What happened
On May 21, 2010, an Airbus A320-214, registration OH-LXL, operating a scheduled flight from Budapest to Helsinki, encountered a serious flight safety incident during its approach to runway 22L at Helsinki-Vantaa Airport. The flight was being conducted under visual flight rules in good weather conditions.
At approximately 1,300 feet, the captain initiated the stabilization process and instructed the co-pilot to set the flaps to position three and then to the full landing position. Although the co-pilot verbally acknowledged both commands, he instead retracted the flaps to the zero position. This error caused the aircraft's airspeed to drop to 157 knots, which was 14 knots below the minimum required speed for that configuration.
As the aircraft struggled to maintain speed, it sank significantly below the intended glidepath, dropping 600 feet compared to the expected 250-foot descent. Recognizing the unstable approach, the captain executed a go-around at approximately 700 feet. The aircraft subsequently completed a successful second approach and landed normally on runway 15.
The investigation
The investigation examined the cockpit voice recordings, flight data, and crew interviews. Investigators found that the crew was well-rested, the flight workload was normal, and all standard operating procedures (SOPs) were being followed prior to the error. The weather was clear with good visibility, though some convective activity caused minor turbulence that made maintaining speed slightly more difficult.
Analysis of the crew's performance focused on the nature of the error. The investigation determined that the co-pilot's action was an unintentional slip—a type of error where an automated or habitual physical movement overrides a conscious, controlled action. The investigation also noted that the crew performed a proper debriefing and filed an air safety report (ASR) following the event.
Findings
- The primary cause of the incident was the co-pilot's erroneous selection of the flap zero position instead of the commanded full landing configuration.
- A contributing factor was the routine nature of the flight; the high level of automation and repetitive tasks during a standard flight can lead to a lapse in concentration or the occurrence of habitual slips.
- The aircraft's Alpha/Speed Lock protection activated to prevent a stall, but the aircraft still suffered a significant loss of altitude due to the speed deficit.
Safety action
Based on the finding that the aircraft sank significantly below the glidepath at a low altitude, the investigators recommended that the operator update its Flight Operations Manual (OM-A). The recommendation specifies that all approaches, including daytime visual approaches, should be stabilized at a minimum altitude of 1,000 feet above the runway threshold to ensure sufficient obstacle clearance and approach stability.