What happened
On 7 March 2016, at approximately 10:07 UTC, a runway incursion occurred at Basel-Mulhouse airport involving two commercial aircraft. The first aircraft, a Dornier 328 registered HB-AEO operated by SkyWork, was cleared for takeoff from runway 15 via the GOLF intersection. Simultaneously, an Embraer 190 registered PH-EXB operated by KLM Cityhopper was taxiing toward runway 33 via taxiway DELTA.
While the crew of the Embraer 190 was being transferred from ground to tower frequency, they received a hold short instruction for runway 33. However, the crew mistakenly read back "Line up and wait runway 33 DELTA." The air traffic controller did not correct this erroneous read-back. Convinced that runway 33 was the active runway, the crew of the Embraer 190 entered the runway. At that moment, the Dornier 328 was performing its takeoff roll on the same runway surface (using the 15/33 configuration). The two aircraft crossed paths with a vertical separation of only 380 feet. The incursion was only detected by the tower controller after the Embraert 190 had already entered the runway.
The investigation
The BEA investigation examined cockpit voice recorder data, flight parameter recorders, and interviews with both flight crews and air traffic controllers. The investigation focused on the communication loop between the pilots and the tower, the use of non-standard phraseology, and the situational awareness of all parties involved. The investigators also reviewed the airport's ground movement display system and the impact of cockpit distractions.
Findings
- The primary cause was an undetected erroneous read-back by the Embraer 190 crew, which the air traffic controller failed to correct.
- The crew of the Embraer 190 suffered from an inaccurate perception of the active runway, likely due to confirmation bias and the fact that they were not on the tower frequency when the takeoff clearance for the Dornier 328 was issued.
- Contributing factors included cockpit distractions caused by a cabin crew member sitting in the jumpseat and the high workload of the controller, who was simultaneously managing a VFR aircraft and another IFR departure.
- The use of a short taxiway left the crew with very little time to establish situational awareness before reaching the runway intersection.
- The controller's failure to intervene during the incorrect read-back allowed the misundertystanding to persist.