What happened
On 23 November 2004, a Boeing 757-3CQ, registration G-JMAA, was conducting a passenger flight from Antalya, Turkey, to Manchester International Airport. Prior to arrival, the crew received weather information indicating that Low Visibility Procedures (LVPs) were in effect due to poor visibility. Following company policy for planned automatic landings, the crew prepared for a Category 3A automatic landing using the Instrument Landing System (ILS).
As the aircraft approached the runway, the crew became aware that weather conditions were improving. However, during the final stages of the approach, the aircraft experienced a sudden movement. At approximately 30 feet above the ground, the aircraft rolled unexpectedly to the right. The commander immediately disconnected the autopilots and performed a manual landing to maintain control. There were no injuries and no damage to the aircraft.
The investigation
The investigation examined flight data from the aircraft's Flight Data Recorder (FDR) and radio transmissions from Manchester Airport Air Traffic Control (ATC). While the Surface Movement Radar and Cockpit Voice Recorder data had been overwritten, the FDR provided critical insights into the aircraft's behavior.
Investigators looked into the communication chain at Manchester Airport, specifically regarding how the cancellation of LVPs was relayed to pilots. It was discovered that while the decision to cease LVP operations had been made, the information was not effectively communicated to the crew of the G-JCLMA during a period of controller handovers and staff movement between operational positions.
Findings
- The aircraft's flight path was disrupted by erroneous localiser deviation signals.
- These signals were caused by temporary interference from a departing Embraer 145 aircraft, which took off immediately before the Boeing 757's landing.
- The FDR confirmed that the localiser signal remained steady until the aircraft descended below 50 feet, at which point the interference caused the autopilots to deviate from the correct path.
- A lack of recent practice in managing the transition into and out of LVP status contributed to confusion within the ATC unit.
- During a controller handover, the updated status of the LVPs was not passed to the approaching flight crew.
Safety action
Following the incident, the aircraft operator updated its Operations Manual to provide clearer guidance for pilots regarding LVP operations and automatic landings. Additionally, NATS implemented changes at Manchester Airport, including the introduction of an 'LVP Action List' and the staggering of controller handover times to prevent information loss.