On 13 October 2009, an Avro RJ100 being operated by Malmö Aviation on a scheduled passenger flight from Stockholm Bromma to Malmö in day Visual Meteorological Conditions (VMC) came into proximity with a unseen light aircraft crossing below which activated a TCAS RA which was followed. The flight crew were unaware that they were outside controlled airspace at the time. No abrupt manoeuvring occurred and none of the 85 occupants were injured.
An Investigation into the incident was carried out by the Swedish AIB. ATC recordings of radar and R/T communications were available.
It was established that the flight crew of the Avro aircraft had reported “field in sight” when under radar control approximately 20 nm north north-east of Malmö in descent through 3600 feet altitude for cleared altitude 3000 feet and, after a request to continue visually, had been authorised by ATC to route to right hand downwind for runway 35 and change to destination TWR frequency. The aircraft had then continued to 2000 feet altitude with the flight crew unaware the base of controlled airspace in the area was an altitude of 2500 feet.
About 12 nm east-northeast of destination and level at 2000 feet, a TCAS RA to ‘Maintain Vertical Speed’ was received and complied with. ATC radar recordings showed that the TCAS target was a VFR light aircraft maintaining approximately 800 feet below the Avro.
STCA was installed at Malmö but an alert was not annunciated by the investigated proximity because it was permanently de-activated in the area involved up to an altitude of 1700 feet. It was also noted that the Short Term Conflict Alert (STCA) system requires that both aircraft which are party to a potential conflict are “within the area for active STCA” before an alert can be generated.
It was noted that during the approved visual positioning at 2000 feet, the aircraft had been in uncontrolled airspace for about a minute with no means for the pilots to determine if the flight was in controlled or uncontrolled airspace because such information was not presented on the proprietary charts which were routinely carried on the aircraft. Only an alert from ATC would have provided such awareness and was not required under prevailing procedures.
The Investigation noted that if ATC authorise a visual approach to be flown by an IFR flight, then ATC remains responsible for separation between that aircraft and others only when the aircraft is in controlled airspace.
It was also noted that although the applicable regulations for an IFR flight arriving at a controlled airport and then given a clearance which might meaning that the aircraft would or could pass temporarily through uncontrolled airspace before later to re-entering controlled airspace prior to landing required that traffic information be provided, it had in this case been “understandable that the controller did not have time to provide traffic information about the unknown aircraft”.
It was determined by the Investigation that the Cause of the incident was that “altitude limitations for visual approach under IFR traffic was not established for flight in the sector in question”.
One Safety Recommendation was made as a result of the Investigation:
- That the Swedish Transportation Agency consider introduction of altitude limitations for visual approach under IFR to Malmö Airport. (RL 2011:01 R1)
The Final Report of the Investigation Report RL 2011:01e was published on 10 January 2011.