ANSP info/procedural error

FACTUAL INFORMATION

The crew of a B737, en route from Perth to Melbourne, requested an arrival on runway 34 after receiving the automatic terminal information service (ATIS) information 'W', which indicated that runway 27 was available for arrivals and runway 34 was available for departures. During the period between the crew receiving the ATIS and requesting runway 34, the aerodrome information changed. The latest ATIS information 'V', which the crew copied, indicated that Melbourne aerodrome was operating on runway 27 for departures and runway 16 for arrivals. The crew was advised that runway 34 was not available, due to the operations on runway 16, and was assigned a standard arrival route (STAR) clearance and runway 16. The crew did not hear the assigned runway because of radio interference and requested confirmation from the sector controller that the runway was 27. The sector controller replied that runway 27 was the assigned runway. The sector controller annotated runway 27 on the flight progress strip for the aircraft. The crews of subsequent aircraft were assigned runway 16 by the sector controller.

The crew of the B737 had not advised the sector controller of the code and receipt of the ATIS, nor had the controller verified that the crew had received the latest ATIS.

When the non-duty runway was assigned, the controller was required to annotate the "ops data" line of the aircraft's label on the radar display with the assigned runway. The "ops data" line for the B737 was not annotated with runway 27. Once the runway and the arrival clearance had been issued by the sector controller, there were no further checks to confirm the aircraft's arrival clearance or assigned runway.

The crew had previously requested track shortening and thought that the sector controller was actioning this request by assigning a runway which required fewer track miles to run to a landing. The crew transferred to approach control and continued to track in accordance with the cleared route. Overhead Essendon aerodrome, the crew continued to track eastwards for a left base to runway 27. The approach controller was expecting the B737 to turn left, to the north, for a left base to runway 16. The approach controller cancelled the standard arrival route and radar vectored the B737 for runway 16. As the B737 approached the centreline of runway 27, the crew requested from the controller the runway to which the aircraft was being radar vectored. The approach controller advised them that the vectors were for runway 16. The aircraft landed on runway 16. There was no breakdown of separation.

ANALYSIS

Initially, the sector controller issued the correct STAR and runway to the crew of the B737. However, when the crew queried the assigned runway, the controller replied with the incorrect runway and then annotated the flight progress strip with the wrongly assigned runway. The reason for the controller assigning the incorrect runway and not amending the "ops data" line of the label could not be determined.

The crew of the B737 did receive the latest ATIS but believed that the sector controller was providing them with their previously requested track shortening by assigning them runway 27. Consequently, they did not query the runway assignment with the Approach controller.

SIGNIFICANT FACTORS

1. The controller did not confirm that the crew of the B737 had received the latest ATIS.

2. The sector controller did not confirm the arrival runway, as indicated in the latest ATIS, when queried by the crew.

3. The sector controller did not amend the "ops data" line of the B737's label on the radar display with the assignment of the non-duty runway.

1. Reversal of the flight levels of the two eastbound aircraft.  That is, giving the actual flight level of the first aircraft as that of the second aircraft.  If this was the case, the aircraft in the B747 crew's 1 o'clock would have been at FL 250 as reported by them.
2. Reversal of the clock code position.  Where the 1 o'clock position was transposed with the 11 o'clock position. This may have been related to the mental inversion of the radar screen image required to be performed by the controller to give relevant information to the crew of the B747.  The view of the radar screen is north facing, whereas the B747 was heading south and separation had already been achieved between it and the aircraft below. The controller had ensured separation with the aircraft above by requiring the B747 to level out at FL 280.  Giving traffic on this aircraft was a safety measure to assist the B747 crew's situational awareness.

There also appeared to be a misunderstanding of the request from the B747 crew as to clearance to the next waypoint. The controller cleared the B747 to TAPOP when the request was direct to TAXON. This misunderstanding was not considered relevant to this occurrence.

The TCAS display reported by the captain of the B747 was due to the type of TCAS on the aircraft. TCAS II with a 604 software update will display a proximity target if the target is currently within 6 NM and 1,200 ft of the TCAS aircraft.  There was no traffic advisory given by TCAS, but the aircraft was displayed on the screen due to this sensitivity.

SIGNIFICANT FACTOR

Incorrect traffic information was passed to the crew of the B747.

The crew of the BA146 requested a clearance from the Alice Springs aerodrome controller (ADC) and were cleared via ANGAS and their planned route at flight level (FL) 200. The BA146 taxied late for departure and the crew requested track shortening via the direct route to reduce the delay to the schedule. At FL200 the BA146 would leave controlled airspace at 120 NM Alice Springs (which is 60 NM from Ayers Rock). This was also the point at which the crew of the BA146 expected to commence descent to Ayers Rock.

The ADC had a flight plan for a B737 flight from Ayers Rock to Alice Springs at FL270 and he was aware of the route procedure. The B737 had earlier departed from Alice Springs, but later than scheduled. The ADC surmised that as the aircraft had departed Alice Springs late, then it would depart Ayers Rock late as well. If this was the case, the ADC assessed the BA146 and the B737 would not conflict on the direct track. Also, there was some uncertainty amongst controllers regarding which aircraft were required to track via ANGAS. The ADC understood that aircraft operating at FL200 and below could be cleared on the direct track if requested by the pilot. He recleared the crew of the BA146 to track direct to Ayers Rock at FL200.

Shortly after the BA146 departed Alice Springs the B737 taxied at Ayers Rock and requested a clearance from sector control. The clearance request for the B737 was relayed via flight service in accordance with air traffic service (ATS) procedures. Ayers Rock aerodrome is located outside controlled airspace (OCTA) and the sector responsible for the area does not have radio facilities which would enable direct speech with aircraft on the ground. The B737 crew was instructed to track from Ayers Rock to Alice Springs and to maintain FL190 due to the BA146 at FL200. The crew of the B737 was provided with traffic information on the BA146 plus other pertinent aircraft. After departing, the crew of the B737 reported to flight service that the aircraft was maintaining FL190.

Following discussion between the ADC and the sector controller, it was agreed that the B737 would be transferred to the ADC, from flight service, to obtain a clearance into controlled airspace (CTA). The sector controller concurred with the ADC's intention to clear the B737 into CTA on climb to FL270 after separating the aircraft from the BA146. The crew of the BA146 reported at 120 NM Alice Springs. At this point the BA146 was leaving CTA for OCTA, and the ADC was no longer required to provide separation from other aircraft. The ADC issued traffic information on the B737 including the departure time from Ayers Rock and that it was tracking in the opposite direction on climb to FL270. He then instructed the crew to contact flight service. The ADC did not advise the crew of the BA146 that the B737 had been instructed to expect a clearance at FL190 or that aircraft's estimate for Alice Springs.

The crew of the BA146 changed to the flight service frequency and reported their position as 56 NM east of Ayers Rock, left FL200 and estimating the aerodrome at 0344 UTC. Prior to leaving CTA the crew of an IFR category aircraft is required to report position on the flight service frequency. This is to ensure that other aircraft, which may be flying in close proximity of the boundary between CTA and OCTA, can take action to avoid the aircraft leaving CTA. Alternatively, the change to the flight service frequency enables the crews of any potentially conflicting aircraft to converse and arrange their own separation. Also, the crew of an aircraft which intends to change level OCTA is required to report the intended change to flight service one minute prior to commencing the change of level. Again, this is to ensure that other aircraft which may conflict have time to avoid or to arrange separation from the aircraft changing level. The crew of the BA146 did not complete either of these actions before leaving CTA or descending from FL200.

The BA146 crew advised flight service that they had traffic information on the B737 on climb to FL270. Flight service immediately advised the crew that the B737 was on climb to amended level FL190. The BA146 crew asked whether the B737 had departed Ayers Rock. Flight service advised the departure time of the B737, that the aircraft was maintaining FL190 and that the B737 crew was operating on the flight service frequency. The BA146 crew then transmitted that they had left FL180. The two crews subsequently advised their respective distances from Ayers Rock which indicated they were 10 NM apart and yet to pass each other. The crew of the BA146 had descended their aircraft through the level of the B737 prior to establishing the relative positions of the two aircraft.

There was no breakdown in separation.

ANALYSIS

After falling behind schedule, the crew of the BA146 requested air traffic control approval to track direct to Ayers Rock in an endeavour to make up time. This request was contrary to the preferred routing detailed in ERSA. The crew were aware that the diversion route was implemented to minimise the potential for conflict between aircraft operating between Alice Springs and Ayers Rock. However, they felt that the commercial interests of the airline would be better served in regaining the schedule. They did not give due consideration to the flight safety aspects inherent in their decision.

The ADC was unsure of the correct procedure regarding which flights could operate on the direct track from Alice Springs to Ayers Rock. This was despite the fact that the ERSA stated that the preferred route for aircraft operating between Alice Springs and Ayers Rock was via ANGAS. He assessed that the B737 would not conflict with the BA146, but he had no means to ensure that this remained the situation, especially during the period of each aircraft's flight outside controlled airspace. Use of the diversion route via ANGAS by the BA146 would have ensured that the two aircraft did not conflict outside controlled airspace.

The ADC did not provide accurate traffic information to the crew of the BA146 before the aircraft left CTA. The advice that the B737 was to climb to FL270 may have led the crew of the BA146 to expect that the B737 would be above their level before they left CTA. Also, the ADC did not advise the crew of the BA146 of the B737's estimate for Alice Springs. Provision of this information would have enabled the crew of the BA146 to estimate the time they would pass the B737 which would have assisted them in assessing the potential for conflict OCTA.

The inaccurate traffic information provided by the ADC about the B737 may have lulled the crew of the BA146 into thinking that there was no likelihood of conflict OCTA. Consequently, they may not have been as vigilant in their adherence to procedures as usual. The lack of the report by the BA146 crew, on the flight service frequency, at least one minute prior to commencing descent was a failed defence for the safe conduct of the flight. A second failed defence was the lack of the transmission of a position report on the flight service frequency prior to leaving CTA. Had the crew of the BA146 made either of these reports there was every possibility that the crew of the B737 would have transmitted their position details. This would have alerted the crew of the BA146 to the fact that the two aircraft may conflict once their aircraft descended, and the two crews could have arranged appropriate separation.

SIGNIFICANT FACTORS

1. The crew of the BA146 requested the direct track contrary to the preferred routing instructions in the ERSA.
2. The ADC was not sure of the requirements relating to aircraft tracking to/from Ayers Rock.
3. The ADC did not provide adequate traffic information to the crew of the BA146.
4. The crew of the BA146 did not comply with radio reporting procedures detailed in AIP

SAFETY ACTION

Local safety action

1. Airservices Australia issued a temporary local instruction to air traffic controllers instructing that aircraft operating between Alice Springs and Ayers Rock at altitudes above 10,000 ft, and intending to land at Ayers Rock, are to be cleared via ANGAS unless weather conditions preclude the use of the track.
2. The operator of the BA146 issued two notices to pilots. The first notice clarified the radio procedures to be used by pilots when operating in CTA prior to descending OCTA. The second notice instructed pilots that they must track via ANGAS (unless ATC requires alternative routing) and also reminded them of the requirement to report to flight service prior to leaving CTA.

The pilot of VH-PJM was enroute Forbes to Brewarrina at 6,000 ft initially estimating Nyngan at 0941 EST but later revised the estimate to 0931. The pilot of VH-XMM was enroute Walgett to Hamilton at 6,000 ft initially estimating Tottenham at 0910 but revised the estimate twice, the last being 0921. Based on the original flight plan/ flight progress strip estimates for both aircraft, the time of passing in the Tottenham area would have been 0905 with PJM approximately 45 NM south-south-east of XMM.

The pilots revised their estimates enroute because XMM encountered a headwind component whereas PJM encountered a tailwind component. However, by the time the Flight Service operator had passed traffic information to both pilots, both aircraft had passed within 5 NM of each other at 6,000 ft.

The Flight Service operator advised that at the time of the breakdown in separation his traffic workload was fairly high. He failed to realise that the revised estimates placed both aircraft in the Tottenham area at approximately the same time.

The pilot of VH-NPD, operating IFR and tracking from Port Augusta to Adelaide at 7,000ft, requested Adelaide Flight Service for a change of altitude to 9,000ft. Adelaide Flight Service arranged the altitude change and advised there was no other IFR traffic in the area.

VH-JVN, another IFR aircraft, had been cleared direct from Adelaide to Leigh Creek at 9,000ft, and therefore not assessed by air traffic control as traffic for NPD. The flight route was later changed to via Ardrossan, which put it on a reciprocal heading to NPD. The possibility of a conflict was not recognised by the sector controller before the two pilots had become concerned about the situation and arranged their own separation.

The aircraft passed each other within 1km at the same altitude.

The Melbourne FSO notified Sydney FS that the Metroliner was taxiing at Dubbo and was provided with traffic information on another aircraft. The Metroliner departed Dubbo, and the crew reported their departure to Melbourne FS and broadcast a departure report on the Dubbo mandatory broadcast zone (MBZ) frequency. The Melbourne FSO notified the crew of the Metroliner the traffic information provided by Sydney FS and notified Sydney FS of the departure time of the Metroliner.

As the Metroliner climbed enroute, the crew observed another aircraft approaching overhead Dubbo from the northeast. The crew attempted to contact the pilot of the other aircraft via the MBZ and FS area frequencies. As the Metroliner passed 8,000 ft at approximately 5 NM from Dubbo the crew estimated they went through the level of the other aircraft.

The callsign of the other aircraft was established shortly after when the crew of the Metroliner overheard the pilot of the Mooney report overhead Dubbo at 8,000 ft.  The crew of the Metroliner changed to the Sydney FS frequency and confirmed the other aircraft's callsign and track details with the Sydney FSO.

ANALYSIS

The Melbourne FSO estimated the flight of the two aircraft would not be in conflict based on his experience and understanding of Metroliner aircraft performance. He considered the aircraft to be well separated despite the fact that the flight information on the flight progress strips indicated that the aircraft met the criteria for traffic in conflict detailed in the MATS.

The FSO had recently undergone a performance check and had received favourable comment in relation to his ability in assessing conflicts between aircraft. This may have led the officer to be somewhat over-confident in his abilities and possibly caused him to trust his own instincts in preference to standard procedures.

SIGNIFICANT FACTOR

The Melbourne FSO did not comply with the procedures in the Manual of Air Traffic Services for the provision of traffic information to IFR category aircraft.

FACTUAL INFORMATION

An instrument flight rules (IFR) flight plan had been submitted for a training flight in a Cessna 172 aircraft departing from Kempsey to Port Macquarie and various other points before returning to Kempsey. The flight was a navigation exercise with a student pilot accompanied by an instructor. The flight plan had been received by the relevant flight information centre. The student pilot broadcast a taxi call on very high frequency (VHF) radio while on the ground at Kempsey,, but he did not receive a response from flight service. The taxi call was in accordance with radio transmissions required for IFR flights and the pilot included the term "IFR" in his transmission. The Cessna was not fitted with a high frequency (HF) radio and the pilot continued the flight using the VHF radio. The Cessna became airborne at Kempsey without the pilot nominating an estimated time of departure for search and rescue ("ETD for SAR") with flight service. The first contact with flight service was after becoming airborne at Kempsey. The pilot then reported departure but did not advise the flight service officer that the flight was operating under the IFR category.

The flight plan had been processed in the flight service centre and a strip posted in the suspense bay on the console applicable to the Kempsey region. However, the flight service officer did not notice the flight strip and assumed the Cessna was a visual flight rules (VFR) category flight because the pilot did not notify the flight as IFR when he reported airborne at Kempsey. Consequently, the officer did not provide traffic information or activate the strip which remained in the suspense bay. During the period between the time the pilot of the Cessna 172 reported airborne and the time he reported his departure from Kempsey, the flight service officer handed over duties to a new officer. The new officer acknowledged the departure report and advised the pilot the area QNH. As there was no strip in the active bay, and the fact that the previous officer had not briefed her on the Cessna during the handover, the new officer also assumed the flight was VFR category. The new officer did not observe the flight progress strip for the Cessna in the suspense bay and did not provide traffic information.

At the same time, a DeHavilland Dash 8 aircraft conducting a regular public transport flight (RPT) from Sydney, inbound to Port Macquarie on descent, reported on the flight information area frequency. The crew of the Dash 8 received traffic information on two other IFR flights in the area but not on the Cessna. Nor did the pilot of the Cessna receive traffic information on the Dash 8 or any other IFR aircraft. The crew of the Dash 8, after making an inbound broadcast on the Port Macquarie mandatory broadcast zone (MBZ) frequency, established communications with the Cessna pilot. During the exchange of position information, the crew of the Dash 8 ascertained that the Cessna was IFR category. The Dash 8 crew then queried the flight service officer regarding traffic information on the Cessna and the officer replied that she was unaware of the Cessna. The flight service officer then contacted the pilot of the Cessna on the area frequency, obtained flight details and provided traffic information to, and about, other IFR aircraft. The pilot of the Cessna observed the Dash 8 as that aircraft descended for landing at Port Macquarie. The Cessna did not conflict with the Dash 8 or other IFR- category aircraft. The flight service officer later found the flight strip for the Cessna amongst other strips in the suspense bay.

ANALYSIS

The Aeronautical Information Publication (AIP) OPS NCTL - 3 para. 47.1 states that an "IFR aircraft operating from non-controlled aerodromes must report to ATS before taxiing. If unable to establish contact, proceed in accordance with para. 45.1." Paragraph 45.1 of the AIP indicates that if an aircraft is unable to contact air traffic services on VHF or HF while taxiing, the flight may proceed on a broadcast basis provided:

1. contact is established as soon as possible after take-off, and
2. for non-RPT flights, an estimated time of departure for search and rescue (ETD for SAR) has been established with a maximum of 30 minutes from ETD.

In this incident the pilot of the Cessna was unable to establish communications with flight service but continued the flight on a broadcast basis without establishing an ETD for SAR. The act of nominating an ETD for SAR may possibly have alerted the flight service officer to the fact that the flight was IFR. Also, the incident may not have occurred if the pilot had reported the IFR category of the flight to the flight service officer on first contact, or during the departure report. If the report had been made, the flight service officer would have been alerted that the flight was IFR category and would have provided the appropriate traffic and SAR alerting service. This would have probably been the situation whether the officer observed and used the flight strip or not.

While both flight service officers should have been alerted to the flight by the presence of the flight strip, the lack of IFR category notification in the transmissions from the pilot of the Cessna predisposed both officers to believe the flight was VFR category. Consequently, they did not re-check the suspense bay for a flight strip nor seek confirmation from the pilot. The instructor in the Cessna was aware that the flight service officer had not provided information appropriate for an IFR flight but did not query the officer. Confirmation by the instructor or the pilot of the IFR category of the flight would have ensured that the appropriate service was provided.

Both flight service officers displayed poor work technique on the handover/takeover, which was inadequate. They did not review all the information that was available to them on the console. Had either officer checked the suspense bay on an opportunity basis they may have observed the strip and recognised the flight was IFR category.

The Cessna pilot's adherence to MBZ procedures in broadcasting position information when approaching Port Macquarie was an active defence in the incident and served to break the chain of events. The pilots of the Cessna and the Dash 8 were able to ensure their own immediate separation by providing position reports using the MBZ frequency and to subsequently establish the Cessna's category with flight service. Ultimately, this enabled all IFR aircraft in the area to receive the necessary traffic information and for the Cessna to be provided with a traffic and SAR alerting service.

SIGNIFICANT FACTORS

1. The pilot of the Cessna 172 did not report "IFR" on first contact with flight service.
2. Neither flight service officer adequately scanned the console during the handover/takeover procedure.

SAFETY ACTION

Local safety action

As a result of this incident and other recent minor occurrences, the Manager Flight Service Sydney has:

1. reviewed handover/takeover procedures; and
2. formed a post-incident review committee to vet incidents for deficiencies and to recommend measures to minimise recurrences.

Bureau of Air Safety Investigation safety action

The Bureau of Air Safety Investigation issued interim recommendation IR960096 to Airservices Australia on the 5 November 1996:

"The Bureau of Air Safety Investigation recommends Airservices Australia amend the Aeronautical Information Publication to clarify the requirement for IFR category flights to report "IFR" on first contact with ATS when operating from non-controlled aerodromes."

An Australian registered B767 aircraft arrived at Denpasar (Bali) aerodrome at night, and amid several active thunderstorms. The weather forecast indicated fine weather, but on arrival, Instrument Meteorological Conditions (IMC) prevailed. Inside 10NM from the aerodrome, the crew needed to avoid three thunderstorms which made instrument approaches difficult.

There was no advice to aircrew of the presence and intensity of the thunderstorms on the 'Meteorological Information to Aircraft in Flight' (VOLMET) or the Automatic Terminal Information Service (ATIS). Air traffic control did not provide any updates on such storms.

Navigation was made more difficult as the main aerodrome navigational aids were overdue for calibration and the relevant NOTAM indicated they were to be used 'with caution'. The crew made two missed approaches before successfully landing at the destination. The Bali VOR approach aid had been reported to be up to 12 degrees out of alignment, but air traffic control were able to have a ground technician ensure that it remained within ground tolerances to permit instrument approaches in IMC.

The investigation revealed that the aircraft engaged in performing the flight testing of the Bali navigational aids had been placed unserviceable the day before it was due to commence testing at Bali. The aids were to be rescheduled for testing as a priority, once the aircraft was serviceable.

Safety Action

As a result of the investigation, air traffic controllers were reminded by their local air traffic services management, of their responsibility in providing accurate weather updates to aircrew. Controllers were also reminded of the requirement to provide such weather information on the ATIS and VOLMET services.

On request from Indonesian ATS management, Australian operators were asked to report any discrepancies in the navigational aids to air traffic control by radio at the time of the occurrence, so that ground technicians can investigate the cause immediately.

SEQUENCE OF EVENTS

When the crew of the aircraft listened to the Automatic Terminal Information Service (ATIS) before commencing their descent, there was no advice that an instrument approach could be necessary. After initial contact with Maroochydore Tower, the crew were cleared to descend to 3,000 ft. The controller co-ordinated another IFR aircraft and one VFR aircraft to give the regular public transport jet priority. However, the Aerodrome Controller did not advise the crew to expect an instrument approach but gave them the option of a DME Arrival or an 18 VOR/DME approach via the 10 DME arc. As the aircraft was still at 4,000 ft and close to the aerodrome, the crew accepted the only viable option of an 18 VOR/DME approach.

The aircraft did not become visual at the minimum descent altitude and the crew elected to divert to Brisbane where a 19 ILS approach was flown to a safe landing.

The captain later complained of the lack of operational information, "indecision" by the ADC, and no advice of an amended terminal area forecast (TAF), special forecast (SPECI) or advice from Brisbane Approach that an instrument approach would be required.

ANALYSIS

The captain's complaint about the lack of operational information regarding an "expect instrument approach" message is valid. He misunderstood the ADC's offer of a choice of instrument approaches as indecision.

The Bureau of Meteorology reviewed the forecasting aspects and conceded that the Maroochydore TAF should have continued with INTER which would have alerted the pilot to expect weather difficulties and to plan for it by carrying extra fuel.

The crew cramped their approach by descending to only 4,000 ft when they had been cleared to descend to 3,000 ft. They apparently did not remember the clearance even though the automatic voice recording tape revealed that they had acknowledged the 3,000 ft clearance.

SAFETY ACTION

Airservices Australia's Maroochydore procedures were modified on 17 May 1995 to include an "expect instrument approach" message in the ATIS when appropriate.

The purpose of the flight was to conduct an instrument rating renewal which included an instrument approach to Devonport. As the aircraft broke clear of cloud, the pilots became concerned that the aircraft was considerably lower than expected. Flight instrument indications appeared normal, both during and after the flight. Subsequently, the supervising pilot queried the Melbourne Regional Briefing Office (RBO) regarding the accuracy of the Automatic Terminal Information Service (ATIS) broadcast, on which the instrument approach had been conducted.

The pilot believed that the QNH was in error by approximately 12 hectopascals (hPa), resulting in the aircraft being approximately 360 ft lower than expected, and the wind was from the opposite direction.

Checks by the RBO indicated that the Bureau of Meteorology had not issued a current Devonport aerodrome Meteorological Report (METAR). This was due to the report message generated by the automatic weather station at Devonport being rejected by the Bureau of Meteorology computer.

The relevant air traffic service (ATS) officer had unknowingly broadcast an invalid Devonport METAR stored within ATS computer systems. Internal investigations by ATS revealed that as a result of a software problem, and the absence of a current Devonport METAR, the previous issue (24 hours old) had been retained and broadcast in error. Had a new, valid METAR been received it would have over-written the older, invalid message.

The QNH used for the approach was 1010 hPa in lieu of the actual 996 hPa, placing the aircraft approximately 420 ft lower than expected. The ATS computer system does not provide the origin time of the METAR. This was a fail unsafe deficiency.

The Civil Aviation Authority took immediate actions to prevent a recurrence by implementing revised procedures in the national communications centre.

The following factors contributed to the development of the occurrence:

• The Devonport automatic weather station report was rejected by the Bureau of Meteorology computer.
• ATS officer unknowingly broadcast an invalid METAR.
• ATS computer error.
• ATS computer failure to provide message origin time for metar.
• This resulted in the pilot being provided with an incorrect QNH.