On 12 June 2010, a requested 22R runway inspection at Helsinki in normal daylight visibility carried out after a severe engine failure during the take off roll had led an Avro RJ85 being operated by Finnish Airline Blue1 on a scheduled passenger flight to Copenhagen to reject that take off at high speed. This inspection had not detected significant debris deposited on the runway during the sudden and severe engine failure. Two passenger aircraft, one being operated by Finnair to Dubrovnik, Croatia and the other being operated by Swedish airline TUIfly Nordic to Rhodes, Greece then departed the same runway before a re-inspection disclosed the debris and it was removed. Neither of the aircraft which used the runway prior to debris removal were subsequently found to have suffered any damage but both were advised of the situation en route.
An Investigation into the consequences of the failure to detect and remove the debris before further use of the runway was permitted was carried out by the Finnish AIB.
It was noted that the symptoms of an engine failure had not been apparent until after 80 knots and that the rejected take off had been commenced at a speed of 100 knots - below the applicable V1 - and had been completed uneventfully. No definite cause of the engine failure was isolated and the main focus of the Investigation was on the runway inspection process at Helsinki.
It was found that the initial inspection had been carried out at the request of ATC acting after a corresponding recommendation by the commander of the RJ85 when his aircraft was taxiing clear of the runway. This inspection was then made over a period of approximately 3 minutes by a single member of the airport maintenance department who reported that the runway was clear. The Investigation found that the ATC request for the inspection had been made strictly in accordance with prevailing procedures which did not require the controller to specify the area to be inspected or give any guidance on what might be found. Neither of the two aircraft which then departed had advised sighting any debris or suffering any potentially related effects but the pilot in command of the RJ85, having ascertained after shutdown the extent of the engine damage, had then contacted ATC to advise of the high probability of runway debris.
The second inspection was carried out by the same vehicle as the first but the airport maintenance shift supervisor joined in the inspection on his own initiative in another vehicle. This time, some 50 pieces of the damaged engine in the range 2-40 mm were found on the left hand side of the runway over a distance of about 400 metres. Some pieces were found to have been “burnt into the runway surface, but could be removed by hand”. Since the recovered pieces were all very small and of the same colour as the pavement, it was noted they could have most easily been detected by an inspection on foot.
It was concluded that:
“(The first) inspection had failed partly because no detailed assessment about the nature and location of the incident was provided with the inspection request and so the airport maintenance unit did not see any specific reason to inspect the runway ‘more thoroughly than usual’. Nevertheless, it was found that ATC actions when requesting the airport maintenance unit to perform an ad hoc runway inspection and providing them with related information were in accordance with extant instructions and ‘established practices’.”
Recovered engine debris shown against the dark-coloured runway surface [reproduced from the Official Report]
Subsequent Safety Action taken by the Airport Maintenance Unit with the aim of improving the effectiveness of runway inspections was noted by the Investigation and.
Three Safety Recommendations were made as a result of the Investigation:
- that the Finnish airport operator Finavia Corporation to make the instructions for runway inspections more specific, so that the inspecting staff would have all available necessary information about the situation at their disposal during the inspection.
- that the Aviation Sector of the Finnish Transport Safety Agency (Trafi) to examine the current status of instructions and oversee that any deficiencies are rectified.
- that Finavia Corporation (should) find out whether foreign object detection technology suitable for the local conditions is available and, based on studies, decide on the necessity of obtaining such equipment.
The Investigation also considered that:
“since the effectiveness of co-operation between ATC and (the) airport maintenance unit largely depends on communication practices and the investigation has revealed that, at least at Helsinki-Vantaa Airport, regular exchange of information is mainly focused on supervisor and senior staff level” it would be appropriate for the airport operator Finavia Corporation to “increase regular and continuous co-operation between ATC and airport maintenance operations staff at all of its airports”.
The Investigation was completed on 16 June 2011 and the Final Report: Investigation report C5/2010L subsequently released