On 24 February 2004, a Cessna 550 on an ad hoc commercial air transport flight to from Rome Ciampino to Cagliari in night Visual Meteorological Conditions (VMC) with line training apparently in progress requested and was approved for a visual approach to the destination runway in use. Shortly afterwards, contact was lost and it was subsequently found that the aircraft had been destroyed by a high speed impact with terrain during descent in ‘dark night’ conditions and the resulting post crash fire with all six occupants killed.
The accident was investigated by the ANSV. It was established that the aircraft had not been fitted with a Cockpit Voice Recorder (CVR), Flight Data Recorder (FDR) or GPWS/TAWS and that, because of the low weight of the aircraft, there was no regulatory requirement for any of these items to be fitted.
The aircraft had been chartered at short notice for a medical mission from its base in Milan Linate. This required positioning to the location of a potential recipient of a heart transplant to collect the medical team involved and take them to Rome where a heart suitable for transplant had become available so as to obtain it and return with it to their base to carry out the operation. This had initially involved a positioning flight to Catania where a patient in need of such a transplant had been identified, but shortly after take off from Linate just after 2200 local time, the destination had been changed to Cagliari where an alternative recipient had been designated.
The operating crew had consisted of two Austrian pilots, the aircraft commander being the Director of Flight Operations and Chief of Training for the Operator. He was found to have had significant experience on the Cessna 500 and similar aircraft, which were the most complex aircraft he had flown, The First Officer also had experience on the Cessna 500 and similar aircraft in proportion to his age. A third low experience pilot of Italian nationality and apparent management responsibilities in respect of both the aircraft operator and the (Italian) aircraft owner was also on board but the Investigation was unable to positively establish his operating status, if any. All three pilots had travelled from Austria to Milan during the afternoon of the same day of the departure from Linate in order to be available to position from there the following day to Olbia, Sardinia and undertake a planned air taxi flight from Olbia to Tirana, Albania. The change to the overnight charter which had subsequently occurred was not known to the crew until after their arrival in Milan.
Following the uneventful completion of the initial flight from Milan to Cagliari, where the aircraft was provided with radar vectors to the Instrument Landing System (ILS) for runway 32 and landed at two minutes past midnight local time, the three-person medical team was boarded and taken to Rome Ciampino.
Evidence available to the Investigation indicated that the return (accident) flight to Cagliari was flown with the aircraft commander in the right hand pilot seat with the First Officer in the left hand pilot seat in order to undergo line training necessary to complete promotion to Captain. As with the previous flights, it was flown on an Instrument Flight Rules (IFR) Flight Plan.
On transfer to Cagliari APP descending in accordance with clearance to FL090, the crew were informed that runway 32 was in use and the weather was passed. APP then advised that an ILS PAPA approach should be expected. It can be seen from the copy of the Jeppesen Chart below (as used by the crew) that this requires routing via the CAR VHF Omnidirectional Radio Range (VOR) before flying an intercept to the ILS LOC. This avoids mountainous terrain to the east of there aerodrome which results in an MSA of 5700 feet.
The Jeppesen IAC as available to the crew without contouring but with spot heights including that of the summit near the accident site (reproduced from the Official Report)
Shortly afterwards, having just left FL100 with a re-clearance to descend to 5000 feet en route to the CAR VOR over the sea, the aircraft commander reported “field in sight” to APP and requested a visual approach. After specifically verifying that the aircraft would maintain its own separation from obstacles, this request was approved and the aircraft set course towards a 4nm final for runway 32. The cloud and visibility conditions recorded at the time of approval of the visual approach were compatible with the request. However, since there had at this point been no recent radar return of the position of the aircraft visible on the APP radar display, this position was verified by contacting Rome ACC who advised that on their radar, the aircraft showing FL 072 at about 22nm from Cagliari. APP then instructed the aircraft to change to the Cagliari TWR frequency with the proviso that descent should not continue below 2500 feet Altimeter Pressure Settings until approved by TWR.
The aircraft checked in with TWR and was instructed to call on short final. In acknowledging this instruction, the aircraft commander reported their position as 23nm from the Cagliari passing an altitude of 4800 feet. Collision with terrain on track in the Sette Fratelli mountains occurred close to the 3333 feet high summit of Mount Bacumalu in “dark night” VMC just over a minute later. The aircraft was destroyed by the impact and a fuel-fed fire which followed and all six occupants were killed.
The topographical Chart as reproduced in the Official Report showing the IFR track to the CAR VOR via waypoint LEDRO in blue and the actual track direct track taken to the site of impact (highlighted with a black arrow) - reproduced from the Official Report
Whilst the Investigation was in progress, the parallel Judicial Inquiry decided to organise a flight in an aircraft of the same type as that involved in similar flight conditions in order to determine the in flight visibility in relation to the claim by the aircraft commander to have visually acquired the airport at the point he did and to determine any relevant limitations to the radar cover feeding the displays at Cagliari APP. An ANSV Observer travelled on this flight and found that:
- visual acquisition of the airport was not possible as had been claimed by the crew of the accident aircraft when requesting and receiving approval for a visual approach.
- the lack of any ground lights in the area of the Sette Fratelli mountains would have precluded the possibility of achieving effective visual separation from the terrain because as a result the area would have appeared as a uniform “flat black colour”.
- The Cagliari APP radar display would not have provided continuity of radar returns from the aircraft.
The Investigation found no evidence of any relevant unserviceability in respect of the aircraft or of ground equipment. It was noted that the approach control service for the Cagliari CTR was provided by the Italian Air Force from the military airbase at Decimomannu, located 8.5 nm north west of Cagliari airport and equipped with both Primary and Secondary radar feeds, the former with a 4 second refresh rate. The ground position of this radar was known to controllers to limit the reliability of returns towards the east - the area in which the accident aircraft made its visual descent. It was confirmed that the transfer of the aircraft from APP to TWR took place when the aircraft was approximately 25 nm from the field.
It was found that, despite the fact that the Air Force “Certificate of Approval” for the APP radar service provided by Cagliari from the Decimomannu airbase on 21 June 2002 had recorded no problems or limitations with the service, subsequent to the accident on 20 May 2004, the Air Force had issued a Notice To Airmen to the effect that east of Cagliari, the coverage of the primary and secondary radar was not reliable below FL110. The content of this NOTAM was subsequently incorporated in the AIPs.
It was considered that “the crew was not particularly familiar with the area around the destination airport” and concluded that the short notice of the requirement to undertake the flights concerned when a duty the following day had been expected would have meant that, despite the applicable flight time provisions being met, “the crew (would not have had) an adequate period of rest…..before starting flight activity at night”.
It was noted that prevailing International Civil Aviation Organisation (ICAO) provisions for the provision of Air Traffic Services were unambiguous in making the safety of aircraft from impact with terrain or obstacles the complete responsibility of the aircraft commander unless radar control service was being provided.
It was noted that an ENAC provision numbered 41/8879/AM.O referenced in AIP Italy and dated 20 June 1991 had removed a previous complete ban on night visual approaches from flights operating for the purpose of commercial air transport or aerial work which had been introduced on 17 April 1991 subject to various conditions contained in another ENAC provision numbered 41/8879/AM.O and issued on the same date. It was noted that these conditions, available only in the Italian language, went beyond the corresponding requirements of ICAO Doc. 4444 but that only after the accident (on 25 August 2004) had and the responsibility for determining operational requirements for night visual approaches flown in Italian airspace been assigned to the State of the Operator - which in the case of the accident aircraft would have been Austria. It was found that the Operator’s Operations Manual Part ‘C’ (where specific guidance and requirements for operating into special aerodromes are required to be placed) simply referred to general information in the Jeppesen Route Manual also carried on board the aircraft.
It was concluded that the Cause of the accident had been “the conduct of the flight to a significantly lower altitude than the prevailing MSA which was insufficient to maintain separation from terrain during a visual approach at night in the absence of adequate visual references”.
Seven possible Contributory Factors were identified, as follows:
- The absence of TAWS, although noted that this was not a regulatory requirement.
- The mistaken acquisition of visual cues believed by the crew to be the lights of Cagliari aerodrome, noting that “the crew was not particularly familiar with the area” and that there was a possibility that they had been subject to the effects of the optical illusion known as the ‘black hole approach’.
- The possibility that the instruction given by Cagliari approach not to descend below 2500 feet QNH may have been interpreted, despite the crew confirming that they would be able to ensure their clearance from obstacles, as meaning that descent to that altitude would be free of obstacles.
- The crew’s failure to use the available instrument approach procedure despite their destination being an unfamiliar airport in an unknown area flown under conditions of total darkness.
- The crew’s request to deviate from the IFR route may have been due to a desire to speed up their arrival at the destination.
- The crew’s failure to note from the chart carried that high terrain was present, which would have been more likely in the absence of colour contouring of terrain on the chart.
- The prolonged period during which the crew had been awake may have contributed to a reduction in their performance.
A total of eight Safety Recommendations were made as a result of the Investigation. Three were issued on 14 July 2004 as follows:
- that ENAV (the State agency responsible for the provision of civil ATS) avoids reference to documents which are difficult to obtain and only written in Italian and provides for publication in the Italian AIP of the full technical and operational requirements currently prescribed in such documents. [ANSV-21/28/4-1/A/04]
- that in order to avoid the extensive misinterpretation of the text (contained in currently prescribed technical and operational requirements) ENAV revises them giving particular attention to those specified in Section 3 of ENAC (Italian CAA) provision No 41/8880/AM.O so as to indicate explicitly what prevents a procedural instrument approach being performed. [ANSV-22/28/4-2/A/04]
- that ENAC should reconsider, in the light of the (availability of GPWS/TAWS), the minimum equipment which should be required in order to perform a night visual approach. [ANSV-23/28/4-3/A/04]
Five further Recommendations, the first re-iterating Recommendation [ANSV-23/28/4-3/A/04] issued during the Investigation but which had not resulted in a corresponding change to requirements, were issued in the Final Report as follows:
- that ENAC with EASA should reconsider a requirement to mandate TAWS carriage on turbine aircraft up to 5700 kg mass capable of carrying six to nine passengers in order to reduce the risk of CFIT accidents. [ANSV-1/28-04/4/A/09]
- that ENAC should evaluate the possibility of raising the awareness of pilots of the risks of the optical illusion known as the “black hole” effect during initial and recurrent training. [ANSV-2/28-04/5/A/09]
- that ENAC, the Italian Air Force and ENAV should establish a system which ensures regular monitoring and timely provision of information in AIP Italy, especially in relation to regulations and procedures so that there are no discrepancies in relation to current legislation. Such verification should be extended to Flight Operations Manuals. In this context, it is also recommended that such information on regulations and procedures contained in both the AIP and Flight Operations Manuals do not give rise to misunderstandings on applicability which could have a negative impact on flight safety. [ANSV-3/28-04/6/A/09]
- that ENAV and the Italian Air Force should check that the instructions issued by different bodies in respect of the provision of air traffic services, especially if they relate to neighbouring airspace, are always properly coordinated and appropriate. [ANSV-4/28-04/7/A/09]
- that ENAV and the Italian Air Force should evaluate the opportunity to conduct a special audit of all radar systems throughout the country which are used for civil aviation in order to verify the actual coverage and report any limitations by NOTAM and in AIP Italy. [ANSV-5/28-04/8/A/09]
The Final Report of the Investigation was published in the Italian language only. This article was based on an unofficial translation of that Report and as such may contain inadvertent misrepresentations of its content.