

Is the ATC responsible for the near mid-air collision over Bengaluru airport?

In October 2019, the Airports Authority of India (AAI) informed stakeholders (airlines, air navigation service providers, the airline regulator, and so on) of the commissioning of a new runway at Bengaluru’s Kempegowda International Airport (KIA) south of the existing runway. The two runways were given the nomenclature RWY 09L/27R (also known as the north runway) and RWY 09R/27L (south runway). The first flight from the newly commissioned runway took off in December 2019. Even today, the KIA has the singular distinction of being the only airport in South India that operates parallel runways.

But on the morning of January 7 in a strange turn of events that had the potential to become dangerously fatal for nearly 430 passengers and crew of two IndiGo aircraft, the Air Traffic Control (ATC) at KIA cleared IndiGo flight 6E-455 bound for Kolkata and IndiGo flight 6E-246 bound for Bhubaneswar for take-off almost simultaneously from KIA’s parallel runways. The two Airbus A320s, prima facie, were involved in an aircraft proximity (airprox) occurrence, with a high risk of a “breach of separation”, as they took off from KIA’s parallel runways. It was left to the alertness of an approach radar controller who, on noticing the trajectory or flight path proximity of the two aircraft, alerted the air crew.

According to sources at KIA, both aircraft flew at the same speed and climb rate right until they reached around 3,000 feet before the radar controller’s action resulted in them veering away from each other. Officials also disclosed that if the pilots had not initiated preventive action, the two airplanes’ flight path might have merged into a single point at around 7,000 feet, an altitude which would have been reached in no time since the two A320s were climbing at a rate of approximately 2,000 feet per minute.

The Directorate General of Civil Aviation (DGCA), India’s statutory body for the regulation of civil aviation in India, has opened an investigation into the incident.

Though the pilots said that the Traffic Alert and Collision Avoidance System (TCAS) would have been activated and that there was no need for unnecessarily panic over the incident, the Air Traffic Control’s action in clearing both aircraft for simultaneous take off was illegal and unsafe and contravenes several of AAI’s regulations.

The AAI’s Manual of Air Traffic Services Part II, dated May 10, 2021, clearly states that when both runways (RWY) are available, the operations shall be in segregated mode wherein simultaneous operations on parallel runways are permitted, but with one runway being used for approaches and landings, and one runway being used for departures and take-offs. The AAI Manual of Air Traffic Services Part II, as part of the General Conditions, unambiguously states that the following conditions shall be adhered to: “No simultaneous departures from RWY 09R/RWY 09L (south runway/north runway) shall be permitted during segregated mode of operations or during change of modes. Similarly, no simultaneous departures from RWY 27R/RWY27L (north runway/south runway) shall be permitted during segregated mode of operations or during change of modes.”

The Manual of Air Traffic Services Part II goes on to further state: “No mixed mode of operations is permitted”. What occurred on January 7 was neither a segregated mode or a single mode. It was clearly a mixed mode, which is prohibited.

The AAI’s Manual of Air Traffic Services Part II also states that the control tower (TWR) handling arrivals shall inform the tower handling departures regarding “any missed approach/discontinued approach by arrivals”. States the manual: “During Low Visibility Operations Plan (LVOP) when segregated mode of operation is in progress on 09 mode and runway visual range (RVR) falls below 550m, tower one (TWR1) shall co-ordinate with TWR2 for those departures which have already joined Taxiway P/Q for South runway to depart from RWY 09R till RVR falls below 350m. TWR1 shall positively confirm from TWR2 that there are no further departures from RWY 09R [south runway] before allowing departures from RWY 09L. TWR2 shall positively confirm from TWR1 that there are no further departures from RWY09L [north runway] before allowing departures from RWY09R before reverting back to segregated mode of operations.”

Hence, not only is mixed mode not permitted, even in the case of LVOPs, segregated mode operations must first cease before single mode is activated.

20/01/22 Ravi Sharma/Frontline

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