ASN Wikibase Occurrence # 318263
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Friday 9 June 2017 |
| Time: | 15:16 UTC |
| Type: |  Airbus A320-214 |
| Owner/operator: | GoAir |
| Registration: | VT-WAK |
| MSN: | 3900 |
| Year of manufacture: | 2009 |
| Engine model: | CFMI CFM56-5B4/P |
| Fatalities: | Fatalities: 0 / Occupants: 182 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | EMRAK Hold -
 India
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Delhi-Indira Gandhi International Airport (DEL/VIDP) |
| Pune-Lohegaon Airport (PNQ/VAPO) | |
| Investigating agency: | AAIB India |
| Confidence Rating: |  Information verified through data from accident investigation authorities |
GoAir flight GOW171, an Airbus A320-214 (VT-WAK), and Jet Airways flight JAI392, a Boeing 737-800 (VT-JFM), were involved in a serious airprox incident.
Flight JAI392 from Shamshabad to Mumbai was given Standard Arrival Route (STAR) EMRAK1A and was holding over EMRAK hold and descending initially to FL200 and subsequently level FL190, FL180 and FL160.
Flight, GOW171 from Delhi to Pune came in contact with Mumbai Lower Area Control (LAC) and was given descent instructions to FL210 initially. When GOW171 requested for further descent, the LAC Controller instructed GOW171 to "Standby for descent due Traffic".
The automation system generated a Predicted Conflict Warning (PCW) for GOW171 and JAI392. The LAC Controller instructed GOW171 "to maintain flight level FL210 on reaching".
Again the automation system generated PCW for JAI392 and GOW171, to which the LAC Controller again asked GOW171 "Maintain level 210 on reaching due traffic." GOW171 was advised to descend to flight level FL200 and subsequently to flight level FL100, which was read
back by the crew of GOW171.
The wrong descent instruction to GOW171 to FL100 (which was above JAI392 and with higher rate of descend) by the LAC (Radar) Controller and loss of situational awareness of the crew of GOW171, as to the traffic (JAI392) below it, led to breach of standard separation. The crew of GOW171 failed to appreciate the step descend being given to them and immediately accepted level FL100 given by LAC Controller. The crew of GOW171 could have clarified from LAC Controller "Confirm FL100" or "Confirm Clear of Traffic now" as the lower level for Pune is FL120 and LAC Controller normally releases the aircraft to Pune above Flight Level FL120.
Both the aircraft reported getting a TCAS RA and followed the RA. The lateral separation between GOW171 and JAI392 was reduced to 2.8 NM when the vertical separation was just 100 feet as against the standard lateral separation of 10 Nm and standard vertical separation of 1000 feet.
Thereafter the flights were uneventful.
Probable Cause
1 Issuance of descend clearance to flight level FL100 to GOW171 inadvertently through the level of other aircraft i.e. JAI392 (passing FL178 for FL160 in EMRAK hold).
Contributory Factors
1 GO Air Crew’s failure to analyze the traffic scenario and accept descend below FL200 (without confirming from ATC “Confirm Clear of Traffic” and/or Confirm FL100.” as they were continuously being given step descend and were advised twice of the Traffic by the
Controller after getting Predicted Conflict Warning) could be a major Contributory Factor.
2 The traffic density, proficiency of Controller coupled with one Radar Controller manning the Lower Area Control (LAC) with Jurisdiction from FL 250 to FL 150 and keeping Surveillance over 05 (five) Holds simultaneously could be another contributory factor.
Accident investigation:
 |
|
Sources:
AAIB India
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 22-Jul-2023 06:40 | harro | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation