What happened
On 29 May 2009, a Boeing 757-200, registration C-GTBB, was operating a charter flight from Sharm-el-Sheikh, Egypt, to Dublin Airport. Shortly after touching down on Runway 10, the flight crew alerted Air Traffic Control (ATC) to the presence of ground equipment positioned near the runway edge lighting. The crew specifically identified the object as a lone tractor lawnmower.
The investigation
Investigators determined that a small, ride-on grass mower was traveling eastward along the runway edge at the time of the aircraft's arrival. The mower was part of a multi-vehicle grass-cutting operation that had been ordered to stand down by ATC at 01:47 hrs because of declining visibility. At 01:49 hrs, ATC informed the incoming flight of fog conditions with visibility reduced to 800 meters.
The investigation found that the mower lacked both a flashing beacon and rear lighting. Furthermore, the vehicle was not equipped with an airband radio, meaning the driver could not monitor tower communications. Consequently, the driver was unaware of the approaching aircraft and did not see the plane before it passed. It is believed the starboard wing of the BoeCT 757-200 likely passed directly over the mower during the landing roll.
While the Advanced Surface Movements Guidance and Control System (ASMGCS) was still in its commissioning phase and not yet active in the Control Tower, test recordings of the system showed a target representing the mower. The system's recorded data also indicated that it had generated advance-warning symbols to signal a potential conflict between the mower and the landing aircraft.