What happened
On May 3, 2004, at approximately 21:39 local time, a serious runway incursion occurred at Munich Airport involving two commercial aircraft. An ATR 42-500 (AT 45) was positioned at the CAT-I holding point on taxiway B4, preparing for a flight to Villafranca. At the same time, a Boeag 737-300 (B 733) was on short final approach to runway 08R.
Following the departure of an Airbus A321, the air traffic controller issued a conditional clearance to the crew of the ATR 42-500, instructing them to line up on runway 08R "behind the next landing aircraft." As the Boeing 737-300 crossed the runway threshold, the ATR 42-500 proceeded to enter the active runway. The crew of the Boeing 737-300 identified the encroaching aircraft immediately after touchdown and performed an evasive maneuver, passing the ATR 42-500 on the right side with only a few meters of separation. There were no fatalities and no injuries to the passengers or crew, and no damage was sustained by either aircraft.
The investigation
The BFU investigation focused on the communication between the air traffic controller and the aircraft crews, as well as the functionality of airport surveillance systems. The investigation examined the specific wording of the conditional clearance and the visibility of the approach sector from the taxiway holding point. Investigators also reviewed the operational procedures of Deutsche Flugsicherung GmbH (DFS) regarding the use of conditional clearances and the reliability of the Airport Surface Movement Radar (ASMR) alarm functions.
Findings
Several factors contributed to the near-collision:
- The communication regarding the conditional clearance was misleading, leading the crew of the ATR 42-500 to enter the runway while it was occupied.
- The crew of the ATR 42-500 had limited visibility of the final approach sector from their position on taxiway B4.
- The Runway Incursion Monitoring (RIM) alarm function of the ASMR was deactivated because the system was considered unreliable due to frequent false alarms.
- The regulatory procedures for issuing conditional clearances in the DFS manual were neither comprehensive nor precise.
- The use of taxiway B4 for lining up for departures involved a lack of specific risk assessment for such maneuvers.
Safety action
- The DFS was advised to revise the procedures for conditional clearances in the Air Traffic Control Operational Order to ensure clearer and more unambiguous instructions.
- A recommendation was made to ensure that airport surface surveillance systems with conflict detection capabilities are reliable and functional.