International

Report not released due to no IP comment from the Indonesian agency on this joint investigation report. ASOR hard copy held on occurrence file. Report not to be released without the approval of the Director or a DD Signed Alan L Stray Deputy Director Investigations 6 July 1998

During cruise at FL370 in IMC, all aircraft automatic navigational aids, autopilot, autothrottle, flight directors and the attitude director indicator mode annunciators, failed simultaneously. The crew were unable to regain the flight directors or re-engage an autopilot and the inputs to these systems were unavailable. The flight management computers continued to function, but the waypoints had to be sequenced manually, and the navigation log had to be manually upgraded for time and fuel calculations. There was no wind, time or temperature available, but groundspeed was displayed. Attempts to reinstate the automatic equipment by cycling the circuit breakers was unsuccessful. The aircraft was flown manually to Brisbane without further incident.

Ground investigation at Brisbane determined that both sensors in the total air temperature (TAT) probe had failed. The operator is investigating the failure in conjunction with the manufacturer.

FACTUAL INFORMATION

NITE 01, a United States Navy F-14 aircraft, had departed from the Atsugi Naval Air Facility, Japan on an Instrument Flight Rules (IFR) plan that included an exercise within Restricted Area R116. The restricted airspace R116 was used for military exercises, the northern end of which was approximately 6NM south east of the track of the B767. The F14 pilot cancelled his IFR status during his initial climb, choosing to proceed under Visual Flight Rules (VFR) procedures.

The crew of the B767 were approaching flight level (FL) 250 while descending into Narita, Japan, when they received a Traffic Alert and Collision Avoidance System (TCAS) resolution advisory (RA) instruction to climb. During the transition from descent to climb, they saw a military aircraft passing in the opposite direction at high speed, approximately 500 ft below them.

At approximately the same time, the air traffic controller observed radar returns from a VFR aircraft departing R-116 at FL250 and passed this information to the crew of the B767. He also contacted the pilot of the F-14 to establish that pilot's intentions. The B767 was climbing through FL255 (approximately) when the military aircraft passed.

The rules for VFR flight in Japanese airspace were such that a pilot could choose to conduct a flight using a 500 ft separation standard up to FL290 without an airways clearance, provided a listening radio watch was maintained on air traffic control frequencies. These procedures allowed the pilot of the F-14 to leave R-116 under VFR and maintain his own separation, of at least 500 ft, from the B767. He stated that he had the B767 in sight and was listening on the control frequency. Therefore, he had complied with the 500 ft separation standard for VFR flight below FL290.

The aircraft passed with approximately 500 ft vertical separation and no appreciable horizontal separation.

ANALYSIS

The TCAS advice to the B767 crew was a genuine alert as the respective flight paths were within the envelope for a RA alert. In this case, the crew manoeuvred their aircraft to a comparatively safe altitude, allowing the military pilot to pass beneath their aircraft.

SAFETY ACTION

As a result of the investigation, the Japanese Civil Aviation Bureau has requested the United States Air Force (the body responsible for overall military operations in the area) to remind all pilots under their jurisdiction of the proximity of IFR air routes and of the general civil airspace structure, and also to remind their pilots of the requirement to maintain adequate separation from civil aircraft.

Additionally, the Japanese Bureau has asked for military training to be kept, as much as possible, within the specified training areas.

At Sydney, the aircraft had been released for service, prior to departure for Bangkok, with the number three engine fire detection 'B' loop inoperative, in accordance with the provisions of the minimum equipment list. The remaining 'A' loop would be used for fire detection and warning for the engine. The aircraft operated normally to Bangkok, where a transit service was performed before the next sector to Rome.

The subsequent take-off was rejected at 140 knots when the fire warning for number three engine activated. The aircraft returned to the gate where eleven of the sixteen mainwheels deflated due to overheating. The mainwheels were changed. Rectification of the fire warning problem consisted of repairing a broken wire at the 'B' fire detection loop connector, adjacent to number three engine starter motor. Both 'A' and 'B' loops then tested normally.

As the aircraft was rotated during the next take-off the number three engine fire warning activated again. The crew carried out the fire warning actions and shut down the engine. Fuel was jettisoned to bring the aircraft to maximum landing weight, prior to returning to Bangkok. An inspection of the engine revealed two holes burnt in the combustion case adjacent to the fire detection loops. The holes allowed hot gasses to escape and activate the fire warning system.

Investigation of the incident by the operator has resulted in a change to company procedures. Any rectification for a fire warning defect will now require a ten minute minimum high power ground run to verify the integrity of the engine. In addition, the inspection intervals for combustion cases have also been reduced.

Report not released due to no IP comment from the Indonesian agency on this joint investigation report. ASOR hard copy held on occurrence file. Report not to be released without the approval of the Director or a DD Signed Alan L Stray Deputy Director Investigations 6 July 1998

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.

An Australian-registered B747 was maintaining flight level (FL) 350 on a flight from Sydney to Hong Kong and was approaching the Zamboanga very high frequency omni-directional radio range beacon (VOR). The crew received a traffic alert and collision avoidance system (TCAS) traffic information advice on an unidentified aircraft at the same level, crossing from right to left and also converging on the Zamboanga VOR. The crew of the B747 initiated a right turn that ensured that their aircraft would pass behind the other aircraft. There was a breakdown of separation.

Investigation by the Bureau in conjunction with the Air Transportation Office of the Republic of the Philippines, established that the other aircraft was foreign-registered and that the crew of that aircraft had been instructed by Manila air traffic control to climb to FL 370 for separation with the Australian aircraft. The instruction had been correctly acknowledged by the crew at the second attempt. The instruction included an authorisation to descend back to FL 350 when 5 minutes past the Zamboanga VOR.

Manila air traffic control had taken all necessary action to ensure positive separation of the two aircraft. The reason why the foreign-registered aircraft was not at FL 370 when passing the Zamboanga VOR could not to be determined.

The crossing point of the two air routes at Zamboanga was not under radar surveillance at the time of the occurrence. However, as part of the improvement to the air traffic system by the Government of the Philippines, a new radar head was commissioned late in 1996 and now provides coverage in this area.

Some of the communication problems appeared to be attributable to the similarity of several of the aircraft callsigns. It is probable that the use of HF communications with some aircraft also contributed to the controllers' communication difficulties.

FACTUAL INFORMATION

An Australian registered B747 aircraft had departed Tokyo on a flight to Sydney. The crew had been radar-vectored by air traffic control around an active military restricted area (R116) and were commencing a left turn to intercept their planned route in accordance with the instructions received. As the aircraft climbed through flight level (FL) 220, the crew received a traffic alerting and collision avoidance system (TCAS) traffic advisory warning of unidentified aircraft crossing from right to left and climbing from a level beneath that of the B747.

A pair of U.S. military FA-18 aircraft had departed from the Atsugi Naval Air Facility to operate in R116, which was located just east of the air route which the B747 was intercepting. Initially, the formation was proceeding under instrument flight rules but changed to visual flight rules on passing 9,000 ft, and tracked visually to the exercise area. Their rate of climb at this time was approximately 6,000 ft/min.

After receiving the TCAS traffic advisory, the crew of the B747 saw the military formation and, as the formation had changed course to be in conflict with the predicted track of the B747, they elected to increase the rate of climb and continue the left turn, to ensure separation from the FA-18s. During this manoeuvre, the rate of climb of the B747 reached 5,000 ft/min, higher than normal for this stage of flight. No traffic information was given by air traffic control in relation to the FA-18 aircraft.

While the crew of the B747 were carrying out their evasive action, the crews of the FA-18s had sighted the B747 and commenced a level-off manoeuvre to maintain FL 225. They calculated that their track to R116 would have conflicted with that of the B747, and assessed that as that aircraft had left FL 225, vertical separation would be achieved by the time horizontal separation was lost.

Radar analysis indicates that the aircraft passed with a minimum of 1,200 ft vertical difference while there was no horizontal separation. Because the appropriate standard is a minimum of 1,000 ft, no breakdown of separation occurred.

ANALYSIS

The FA-18 pilots were operating in accordance with the "see and avoid" principle of visual flight. They acted in accordance with the rules for aircraft transiting to or from the restricted area and maintained a level beneath that already vacated by the B747.

The crew of the B747 reacted to the visual sighting of military aircraft closing rapidly on their aircraft and on a track that was in conflict with their intended flight path. The TCAS equipment confirmed that the rate of closure and track change of the FA-18 formation would place the aircraft in imminent conflict. Even though there was no resolution advisory, the B747 crew elected to commence an evasive manoeuvre based on their observations. They had no information on the intent of the military crews and did not know of the decision of those pilots to level off below their aircraft.

The air traffic controllers were aware of the visual flight procedures used by the military formation and only had a requirement to pass traffic information on such flights if their other duties allowed. In this case, the controller was too busy to pass traffic to the Australian crew. This crossing point is a particularly busy section of airspace and it is normal for traffic information not to be given as military crews are required to remain clear of civil aircraft.

SAFETY ACTION

The Japanese Civil Aviation Bureau advised the military authorities to remind pilots of the airspace structure and of their requirement to remain well clear of civil traffic.

The Bureau requested that the operator fully brief crews on airspace requirements and military crossing points, and how TCAS advisories can be expected in this environment.

FACTUAL INFORMATION

Two international B767 aircraft were tracking northbound on air route B220 at Flight Level (FL) 350, the second approximately 20 minutes behind. All separation in regard to these two aircraft was correctly established and maintained. The aircraft were under the control of Brisbane Sector 10 and were due to cross into the Papua New Guinea flight information region (FIR) at VIPAM, the mandatory reporting position at the FIR boundary. The controller had co-ordinated the pilot estimates for VIPAM with Port Moresby Control.

Subsequently, an A310 aircraft taxied at Port Moresby for a flight to Cairns via air route B220 and the crew had been cleared to climb to FL370 by Port Moresby Control. The Sector 10 controller agreed to this flight level as initial separation responsibility was with Port Moresby Control.

The A310 departed at 1316 EST and was estimating VIPAM at 1341 tracking southbound. As the first B767 was estimating VIPAM northbound at 1346, there was insufficient time to allow an unrestricted climb to FL370 for the A310. The crew were therefore instructed by Port Moresby control to maintain FL330.

During the subsequent co-ordination between Port Moresby control and Sector 10, it was agreed that Sector 10 would accept responsibility for providing separation between all three aircraft and initiating a climb for the A310 when available. During this co-ordination the Port Moresby controller offered the use of Port Moresby distance measuring equipment (DME) to assist Sector 10 in this separation function. The Sector 10 controller was unsure of the process for using such equipment in Australian airspace and decided not to use the DME standard.

Having accepted responsibility for separation, the Sector 10 controller correctly calculated, using mental processes only, a time of passing for the A310 and the leading B767. The estimated time of passing was 1343.30 (transmitted to the aircrews as 1343) and the aircraft sighted each other at that time. However, further climb for the A310 was still dependent on separation being provided with the second B767, which was initially estimating VIPAM at 1416.

While the Sector 10 controller was waiting for confirmation that the first B767 had passed the A310, she commenced the calculation for the time of passing for the A310 with the second B767. The controller's mental calculation was based on a 27-minute time difference derived from the revised VIPAM estimates of the A310 (1341) and the second B767 (1408). The controller calculated this time of passing as 1404 (this was erroneous as the correct time was 1353.30). The required standard was for the climbing aircraft (A310) to reach FL370 by a time 10 minutes before the time of passing. Based on the controller's calculated time of 1404, this requirement would have been 1354. However, because half-minutes are not normally used in these calculations, the controller rounded out on the side of safety and issued an instruction for the crew of the A310 to climb to FL370 with a requirement to reach FL370 by 1353.

At 1347, the crew of the B767 reported their position at DOTOD (a position on air route B220 south of the FIR boundary) and gave an updated estimate for VIPAM that was 2 minutes early. This new estimate had the effect of bringing the time of passing forward by 1 minute and the Sector 10 controller issued a new requirement for the crew of the A310 to reach FL370 by 1352. This requirement was correctly acknowledged.

At 1348, the crew of the A310 reported maintaining FL370. The aircraft passed at 1353. The Sector 10 controller had made a 10-minute error in the time of passing calculation and the separation standard had been breached.

Communication with the three aircraft in the relevant portion of air route B220 was through flight service HF channels. All transmissions and co-ordination procedures in regard to flight service requirements were adequate and in accordance with the appropriate instructions.

The Australian Manual of Air Traffic Services suggests that where separation is based on mathematical calculation, a cross-check of the results should be undertaken. On this occasion, the controller had intended to make such a cross-check using a navigation computer and had prepared the flight progress strip for the northbound B767 in readiness to carry out the second calculation. However, no such check was made. She had only checked her original calculation using the same mental method.

The workload on the Sector 10 controller had been high but most of the traffic separation conflictions had been completed, with co-ordination representing the bulk of the outstanding tasks at the time of the occurrence. However, the sector was still considered to be busier than normal.

ANALYSIS

Examination of the time of passing calculation indicated that using the 27-minute difference and the time of 1341 at VIPAM for the A310 (the point at which the controller based her separation calculation), the calculation should have resulted in a time of passing of 1354.30. This time would have then been rounded out to 1354 and then further amended to 1353 when the crew of the A310 reported at VIPAM at 1339. The difference of 1 minute in this time of passing calculation as compared to the controller's calculation (after subtracting the 10 minutes required by the separation standard and correcting the controller's 10-minute error), could not be adequately explained but was probably a safety net used by the controller when a half-minute was involved in the calculation. Having made the original 10-minute error, the controller made amendments in the single minute column and, because a cross-check was not carried out, the opportunity to remedy the mistake was lost.

The Sector 10 controller knew that a cross-check was required and had intended to carry out such a check for the time of passing involving the second B767. She could not say why this was not done but she was busy and had several items on her mind at the time. One such item was the option to use Port Moresby DME to establish a definite passing. She was unsure of being able to use a foreign navigation aid in Australian airspace and was discussing this option with other controllers.

Having made an error of 10 minutes in the time of passing calculation, certain factors may have reinforced the controller's perception that all was well. Firstly, the time of passing for the A310 and the first B767 had been correctly calculated and had worked as planned. Secondly, the initial estimated times at VIPAM between the A310 and the second B767, indicated that there was enough time for the change of level while maintaining separation standards provided that the crews of the A310 and the preceding B767 saw each other, and that the instruction for the climb was given as soon as those sighting reports were made. This situation would have provided 10 minutes for the crew of the A310 to complete their climb.

Additionally, the controller wanted to provide a good service and give the crew of the A310 the least possible delay for their climb.

However, irrespective of the times involving the A310, there was only a period of 20 minutes between the two northbound aircraft. This period was insufficient for the crew of the A310 to obtain a sighting and positive passing of the first B767, and then to climb to reach FL370 at least 10 minutes prior to passing the second B767.

The position reports that were subsequently made by the three crews indicated that all aircraft reached VIPAM earlier than initial estimates. This situation reduced the time available for the A310 to safely climb when using the controller's incorrect calculations. The aircraft actually passed at 1353.30.

SIGNIFICANT FACTOR

The Sector 10 controller did not carry out a cross-check of the time of passing as suggested by the Australian Manual of Air Traffic Services.

SAFETY ACTION

As a result of the investigation, Airservices Australia issued an instruction to draw the attention of controllers to the common error of carrying the "one" in any 10-minute calculation. They also introduced an additional tool for controller reference in the form of a Time of Passing Graph.