DHL 611 & Bashkirskie Avialinii 2937

The operational basics, regulations and procedures are defined in the Operations Manual, Part A, Section 8 dated 4 February 2002.

Flight crews should follow the RAs using established procedures unless doing so would jeopardize the safe operation of the airplane or positive visual contact confirms that there is a safer course of action. If an RA occurs, expeditiously accomplish the following:

If maneuvering is required, disengage the autopilot and smoothly adjust pitch and thrust to satisfy RAs.

The pitch must be adjusted to fly the airplane symbol just out of the red region(s) on the attitude indicator or to achieve a vertical speed just outside the red band(s) on the RA VSI/TRA (as installed). Adjust thrust as required to maintain desired speed.

Attempt to establish visual contact:

When clear of conflict, advise ATC and smoothly return to previous clearance.

Source: AX001-1-2/02, pp. 62 - 63

The operational basics, regulations and procedures for the handling of equipment and systems are defined in the Flight Operational Instruction for the TU154M („РУКОВОДСТВО ПО ЛЕТНОЙ ЭКСПЛУАТАЦИИ ТУ154M“).

En-route flight: After reaching the en-route flight level switch the range over to 40 NM and N (normal coverage). [This sentence is followed by the following items under the title “ATTENTION“:] 1. Prior to following the resolution advisory it is necessary to get contact with the conflicting traffic.

Source: AX001-1-2/02, pp. 64 - 65

When the controllers reported for duty at 17:50 hrs, they were not aware of the fact that during the night shift extensive sectorisation work on the sectors of the upper airspace was scheduled. Documents concerning the planned work were available for self briefing. They did not seize the opportunity to read them even though the duty schedule and their work contract allow time for such reading. The effects of this omission remain relatively insignificant as the documents did not include a description as to how the planned work would affect the availability of the technical equipment.

After the sectorisation work had started and the air traffic volume had decreased one of the controllers retired to rest in the lounge. Normally he would have returned to the control room early in the morning when air traffic increases, unless unusual circumstances would require his presence earlier. The spatial distance between the lounges and the control room prevents a quick alert of the second controller in conjunction with an immediate appearance. Thus the remaining radar controller had to assume the tasks of the radar planning controller (RP) and the radar executive controller (RE) and if necessary the tasks of the supervisor (DL) at the same time.

Officially this procedure did not exist, but had been in practise at ACC Zurich for many years. This arrangement made the night shifts for the controllers more comfortable. This is a way of proceeding which does not provide any redundancy of human resources so that procedural errors, wrong distributions of attention or the omission of important actions may lead to hazardous situations as nobody is there to notice these mistakes and to take corrective actions. It follows that the breaks prescribed could not be taken. Even though it was an unofficial procedure it was known to and tolerated by the management.

When the TU154M crew contacted Zurich at 21:30:11 hrs for the first time and also reported the flight level, the controller did not notice that the B757-200 had just reached the same flight level and that both airplanes were approaching each other at right angles. The distance between the two airplanes was still approximately 64 NM. If he had noticed the situation he would have instructed the TU154M crew to descend to FL 350. The control strip showed this altitude after Trasadingen VOR anyhow.

At the time the controller concentrated on a delayed Airbus A320 approaching Friedrichshafen airport. In doing so, he had to move to the adjacent workstation. He tried to phone Friedrichshafen several times. This was not possible due to a technical defect in the by-pass phone system but was time consuming and bound his concentration. He was not informed about the additional presence of a SYMA and therefore did not consider to involve him even though the SYMA would have been able to suggest an alternative.

Thus he neglected the control of the two other airplanes over a certain period of time. He was not alerted of the impending collision risk because the optical STCA was not available.

When the controller instructed the TU154M crew at 21:34:49 hrs for the first time to expedite descent to FL 350 the horizontal separation was practically already below 7 NM (exactly at 21:34:56, when the controller’s radio message ended).

The TU154M should have descended to FL 350 by 21:34:56 hrs to ensure a vertical separation of 1 000 ft in the RVSM airspace. To achieve this it would have been necessary to give the instruction to descend to FL 350 at 21:33:49 hrs at the latest - i.e. one minute before this instruction was actually given. This time is based on a normal rate of descent of approximately 1 000 ft per minute.

When the TU154M crew did not verbally respond to the first instruction to descend to FL 350, the controller repeated this instruction at 21:35:03 hrs more emphatically. As in his first instruction to descend he used the term “expedite“. The addition “expedite“ did not signalise, however, that the separation had already been infringed. The wording “I have crossing traffic“ which he used with his first instruction to descend did not match the urgency of the situation. It would have been better to use the term “immediately“ instead of “expedite“. A more detailed information about the conflicting traffic, e.g. “you have crossing traffic at 360 (or same level) in your 10 o’clock position“ or “from left to the right at 360 (or same level) distance: ........... NM“ would have been more appropriate in view of the short distance between the two airplanes (distance approximately 5.5 NM).

When the controller observed on the left monitor (RP) that the TU154M had initiated the descent he considered the problem solved and once again turned to the right monitor (RE). The reason was that the crew of the Airbus A320 approaching Friedrichshafen had just called again on 119,920 MHz. The two airplanes (B757-200 and TU154M) with the pertinent data were displayed on the right monitor as well. Only for radio transmissions on the different frequencies it was necessary to change workstations (between RP and RE).

When the controller moved to the workstation RE in order to deal with the A320, he concentrated his whole attention on the Airbus. Thus he neither noticed the descent of the B757-200 nor did he hear the radio message of the crew reporting a TCAS descent at 21:35:19 hrs.

When the controller had solved the problem with the Airbus A320, he once again concentrated his attention on the two airplanes. At this time, the collision had already happened and he saw the TU154M being displayed as a red point on the radar monitor indicating that a radar signal was not received any more. His radio calls addressed to the TU154M at 1:36:01, 21:36:23, and at 21:37:17 hrs remained unanswered. The B757-200 was no longer displayed on the radar monitor; it was not called by the controller.

It is the BFU's opinion that the controller was not in a position to safely execute the transferred and additionally assumed tasks.

A reason was the insufficient number of air traffic controllers during the night shift resulting from the duty schedule which did not ensure a continuous staffing of the workstations. It would have been the duty of the management and the quality assurance of the air navigation service company to realize these deficiencies and to take appropriate corrective actions. In addition the above-mentioned institutions tolerated the current practice applied to the conduct of the night shift.

Another reason was that priorities had not been evaluated properly. Dividing his attention on two events he found himself in a situation the effects of which he underestimated and ultimately could not control.

Source: AX001-1-2/02