Virgin Atlantic A346 near Halifax on Feb 23rd 2017, cabin pressure problems affect crew

Last Update: September 14, 2017 / 14:51:10 GMT/Zulu time

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Photo of Virgin Atlantic G-VGAS, Airbus A340-600 — Virgin Atlantic G-VGAS, Airbus A340-600 (Photo credit: Hawkwindzoo - Steve Walsh / Flickr / License: CC by-nd)

Incident Facts

Date of incident
Feb 23, 2017

Classification
Incident

Cause
Cabin pressure problems

Airline
Virgin Atlantic

Flight number
VS-9

Departure
London Heathrow, United Kingdom

Destination
New York JFK, United States

Aircraft Registration
G-VGAS

Aircraft Type
Airbus A340-600

ICAO Type Designator
A346

A Virgin Atlantic Airbus A340-600, registration G-VGAS performing flight VS-9 from London Heathrow,EN (UK) to New York JFK,NY (USA) with 198 passengers and 14 crew, was enroute at FL400 about 170nm southwest of Halifax,NS (Canada) when problems with the cabin pressure prompted the crew to descend the aircraft to FL240. The aircraft continued to New York for a safe landing about 65 minutes later.

The AAIB reported that a number of crew were temporarily affected when cabin pressure problems prompted a controlled descent. The occurrence was rated a serious incident and is being investigated by the AAIB.

On Sep 14th 2017 the AAIB released their bulletin concluding the probable cause was:

Data from the aircraft showed that there was a Cabin Pressure Controller 1 (CPC1) fault at the same time as the first CAB PR EXCESS CAB ALT warning. Engineers suspected that the CPC1 had failed in such a way as to drive the outflow valves open, thus allowing the cabin altitude to increase (the warning is triggered when the cabin altitude exceeds 9,550 ft).

On inspection, five components within the CPC were found to be defective due to wear but the failure mode suspected by the engineers was not identified conclusively.

The AAIB reported the aircraft was enroute at FL400 about 200nm northeast of Boston,MA (USA) when the "CAB PR EXCESS CAB ALT" message activated on the ECAM display, the pressurization displays showed no anomalies however. The excessive cabin altitude warning remained however, and both pilots as well as two members of the cabin crew believed to suffer symptoms of hypoxia. The flight crew therefore began a descent, at FL260 the warning extinguished. The crew decided to level off at FL250 and continued the flight to destination. About 30 minutes later the warning activated again, the indications of the cabin pressurization were still normal. Nonetheless the crew decided to descend further to 11,000 feet and landed at the destination without further incident.