Rapid Cabin Altitude Rise in Fokker F28 over English Channel

Casualties unknown • Flight level 250 over the English Channel, GB

A passenger flight involving a Fokker F28 experienced a sudden loss of pressurisation and a rapid cabin altitude climb while over the English Channel.

What happened

On 29 October 2003, a Fokker F28 Mark 0100, registration G-BXWE, was operating a passenger flight from Heathrow at a flight level of 25,000 feet. While traversing the English Channel, the crew detected a hot odour emanating from the air conditioning vents. Simultaneously, the pack duct temperature rose sharply to 94°C, far exceeding the standard 17°C.

Following this temperature spike, the cabin altitude began to climb at an uncontrolled rate, estimated by the commander to be between 4,000 and 6,000 feet per minute. Despite attempts to manually adjust the pressurisation controls, the cabin altitude continued to rise, eventually reaching 15,500 feet. This triggered the automatic deployment of passenger oxygen masks. During the subsequent emergency descent, some passenger masks became entangled, though the crew and all 55 passengers remained uninjured.

The investigation

The investigation focused on the air conditioning system and recent maintenance activities. The aircraft had a history of various defects in both air conditioning packs throughout late 2003, including issues with temperature control and erratic pressurisation.

Investigators examined a recent maintenance entry known as a Carried Forward Defect (CFD). This entry, created three days prior to the incident, was found to be ambiguous. While the entry noted a defect in an electrical connector, its reference to the Minimum Equipment List (MEL) led the flight crew to believe that the second air conditioning pack was intentionally inoperative for the flight.

Technical analysis of the failure revealed that the temperature sensor ducting for the flight deck had become detached from its mounts. Furthermore, the investigation looked into the electrical connector pins that had been identified as being in poor condition.

Findings

  • The primary cause of the temperature spike and subsequent loss of pressurisation was a faulty temperature sensor and detached ducting.
  • An ambiguous maintenance record (CFD) led to a misunderstanding regarding the operational status of the aircraft's air conditioning packs.
  • The aircraft was dispatched with the understanding that pack 2 was inoperative, when in fact the issue was related to the electrical connector pins.
  • The rapid increase in cabin altitude was driven by the failure of the temperature control system to regulate the bleed air temperature.

Probable cause

The incident was caused by a malfunctioning temperature sensor and detached ducting, compounded by ambiguous maintenance documentation that led the crew to misinterpret the aircraft's air conditioning configuration.

Frequently asked questions

What happened in the 2003-10-29 FOKKER F28 MARK 0100 accident near Flight level 250 over the English Channel, GB?

A passenger flight involving a Fokker F28 experienced a sudden loss of pressurisation and a rapid cabin altitude climb while over the English Channel.

What aircraft was involved and where did it happen?

The accident on 2003-10-29 involved a FOKKER F28 MARK 0100, registration G-BXWE, at Flight level 250 over the English Channel, GB.

What was the probable cause of the accident?

The incident was caused by a malfunctioning temperature sensor and detached ducting, compounded by ambiguous maintenance documentation that led the crew to misinterpret the aircraft's air conditioning configuration.

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