What happened
On 21 December 2010, a scheduled passenger flight operating a Boeing 737-8AS, registration EI-ENB, arrived at Kerry Airport from Stansted Airport. Following a routine landing, the crew applied reverse thrust to decelerate. During this process, a safety pilot noticed blue-tinted smoke entering the right side of the flight deck. Shortly thereafter, the cabin services supervisor reported a similar presence of smoke-like vapor throughout the passenger cabin.
As the aircraft taxied toward the ramp, the smoke became dense and acrid. The commander, prioritizing safety, ordered the crew to don oxygen masks and subsequently initiated an emergency evacuation. The engines were shut down, and all 170 passengers and 7 crew members exited the aircraft via the available slides and overwing exits. While the evacuation was completed in approximately 30 seconds, it was noted that many passengers attempted to carry hand baggage with them during the egress.
The investigation
The AAIU examined the aircraft and the airfield conditions following the incident. No mechanical defects or technical anomalies were discovered within the aircraft's systems. However, investigators found significant amounts of granular urea spread on the runway and taxiway, which had been used as an alternative anti-icing agent due to the exhaustion of standard de-icing fluids during a period of extreme cold.
Testing of the urea revealed that when heated, the substance produces an acrid, pungent odor and a greyish haze. The investigation also reviewed the cockpit voice recorder (CVR), noting that the recording ceased during the engine shutdown because the aircraft's electrical power source was lost. Additionally, the investigation looked into the behavior of passengers during the evacuation and the lack of prior notification regarding the use of urea on the movement area.
Findings
- The primary cause of the smoke was the ingestion of granular urea into the engines during the use of reverse thrust.
- A period of intense cold weather necessitated the use of urea as a runway anti-icing substitute after standard supplies were depleted.
- The flight crew had not been notified via official channels that urea was being utilized on the airfield.
- The evacuation was complicated by passengers attempting to retrieve carry-on luggage, which can impede flow rates and risk damage to emergency slides.
Safety action
- The Irish Aviation Authority should ensure airport operators notify pilots when urea is used for anti-icing via NOTAM or ATIS.
- EASA should implement requirements for CVRs to maintain power for a period following a loss of normal aircraft power.
- ICAO should develop guidance for cabin crew regarding passenger management of hand baggage during emergency evacuations.