On 28 April 1999, a BAe 146-300 being operated by Aer Lingus on a scheduled passenger flight from Birmingham to Dublin began its take off from Runway 33 in normal daylight visibility without ATC clearance just prior to the touchdown of a PIPER PA-38 Tomahawk on the intersecting runway 06. Collision was very narrowly avoided after the Controller intervened and the BAe 146 rejected its take off but was unable to stop before the intersection where the now stationary PA38 was positioned off the runway 33 centreline. As the BAe 146 stopped, the aircraft commander transmitted “did we hit him” to which a negative reply was given by the Controller.
A Field Investigation was carried out by the UK AAIB. It noted that First Officer line training had been taking place on the BAe 146 with the Training Captain occupying the left hand seat and a Safety Pilot occupying the centrally-positioned supernumerary seat. The First Officer was acting as PF under supervision but since he was without a nose gear steering tiller, the Captain was responsible for the directional control of the aircraft until rudder steering became effective whilst reverting to PM once control had been handed over. The Investigation was told that the aircraft commander believed that the ATC communication about the post take off frequency change “included a take off clearance” although there was no read back of such a clearance. The trainee First Officer was reportedly preoccupied with the setting of the autothrottle system and the Safety Pilot apparently had an intermittent Station Box. The Captain commenced the take off but abandoned it prior to passing control to the co pilot because he heard an indistinct ATC transmission with his callsign which led him to “assume there to be a problem”. Shortly afterwards, he saw the PA38 and, although he attempted to stop before the intersection, this did not happen and the left wing of the BAe 146 passed over the right wing of the PA 38. The PA38 was found to have been on an instructional detail and had been issued with a landing clearance. When the Instructor, who had been aware of the 146 lined up on the other runway for departure, heard the Controller instructing the BAe146 to ‘hold position’, he looked to his right and saw the same aircraft approaching the intersection ahead. He took control from the student and applied maximum braking plus a 90° left turn as instructed by the Controller.
The Investigation confirmed that the BAe 146 had begun the take off without a clearance and noted that “as with the majority of incidents, this occurrence was the result of an accumulation of factors”, the most significant of which was the unexplained perception of the BAe146 aircraft commander that a take-off clearance had actually been given, despite the fact that it was not included in his read back of the departure instruction. The Investigation concluded that “this alone denied the controller an opportunity to correct the error. The controller's subsequent transmissions to both aircraft were timely in averting a more serious incident.”
The full UK AAIB Report of the Investigation, which did not contain any Safety Recommendations, was published on 9 September 1999 and may be seen at the SKYbrary bookshelf: AAIB Bulletin No: 9/99 Ref: EW/C99/4/4
Note that the illustration referred to in the text of the Report as “Figure 1” is not included in the document at source and so is missing from the SKYbrary copy of the Report too.