SPECIAL INVESTIGATION REPOR

B U R E A U O F A I R S A F E T Y I N V E S T I G A T I O N

BAS! REPORT 896/3051

Boeing 747 VH-EBU&

Boeing 767 ZK-NBE

93km East of Narrandera

29 April 1989

BASIBureau of Air Safety Investigation

Communkations

AIRCRAFT TYPEREGISTRATIONNOMINATED/APPARENT

CLASS OF OPERATIONDEGREE OF DAMAGE TO AIRCRAFTLOCATION OF INCIDENTDATETIME (local)DEPARTURE POINT

DEPARTURE TIME (local)DESTINATION

PILOT IN COMMAND

OTHER PERSONS INVOLVED

Boeing 747 / Boeing 767VH-EBU / ZK-NBE

International Regukr Public TransportNil93 km East ofNarrandera NSW29 April 19890500VH-EBU SingaporeZK-NBE PerthN/AVH-EBU MelbourneZK-NBE AucklandVH-EBU Australian Airline Transport Pilot Licence holderZK-NBE New Zealand Airline Transport Pilot Licence holderAir Traffic Services Personnel

CircumstancesA Boeing 747 (B747), operating a scheduled regular

pubb'c transport flight from Singapore to Melbourne,and a Boeing 767 (B767), operating a scheduled regularpublic transport flight from Perth to Auckland wereinvolved in an alleged close proximity incident nearNarrandera NSW.

Due to staff shortages in the Melbourne AreaApproach Control Centre (AACC), the MelbourneSector 4 airspace was declared to be deactivated by theissue of a Notice To Airmen (NOTAM) 1523. Whilstthis airspace was deactivated, transiting aircraft wererequired to comply with Traffic Information BroadcastArea OTBA) procedures, specified by NOTAM 1522.The B767 flight path would transit this airspace duringthe period of deactivation.

The B747 was offered route shortening at a non-standard level of Flight Level 37 000 feet (FL370) withinSydney controlled airspace under the jurisdiction of theSydney Area Approach Control Centre Sector 6. Thenon-standard level was assigned due to otheri n t e r n a t i o n a ltraffic inbound toSydney operatingbelow the B747.No posi t ivei n f o rma t i o nupdate had beenprovided to theSector 6 controllerabout the progressoftheB767. Flightpaths of botha i r c ra f t werewi th in radarsurveillance rangeand jurisdiction ofthe Sydney Sector6 controller forsome time prior to

the incident. The shortened route would place the B747on a track which would cross that of the B767 at thesame level and approximate time near Narranderaunless some separation action was taken.

The B767 subsequently entered Sydney Sector 6airspace three minutes earlier than flight plannedestimates indicated. As soon as that aircraft contactedSector 6, it was instructed to descend from FL370 to non-standard level FL350 to provide vertical separation withthe crossing B747. The aircraft queried the instructionwhich was verified by Sector 6. However,communications with the B767 were then lost and noreadback of the assigned level was received.

Because of this, the Sector 6 controller then instructedthe B747 to change heading intended to maintainseparation and to eventually pass behind the B767.

ZK-NBE (B767)The B767 flight plan was submitted at Perth at 1438

Coordinated Universal Time (UTC) for a flight from

01

3COCOuu

ZCZC MCC641 280856GG ASSSZRZX I280856!AMMMZIZXCORRECTION :280847 AMMMZIZX1523 .ROTAMN

STOP

A) MELBOURNE F£R 1523 8) 04281400 C) 04282000 E) MELBOURNE CTADEACTIVATION:1

DUE STAFF SBORTAGE, MELBOURNE CTA TO THE NORTH AND WEST OF MELBOURNE(AS DERAILED BELOW) DEACTIVATED.

ATC :FREQ ::V::. 125.7MHZ127.4MHZ130.5MH2131.0KHZ

.; 338.2MHZ.: J»pT AVBL.:NOTE: ̂ DEACTIVATED AIRSPACE !IN THE MELBOURNE FIR: :A) CTA A OUTSIDE ;30NM ML ABOVE A045, WEST OF A:.LIKE ML VOR- DLQ NDB ANDINCLUDING TBE LLFL 120 :GTA :A STEP EAST OF THAT .LIKE, ANDB) -TCTA OUTSIDE: 100NM ML WIT BIN :::THE AREA BOUNDED. "BY A :.LINE COMMENCINGDDE DEGREES .TO :TBE.SW :CORNER OF^T.HE^SY:FIR, THEN;VIA THE 142E MERIDIANTO THE FL200/FL250 TCTA STEP,'CONTINUING"TO A POINT 30NM NORTH OF.GTH,NAR, THEN TO A POINT WHERE '. THE CTA A BOUNDARY EXTENDS TO THE NAR-WG

TRACK, THEN VIA SHE CTA: A BOUNDARY ttp.100NM ML.

B/896/3051

128.2 MHz or 1185 MHz when beyond 150 nauticalmiles Sydney. Whereas the latter frequency was thecorrect frequency to be used in the Southern portion ofSector 6 airspace. The 118.5 MHz VHP facility site islocated at Mt Canobolas, near Orange, almost on thedirect track and only 130 nautical miles fromNarrandera. The B767 crew had made all the requiredbroadcasts on the TIBA frequency 128.95 MHz whilstwithin deactivated airspace. They first became awarethat the event had been reported as an incident whenthey heard it from the media after arrival at Auckland.Investigation of the incident indicated the following:• the Sector 6 controller had no co-ordination update

provided for the Narrandera waypoint• the flight progress strip ETA Narrandera was

correctly based on ATD• the Sector 6 controller was unable to descend the

B747 due to other crossing traffic• an SSR return was observed in the vicinity of

Narrandera indicating FL370, which was believedtobetheB767

• the Sector 6 controller could not determine thefrequency used by the B767 on first contactbecause of the placement and operation of the VHP

control and presentation facilities on controllerworkstations

• the B767 did not respond to the level changeinstruction and the level readout display was slowto indicate a descent had been initiated

• the Sector 6 controller was not permitted to use theMode C level readout for separation purposes

• the Sector 6 controller discussed the situation withmore senior controllers and elected to turn theB747 right of track to avoid crossing the flight pathoftheB767

• radar separation standards were maintained at alltimes

• the aircraft had vertical separation of 2000 feet atthe time of passing

• the B767 had not called 15 minutes prior toentering Sydney airspace for clearance inaccordance with TIBA NOT AM proceduresThe investigation concluded that there was no

breakdown of the prescribed separation standards, andthat although both aircraft had not been formallyidentified on radar there was sufficent information forthe Sydney Sector 6 controller to anticipate that theaircraft painting over Narrandera at FL370was the B767.The off-airway route shortening of the B747, initiatedby air traffic control, added complexity to the prevailingtraffic, airspace management and co-ordinationrequirements.

The investigation noted that at the time that the B767first made contact with Sydney Sector 6 on 128.2 MHz,the VHP transmission was very broken. This can beindicative of an aircraft either with transmitter problemsor on the extreme range of VHP communications. Onthe first communication, Sector 6 instructed the B767to descend to non-standard level FL350. This wasintended to maintain vertical separation between theB767 and the crossing B747. The VHP reception ofSector 6 by the B767 was also most probably broken for

the same reason (ie,ZCZC «CC657 280910GG ASSSZR2X280848 AMMMZIZX1522 NOTAMNA) MELBOURNE :FIR 1522 : (ATS) :04280810 B> 04281400 CJ; 04282000 E> ACFT OPR:INTEMPO! DEACT,; AIRSPACE ARE:TO ADOPT TRAFFIC,INFO -BROADCAST BY ACFT•AND RELATEDPROCEDURES:::(TIBA) AS SPECIFIED Itf ICOA ANNEX 11 ATTACHMENT B. PROCEDURES : AREAS FLW:

: l.A LISTENING WATCH SHOULD BE MAINTAINED ON THE TIBA FREQ 10 MIN PRIOR TOENTERING DEACT AIRSPACE UNTIL LEAVING THE AIRSPACE.

i.2.TIBA FREQ i28. 95MH2::&BV :FL200,'..126.35. FL20Q :AND :BLW.

; 3.BROADCASTS:SHOULD BE\MADE;(A) 10 :MXN PRIOR TO:ENTERING.THE DBACT AIRSPACEIB) 10 MIN PRIOR TO CROSSING A REPORTING POINT(C) 10 MTN PRIOR TO;CROSSING OR JOINING AN ATS ROUTE(D) Af 20 MIN INTERVALS BTN :DISTANT REPORTING POINTS{£) 2̂ 5 MIN BEFORE?::A;-CHANGE. iltTFLT LEVEL(F) AT :THE TIME OF^A'CHANGE TN FLi: LEVEL AND ;

«3> ;AT .ANY TIME CONSIDERED NECESSARY- BY THE PILOT.. 4.FORM OF BROADCAST IS'. TO; 3B STANDARD POSITION REPORT TO ALL STATIONS,

EXCEPT FOR CHANGES:OF LEVEL.: 5.ACFT SHOULD OPERATE/iAT :STANDARD CRUISING LEVELS EXCEPT TO AVOID TRAFFIC

CONFLICTS OR WEATHER ;AVOIDANCE..6.IN:ADDITION TO THE:ABV, IN DEACT OCA: (I) POSITION REPORTS SHALL BE

MADE ON HF (II) COMMUNICATION AND. SAR ALERTING ONLY WILL BE PROVIDED BYFLIGHT .SERVICE

7.POSITION REPORTS SHOULD ALSO BErMADE ON THE ;NEXT APPROPRIATE ATC OR FISAREA FREQUENCY TO OBTAIN; CLEARANCES TO RE-ESTABLISH SASWATCH, 15 MIN PRIORTO LEAVING DEACTIVATED AIRSPACE -FOR CTA/FIA. ;3

8.ALL ACFT MUST VACATE :DEACT i AIRSPACE PRIOR TO. IT'.'. BEING REACTIVATED SO .THATAPPROPRIATE ATC CLEARANCES:: :MAY: :BBv:O8TAXNED.

e q u i p m e n tproblems or out orrange) and theB767 a ircrewqueried thatinstruction. SydneySector 6 verifiedthe instruction andadded that thea i r c r a f t wasrequired to reportreaching FL350.There was noresponse to thisinstruction orreadback of thenew assigned levelby the B767. Thiswas most probablybecause it was thenout of range of theMt Oxley VHPfacility, even atFL370.

B/896/3051

•*.-'

Perth to Auckland via waypoints overhead Adelaideand Sydney. The flight would transit deactivatedairspace promulgated in Melbourne NOTAM 1523 at0848UTC This airspace was normally under thejurisdiction of Melbourne AACC Sector 4. The B767would then enter airspace under the jurisdiction ofSydney AACC Sector 6 at Narrandera.

The flight plan Estimated Time of Departure (ETD)was 1530UTC with the associated Estimated TimeIntervals (ETI) and Estimated Times of Arrival (ETA)providing en-route timings for the following codedwaypoints:

ETI to MALIM 02.51 -ETA 18.21 UTCNYA 02.58 - 18.28ASSS 03.05 - 18.35NAR 03.17 - 18.47RUG 03.31 - 19.01

Once the departure message was received fromPerth notifying the actual departure time as 1542UTC(12 minutes later than flight planned), the aboveestimates could then have been updated as follows:

ETI to MALIM 02.51 -ETA 18.33 UTCNYA 02.58 - 18.40ASSS 03.05 - 18.47NAR 03.17 - 18.59RUG 03.31 - 19.13

This could have given Sydney Sector 6 someexpectation that the B767 would enter the deactivatedairspace at 1828UTC (prior to MALIM waypoint) andexit deactivated airspace at NAR at 1859UTC.

Because of the deactivation of Melbourne airspacethe normal step-by-step co-ordination exchangesbetween the Adelaide, Melbourne and Sydneycontrollers were not completed and the Narrandera stripand estimate could therefore not be accurately updatedby the Sector 6 controller.

The last actual reported position of the B767 was toAdelaide control at 1748UTC when the aircraft reportedover waypoint T6B at 1747UTC, FL370, estimatingMALIM waypoint at 1830UTC; ie. three minutes earlierthan could have been expected by the Sydney Sector 6controller.

VH-EBU (B747)The B747 flight plan was submitted in Singapore at

1132UTC for a flight from Singapore to Melbourne viawaypoints overhead Derby, Parkes, Bindook (nearKatoomba), Shellys (near Goulburn) and Eildon Weir.

B/896/3051

This circuitous route was planned to keep the aircraftwithin controlled airspace, and dear of the Melbournedeactivated airspace which had been notified at0856UTC (Melbourne NOTAM 1523). The aircraft hadplanned to descend from FL370 to the standard levelof FL350 after passing Bindook and tracking towardsShellys and onwards to Melbourne.

The aircraft departed within a few minutes of thenotified ETD of 1215UTC and proceeded as planned.Subsequently, at 1808UTC Adelaide control instructedthe B747 to contact Sydney control on Very HighFrequency (VHP) 128.2 Megahertz (MHz) at the nextwaypoint, T34A. (At 1812UTC, Adelaide controlinstructed another international aircraft also to contactSydney control on 128.2 MHz as primary frequency, butoffered 118.5 MHz as a secondary (alterantive)frequency).

The B747 contacted Sydney control on 128.2 MHzat 1813UTC and reported passing waypoint T34A,maintaining FL370 and estimating Parkes at 1849UTC.At 1836UTC Sydney control Sector 6 advised Melbournecontrol Sector 2 of the B747 inbound via Parkes andrequested if a shorter track from Parkes to Wagga andMelbourne would be available in the Melbourneairspace. Melbourne control analysed the situation andconcurred that the B747 could be given amendedclearance to track Parkes, Wagga, Albury, Eildon Weir,Kinglake and Epping. At 1838UTC, Sydney Sector 6passed this amended clearance to the B747. Then theB747 was given a frequency change from 128.2 MHz to118.5 MHz to maintain continuous communications forthe amended route.

Investigation SummaryInvestigations indicated that the crew of the B767

were given the Melbourne NOTAMs 1522 and 1523 onthe flight deck just prior to departure from Perth. Theydid not consider that there had been a breakdown ofseparation resulting from the incident. The B767 crewconsidered that the incident had been resolved as aSydney control supervisor had spent some timediscussing the matter on air with them. Theyacknowledged that they had the appropriate NOTAMsbut had not fully understood the significance of Para.7of NOTAM 1522.

The B767 crew believed that their clearance fromPerth via planned route was valid through all Australianairspace and that the wording of Para 7 "SHOULD"was not a mandatory requirement even though they hadbeen advised of the frequency by Adelaide as 128.2MHz. It should be noted that the VHP site for the 128.2MHz facility is at Mt Oxley, approximately 260 nauticalmiles north of Narrandera, near Bourke. As VHPcommunications are restricted to line of sightpropagation characteristics, the use of this frequencyplaced the B767 at the limit for communications overthis distance at FL370, and out of communications atFL350.

The crew of the B767 were using Jeppesen chartswhich, similar to the Australian documentation, carriedambiguous frequency data indicating that the choice offrequencies to be used in the Trans Continental ControlArea (TCTA) and Western Routes (from Sydney) were

Loss of communications with the B767 left theSydney Sector 6 controller with minimal options tomaintain separation between the B747 and the B767.The chosen action was to vector the B747 away from theflight path of the B767. Sydney Sector 6 contacted theB747 thirty seconds later and instructed that aircraft toturn right onto a magnetic compass heading of 270degrees for separation purposes. Sector 6 continued tocall the B767. When no contact could be established,the B747 was given traffic information with the relativebearing (2 o'clock) and distance (30nm) from the B767,with the advice that the aircraft was out ofcommunications at that time. The B747 reportedsighting the B767 traffic.

Subsequently, at the time of passing, (190030UTCby radar plot), the aircraft were separated by 10.5nmhorizontally, travelling in opposite directions andachieving 2000ft vertical separation. Sydney Sector 6continued to call the B767 until communications wereestablished on 1185 MHz at 1901.40UTC, some 4minutes 20 seconds after contact was lost at185720UTC The B767 men reported maintainingFL350. At that time the aircraft was 2000 feet below and17 nm from the B747 and increasing the horizontalseparation.

The investigation also revealed that the crew of theB767 and the Air Traffic Service staff did not fullyunderstand the intentions and procedures expressed inthe appropriate Melbourne NOTAMs. This is not areflection of the comprehension skills of the personnel,but an indictment of the complexity and ambiguity ofthe NOTAMs and the procedures.

Significant factorsThe following factors were considered relevant to thedevelopment of the incident1. Adelaide control provided frequency change

instructions to the B767 which provided only onefrequency to call Sydney control Sector 6.(128.2MHz) without nominating a secondaryfrequency of 118 5 MHz, as had been done with otheraircraft

2. Adelaide control co-ordinated the B767's T6B positionreport and estimate MAUM with Melbourne Sector4, which was supposedly unmanned.

3. Because Melbourne Sector 4 airspace wasdeactivated, the B767 estimate MALIM was not co-ordinated with Sydney Sector 6, even though theinformation was accepted and acknowledged by anunknown person in Melbourne.

4. Sydney Sector 6 had lost VHP contact with the B767because it was on the extreme limit of range from thesite through which communications were attempted.

5. There were no VHP coverage diagrams available toair traffic control positions to indicate the coveragelimitations from specific sites.

6. The Sydney Sector 6 controller apparently did notrecognise the characteristics of the broken VHPtransmission from the B767 as typical for atransmission originating from an aircraft at maximumrange.

7. The ergonomic placement of the VHP frequencycall indicator lights on the Sector 6 workstation madeit extremely difficult for the operator to determine thefrequency on which an aircraft was actually calling

SECTORS 1900

MELBOURNESECTOR 4

SHELLYS,**

NARRANDERA

WAGGA WAGGA

B747Right planned route — ..-••Actual route as cleared — ̂ ——Final flight path _._._

B767Flight planned route andActual route flown —— —Deactivated airspaceML Sector4VNFcorarag*MtOxleyMtCanobolas

B / 896 /3051

as all call indicators operated simultaneously whenthe retransmission was active.

8. There were no procedures for air traffic controllersto indicate on the flight progress strips the frequencybeing used to communicate with an aircraft.

9. The off-airways routing of the B747 placed thataircraft across the flight paths of other traffic. Thisadded to the complexity of the airspace managementand the total reliance on continuous communicationswith all aircraft.

RecommendationsIt is requested that the Civil Aviation Authority

give consideration to the following recommendationsto ensure that air traffic control personnel:1. Use consistent phraseology when initiating frequency

change instructions.2. Issue the correct frequency change instruction for the

area in which an aircraft is, or will be, operating.3. Are reminded of the necessity to accomplish

frequency changes before an aircraft is out of VHPrange from the previous VHP outlet.

4. Are provided with documentary evidence of the VHPcoverages available from the outlets under theircontrol.

5. Are provided with training in VHP communicationscharacteristics of the CAA radio telephony systems.

6. Have the control and presentation of the VHF/UHFfrequency call lights modified so that controllers canimmediately determine the frequency on which anaircraft is calling.

7. Have procedures prescribed to indicate thefrequency, coded if necessary, on which an aircraftis communicating, and all subsequent frequenciesrecorded on the flight progress strip applicable to aparticular controller where more than one frequencyis terminated at that workstation.

8. Be advised of this incident as an example of wherethe offering of track shortening and non-standardlevels can result not only in increasedcommunications, control workloads and co-ordination, but may suddenly and unexpectedlyresult in reduced safety standards.

CAA ResponseIn response to this BASI report the Civil Aviation

Authority (CAA) has amended certain instructionspertaining to "Charts", "National ATS ContingencyPlan Guidelines", "Frequency Call Light Displays", andATS procedures.

Whilst agreeing, in general, with the findings of thereport, the following comments are made in relation tothe report's eight recommendations:Recommendations 1,2 & 3

The Authority endorses these recommendations andwill reinforce to all ATS staff the need to use standardphraseologies, wherever practicable. A phraseologysuch as "ABC contact me on [frequency]",is, for example used to instruct an aircraft to changefrequency within a sector, as defined by the NationalATC Sectorisation Plan.

All three recommendations describe techniques thatare taught to all Air Traffic Controllers, who are then

B/896/3051 =

required to indicate the correct application of suchtechniques by passing proficiency checks and obtainingthe appropriate sector rating. If the controller then failsto issue a correct frequency change, an error has beenmade and the check control system acts accordingly.

The use of-staff circulars, originated by theAuthority's Airways Operations Group, is also-beingconsidered as a means of providing ATS staff withgeneral information on matters of technique that havebeen identified by such incidents. The intention wouldnot be to identify specific incidents, but rather to list anyitems requiring attention and provide a brief outline onaction being taken in relation to such items.Recommendation 4

A new chart "Planning Chart Australia" will becomeeffective in June 1990 to provide, in part, an indicationof VHP coverage at 20000 feet, pertinent ATC VHPfrequencies, and the ATC sectors to which they apply.This chart will be available for pilot and ATS staff sothat both parties can utilise this information, as required.Recommendation 5

All ATS staff are taught the characteristics of thevarious VHP an HP communications systems. Theintended publication of the new PCA chart will provideadditional reference material in this regard.Recommendation 6

The Authority will implement this recommendation.Recommendation 7

Changes to existing procedures are not considerednecessary. Flight strips are already over burdened withinformation and on any given route the frequencies areknown to all controllers using the route sectionsinvolved. Procedures are laid down when to changean aircraft from one frequency to another and if differentto normal then the controller will write the newfrequency on the strip as a "one off" situation.

The implementation of recommendation six will alsohelp the controller keep track of the actual frequencybeing used when more than one terminate at a particularworkstation.

TIBA procedures have been amended since thisincident and the National ATS Contingency Plan nowincludes specific instruction on communications failuresituations. Furthermore, AOI/COM 9-1 is beingamended to specifically assign responsibility fornotifying the next ATS frequency in use when TIBAprocedures have been implemented.Recommendation 8

The availability of track shortening and non-standardlevels have been severely limited by the introductionof new instructions to ATC staff.

AOI/RAC 2-25 has been amended to prohibit the useof non-standard levels outside radar coverage, exceptwhere operationally required for safety reasons, on oneway routes or, as approved by the shift supervisor.

In conclusion, the Authority thanks BASI for thereport and its recommendations which, as indicatedabove, have been instrumental in constructiveimprovements being made to existing ATS procuduresand practices.