What happened
On 10 May 2007, an Embraer EMB-145EP, registration G-RJXA, was performing a scheduled passenger flight from Aberdeen to Manchester. Approximately four and a half minutes after takeoff, while climbing through FL116, the aircraft's Engine Indicating and Crew Alerting System (EICAS) issued a caution, followed by an autopilot disconnect warning. Simultaneously, the commander's Primary Flight Display (PFD), Multi Function Display (MFD), and EICAS screens went blank, and smoke began to emerge from the left side of the commander's seat.
Upon detecting an acrid smell and a smoky haze, the commander declared an in-flight emergency and initiated a return to Aberdeen. During the descent, the commander manually adjusted the pressurization control panel and took control of the aircraft as the co-pilot flew manually. The aircraft landed at Aberdeen within 15 minutes of the initial incident, and an evacuation was subsequently carried out.
The investigation
The AAIB investigation focused on the cause of the electronic failure and the crew's response to the smoke. Investigators found that the smoke was caused by the failure of the No 1 Integrated Avionics Computer (IC-600). Technical examination of the unit revealed that a ceramic capacitor on the power supply had failed in an 'open' state. This caused the 150 VDC supply line to overheat, damaging the power supply card and adjacent circuitry, which produced the smoke.
Regarding the crew's performance, the investigation noted that the pilots did not follow the Quick Reference Handbook (QRH) procedures. Specifically, the crew did not don oxygen masks or establish communications as required by the operator's manual. The commander also attempted a smoke evacuation checklist from memory rather than following the written instructions, and he failed to perform the necessary fault diagnosis for the blank displays.
Findings
- The smoke in the flight deck was caused by the failure of the No 1 IC-600 computer due to an overheating capacitor.
- The flight crew did not don oxygen masks or establish communications at the first sign of smoke, which potentially endangered the crew and passengers.
- The commander failed to complete the Display Failure/IC-600 failure checklist, which would have restored the primary flight displays.
- The crew's decision to perform checklists from memory rather than using the QRH increased the risk of error.
- The commander's decision to communicate with the cabin crew at a low altitude (300 ft) distracted the co-pilot during a critical phase of flight.
Safety action
Following the incident, the operator implemented a series of simulator exercises for flight crews, focusing on the procedures for donning oxygen masks and managing smoke or fumes in the flight deck.