On 12 January 2006, a Boeing 747-200F being operated by Air China on a cargo flight from Beijing to Frankfurt made a night landing on runway 07R at destination and then taxiied in normal ground visibility across runway 07L in front of an Aer Lingus Airbus A320-200 which was landing after operating a scheduled passenger flight from Dublin. The landing aircraft increased braking upon sighting the 747, which had completed its crossing of the runway before the A320 reached its crossing point.
The incident was investigated by the Bundesstelle für Flugunfalluntersuchung (Germany) (BFU) Germany. Recordings of radar and communications were available to assist the investigation but the CVR and FDR recordings were not available from either aircraft. It was established that the 747 had been cleared to taxi via taxiway G to hold short of runway 07L. Because of an incorrect reference to taxiway H in the otherwise correct first read back, the controller had repeated the clearance to hold short of runway 07L on taxiway G but when this had been read back as a clearance to cross runway 07L, the error had not been detected and the controller involved had gone on to issue a landing clearance to the A320.
The A320 crew, which consisted of a Training Captain supervising a Captain undergoing line training and new to the aircraft type, reported having touched down in the Touch Down Zone (TDZ)of the 4000 metre long runway with autobrake set to low and normal reverse thrust used. As their speed had reduced below 100 kts, the crew saw that the 747 had entered and was crossing the runway further down at about 2500 metres along the runway. They had increased braking and subsequently reported the presence of the other aircraft to the controller, who had not noticed the incursion, before clearing the runway to the left onto taxiway G behind the 747.
It was surmised that the B747 crew could not have noticed the landing clearance given to the A320 and its conflict with what they believed to be their clearance to taxi across the same runway. In a prevailing visibility of 4800 metres, it was considered that the opportunity for visual contact between the two aircraft was not compromised. It was noted that as taxiway G crossed runway 07L at an angle of about 56°, any sighting of the A320 would have been confined to the pilot seated on the left hand side.
It was considered that the fact that the A320 had needed considerably less deceleration distance than that needed to remain clear of the intersection where the 747 was crossing had led to the conflict occurring “in a far less critical area (than) would have been the case in any other imaginable combination”
It was noted that Surface Movement Radar was available and that it had shown that the separation between the two aircraft whilst both were on the runway had been about 800 metres. It was also noted that the relevant warning system, Runway Incursion Monitoring (RIM) which would have provided a visual alert (RIM-Alert) on the radar screen as well as an aural alert, had been deactivated in accordance with a valid instruction issued because of the incidence of "frequent false alarms". In accordance with prevailing Cat 1 procedures, all stop bars were unlit.
The formal Conclusion of the Investigation was that:
“This serious incident occurred because of a misunderstanding in communications between the Tower and the B747 crew, as a result of which the B747 crossed the runway on which another aircraft had been cleared to land.”
One Safety Recommendation was made as a result of the investigation:
- that the Deutsche Flugsicherung (DFS) air traffic control company should ensure that airport ground movement monitoring systems equipped with conflict recognition and alarm functions, give reliable warnings.
The Final Report of the Investigation was published March 2009.
EDITORS NOTE: Since this incident and the introduction of a fourth runway at Frankfurt, the designations of the runways and taxiways involved and referred to above have changed, but the their layout has not. Runway 07L is now 07C, taxiway G is now taxiway M14 and taxiway H is taxiway L9. It was estimated from the ground radar recording examined during the investigation that at the time the 747 was crossing the runway at what is now M14/L9, the 320 was passing what is now L14.