Airprox Serious incident Boeing 777-236ER G-YMMD, Sunday 5 June 2022

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Date:	Sunday 5 June 2022
Time:
Type:	Boeing 777-236ER
Owner/operator:	British Airways
Registration:	G-YMMD
MSN:	30305/269
Year of manufacture:	2000
Fatalities:	Fatalities: 0 / Occupants: 158
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	near Peshawar VOR - Pakistan
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	London-Heathrow Airport (LHR/EGLL)
Destination airport:	Islamabad International Airport (ISB/OPIS)
Investigating agency:	BASI Pakistan
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Aero Nomad Airlines flight 4506, an Airbus A320 (EX32009) and British Airways flight BA2261, a Boeing 777-236ER (G-YMMD) were involved in a serious airprox incident in Pakistani airspace.

When ANK4506 was 5 Nautical Miles (NM) North of Peshawar (PS) VOR climbing out of FL318 for FL320, it encountered a Traffic alert and Collision Avoidance System – Resolution Advisory (TCAS-RA) with reciprocal traffic BAW2261 which was descending from FL390 to FL330 passing FL332 at the time of incident.
ANK4506 descended from FL318 to FL315 on TCAS-RA. BAW2261 did not report TCAS-RA however, it followed TCAS-RA command to level off at FL330. Both aircraft had traffic information regarding each other.

Cause
1. Activation of TCAS – RA (MAC – Mid Air Collision) due high Rate of Descend by BAW2261.

Contributory Factors
1. Incorrectly transmitted previously set QNH pressure by the ANK4506 transponder which was not monitored by ATC Controllers as well as flight crew

Accident investigation: