ASN Wikibase Occurrence # 310308
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| Date: | Monday 21 May 2018 |
| Time: | 16:18 UTC |
| Type: |  Airbus A320-271N |
| Owner/operator: | IndiGo Airlines |
| Registration: | VT-ITW |
| MSN: | 7618 |
| Year of manufacture: | 2017 |
| Engine model: | Pratt & Whitney PW1127G-JM |
| Fatalities: | Fatalities: 0 / Occupants: |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Chennai ACC -
 India
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Visakhapatnam International Airport (VTZ/VOVZ) |
| Bangalore-Hindustan Airport (BLR/VOBG) | |
| Investigating agency: | AAIB India |
| Confidence Rating: |  Accident investigation report completed and information captured |
IndiGo Airlines flight 6E771, an Airbus A320-271N (VT-ITW), and an Indian Navy jet aircraft (callsign HK053) were involved in a serious airprox incident
HK053 had departed from Vizag for carrying out touch and go exercises at Vijaywada. At the time when incident occurred, flight HK053 was climbing to FL250 with Vizag control as destination and flight IGO647 was on the reciprocal track maintaining FL240.
Before HK053 got airbone from Vizag, Vizag ATC had coordinated estimate of HK053 as Vizag- Overhead Vijaywada – Vizag with outbound FL260 and inbound FL250. However, as per flight plan, HK053 was carrying out practice diversion to Vijayawada (including touch and go) and had requested Vijayawada Tower for a practice ILS approach for RWY 26. Vijayawada Tower had approved the practice ILS approach RWY 26 and thereafter coordinated with Chennai ACC for climb of HK053 to FL250.
HK053 was displayed on Controller Situation Data Display (SDD) as synthetic track based on flight plan data until 16:17:28 UTC. Thereafter, it was displayed as surveillance track on real time basis. After ILS approach practice on RWY 26 at Vijayawada, at 16:08 UTC, HK053 was climbing to FL250. As the separation (Vertical) between the two aircraft was reducing, the Chennai Automation System generated Mid Term Conflict Detection (MTCD) warning in Red on SDD between HK053 and IGO647. In addition, Airspace Warning (AS) was also displayed for
HK053 and IGO647.
The minimum vertical separation between these aircraft reduced to 200 feet while no horizontal separation existed thereby causing airprox incident with proximity categorization as ”A”. Evasive action was taken by both aircraft as per the command given for resolving the conflict.
The sectors UMM (North) and UMM (South) were combined and traffic density observed was medium to high. It was observed that surveillance controller after the incident was not responding to the call by IGO647, HK053 and IGO342 (relaying for IGO647), however, during that period, other aircraft were issued instructions. IGO647 did not return to the original clearance (FL240) once clear of conflict and maintained FL245 until cleared to climb to FL340
Probable Cause
IGO647 which was flying at FL240 came in very close proximity of HK053 resulting in generation of RA on both flights due to
- Oversight by Chennai Planning Controller of approval given to HK053 to climb to FL250.
- Lack of surveillance pickup of HK043 leading to loss of situational awareness of surveillance controller.
- Overlooking MTCD warning generated by Chennai Automation System by Surveillance Controller.
- High traffic density due to combining of UMN & UMS sectors.
Accident investigation:
 |
|
Sources:
AAIB India
History of this aircraft
Other occurrences involving this aircraft
| 3 January 2019 | VT-ITW | IndiGo Airlines | 0 | NE of Chennai Airport | |
min |
| Engine failure | ||||||
| 16 January 2020 | VT-ITW | IndiGo Airlines | 0 | near Pune | |
unk |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 11-Apr-2023 19:06 | harro | Added |
Corrections or additions? ... Edit this accident description
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