Transportation Safety Board of Canada AVIATION OCCURRENCE REPORT A98H0002

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AVIATION OCCURRENCE REPORT
A98H0002
LOSS OF SEPARATION
BETWEEN
AIR CANADA BOEING 747-400 C-GAGN
and
AIR FRANCE AIRBUS A340 F-GLZL
NORTH ATLANTIC, ST. JOHN’S, NEWFOUNDLAND 125nm S
20 JULY 1998
Transportation Safety Board
of Canada
Bureau de la sécurité des transports
du Canada
The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of
advancing transportation safety. It is not the function of the Board to assign fault or determine
civil or criminal liability.
Aviation Occurrence Report
Loss of Separation
Between
Air Canada Boeing 747-400 C-GAGN
and
Air France Airbus A340 F-GLZL
North Atlantic, St. John’s, Newfoundland 125 nm S
20 July 1998
Report Number A98H0002
Summary
Air France flight 033 (AFR033), an Airbus A340 aircraft, was en route from Houston, Texas, USA,
to Paris, France, at flight level (FL) 370 with a routing of WHALE, BANCS, and latitude 46°N
longitude 50°W (Oceanic Track "X"). Air Canada flight 870 (ACA870), a Boeing B747 aircraft, was
en route from Montreal, Quebec, to Paris at FL 370 with a routing of MIILS, COLOR, and
latitude 47°N longitude 50°W (Oceanic Track "W"). ACA870 was re-cleared from MIILS direct to
latitude 45°N longitude 50°W (Oceanic Track "Y"). The new routing placed ACA870 on a
converging track with AFR033. Approximately 30 miles west of the BANCS intersection, both
aircraft received and responded to traffic avoidance and collision advisory system (TCAS)
resolution advisories (RA). A loss of separation occurred at approximately 0213 Coordinated
Universal Time (UTC) when the two aircraft closed to approximately 400 feet vertically and 1.9
miles horizontally. The required separation in the airspace for these aircraft is 5 miles
horizontally or 1000 feet vertically.
Ce rapport est également disponible en français.
Table of Contents
1.0 Factual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 History of the Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Injuries to Persons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Damage to Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Other Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 Personnel Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5.1 Air Traffic Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5.1.1 Air Traffic Controllers’ Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 Aircraft Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6.1 Air Canada Boeing 747 C-GAGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6.2 Air France Airbus A340 F-GLZL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.7 Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.8 Aids to Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.9 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.10 Control Procedures - General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.10.1 Flight Progress Strip Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.10.2 Duties of Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.10.3 Radar Control Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.10.4 Radar Monitoring Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.10.5 Conflict Alerting Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.11 Flight Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.0 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Conflict Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1 Information Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.2 Attentive Flight Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3 Conflict Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.0 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 Causes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Appendices
Appendix A - Track Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Appendix B - Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1 See Glossary for all abbreviations and acronyms.
2 All times are Coordinated Universal Time (UTC) unless otherwise stated. (UTC equals
Newfoundland daylight time plus 2 hours and 30 minutes).
1.0 Factual Information
1.1 History of the Flight
Air France flight 033 (AFR033)1, an Airbus A340 aircraft, was en route from Houston to Paris at
flight level (FL) 370 with a routing of WHALE, BANCS, and latitude 46°N longitude
50°W(Oceanic Track "X"). Air Canada flight 870 (ACA870), a Boeing B747 aircraft, was en route
from Montreal to Paris at FL 370 with a routing of MIILS, COLOR, and latitude 47°N longitude
50°W (Oceanic Track "W"). ACA870 was re-cleared from MIILS direct to latitude 45°N longitude
50°W (Oceanic Track "Y"). The new routing placed ACA870 on a converging track with AFR033.
The two aircraft were being controlled by the Gander Area Control Centre (ACC) high domestic
controllers responsible for the combined sector BANCS and south, the two south-easternmost
sectors of the Gander domestic airspace, in which the coast-out points BANCS and RAFIN are
located (see Appendix A, Figure 1). ACA870, with 265 passengers and a crew of 14, had been
issued an amended oceanic clearance by clearance delivery prior to handoff to the BANCS radar
controller. ACA870 contacted the radar controller at 0151:152, outside the geographic boundaries
of the BANCS sector, and crossed the sector boundary at 0207. Position estimate information was
provided by ACA870 to the radar controller indicating that the aircraft was level at FL 370 and
estimating latitude 45°N longitude 50°W at 0227.
AFR033, with 235 passengers and a crew of 14, had received an oceanic clearance and had been
handed off to the radar controller at 0158:32. AFR033, established on the route WHALE direct to
BANCS, was level at FL 370, and estimating BANCS at 0217. The aircraft track during this
portion of the flight was approximately 076° magnetic.
At approximately 0211, as ACA870 approached 40 nm west of the BANCS intersection en route
to latitude 45°N longitude 50°W, the radar controller contacted ACA870 and advised that radar
service would terminate at longitude 50°W and to contact Gander radio on frequency
126.9 megahertz. At this time, ACA870 was approximately 9 nm from AFR033 and converging on
a track of 116° magnetic. No action was taken by the radar controller. Approximately one minute
and thirty seconds later, at 0212:33, while the radar controller was communicating with another
aircraft, ACA870 received a TCAS RA and attempted to make radio contact with the radar
controller, but was cut off by another transmission. Seven seconds later, at 0212:40, ACA870
declared Pan, Pan, Pan. The radar controller issued a clearance to descend to FL 360. ACA870
replied that they were climbing as a result of the RA and that they were on a collision course.
The radar controller advised ACA870 to follow the advisory.
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Immediately thereafter, AFR033 declared Pan, Pan, Pan and advised the controller that the
aircraft was descending as a result of a TCAS RA (see Appendix A, Figure 2). AFR033 received an
initial TCAS traffic advisory (TA) at 0211:34 and an RA to descend at 0212:47. Recorded radar
data of the occurrence shows AFR033's altitude to have been 36,900 feet at 0212:49, 36,700 feet at
0212:54, 36,700 feet at 0212:59, and 36,400 feet at 0213:03. (Valid recorded radar data may differ
from aircraft-reported altitude by plus or minus 200 feet.) Aircraft data provided by Air France
show the altitude of AFR033 as 36,788 feet at 0212:59 with a downward velocity of 1,790 feet per
minute, and 36,384 feet at 0213:30. The time between the onset of the RA and initiation of
descent with the autopilot off was two seconds.
On receiving the TCAS RA, ACA870 began an immediate climb to FL 380 and reached that
altitude approximately 50 seconds after commencement of the climb. Seventeen seconds after
the end of the AFR033 Pan, Pan, Pan transmission, ACA870 advised that they were directly
overhead the Air France aircraft and that the two aircraft would have collided.
1.2 Injuries to Persons
There were no injuries.
1.3 Damage to Aircraft
There was no damage to either aircraft.
1.4 Other Damage
There was no other damage as a result of this occurrence.
1.5 Personnel Information
1.5.1 Air Traffic Controllers
Controller Position Radar Controller
Age 36
Licence ATC
Experience
- as a Controller
- as an IFR Controller
- in Present Unit
8 years
8 years
8 years
Hours on Duty Prior to Occurrence 6
Hours off Duty Prior to Work Period 58
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Controller Position Data Controller
Age 34
Licence ATC
Experience
- as a Controller
- as an IFR Controller
- in Present Unit
9 years
9 years
9 years
Hours on Duty Prior to Occurrence 3.75
Hours off Duty Prior to Work Period 38
1.5.1.1 Air Traffic Controllers’ Experience
The sector in which the loss of separation occurred, BANCS, was staffed by a data controller and
a radar controller in accordance with unit staffing requirements. The team supervisor, in
keeping with normal practice, was working at another sector providing a relief break for a
controller. The radar controller had eight years’, and the data controller nine years’, experience
in air traffic control. Both controllers were appropriately licenced and qualified. The radar
controller had been on duty for six hours, and the data controller three and three quarters hours,
since the beginning of their shifts. The radar controller was on the first shift of his work cycle,
having completed two days off. The data controller had been off the previous day but had
reportedly worked 16 shifts in the previous 18 days, 7 of which had been overtime shifts. Such a
schedule is within the terms of the collective agreement provided one day off is provided after
nine consecutive days of work. The traffic volume at the time of the occurrence was described as
moderate to heavy. All necessary equipment was serviceable and being used.
1.6 Aircraft Information
1.6.1 Air Canada Boeing 747 C-GAGN
Manufacturer Boeing
Type and Model 747-400
Year of Manufacture Not applicable
Serial Number Not applicable
Engine Type (number of) 4
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1.6.2 Air France Airbus A340 F-GLZL
Manufacturer Airbus Industrie
Type and Model A340
Year of Manufacture Not applicable
Serial Number Not applicable
Engine Type (number of) 4
1.7 Meteorological Information
The weather was clear in the vicinity of the occurrence.
1.8 Aids to Navigation
All navigation aids were reported to be operating normally.
1.9 Communications
Normal means of communication were serviceable.
1.10 Control Procedures - General
1.10.1 Flight Progress Strip Manipulation
Flight progress strips are maintained by controllers and contain written information on the
status and intentions of aircraft passing through a sector. Directions for the marking and
manipulation of flight progress strips are contained in the NAV CANADA Air Traffic Control
Manual of Operations (ATC MANOPS), Part 9, and in the Gander ACC Operations Manual, High
Level Domestic, Strip Writing Procedures.
The original flight planned routing for ACA870 was from North American route N49A to MIILS
direct to COLOR and then to latitude 47°N longitude 50°W (Oceanic Track “W”)
(see Appendix A, Figure 1). The original flight progress strip, designated D1 for ACA870, was
posted under the COLOR header in the flight progress board of the appropriate sector. When
the oceanic clearance was changed necessitating a reroute, the D1 strip was amended by the
data controller in the COLOR sector by stroking out the fix identifier COL ( COLOR) and
writing in the new fix identifier, RFN ( RAFIN), which is the fix associated with latitude 45°N
longitude 50°W. In accordance with the Gander ACC Operations Manual, article 4.1.6.2, the strip
was then passed to the affected sector, BANCS. Subsequently, a new oceanic clearance strip was
printed at 0138 together with an amended sector strip designated D2 and passed to the BANCS
sector for posting under the RAFIN header. There was no traffic on the route from RAFIN to
latitude 45°N longitude 50°W at FL 370 which conflicted with ACA870.
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ACA870, now rerouted and known locally as a cutter, crossed several other active tracks,
including the WHALE-to- BANCS track which was very active on the night of the occurrence,
from the northwest to the southeast. ACA870 passed approximately 13 nm abeam BANCS, while
its closest approach to RAFIN was approximately 28 nm. There was no flight progress strip
printed for posting under the BANCS header. There is no requirement for such a posting in local
procedures, and there is no provision for the printing of an extra strip for this purpose. Aircraft
joining southern oceanic tracks from the North American Midwest generally cut southeastbound
across other established tracks, and are a relatively common occurrence for Gander
controllers.
The flight route of AFR033 took it directly over BANCS and on to latitude 46°N longitude 50°W
to follow Oceanic Track “X”. The flight progress strip for AFR033 was posted under the BANCS
header.
The Gander ACC Operations Manual, High Level Domestic, Strip Writing Procedures, article 2.6,
directs that “When aircraft are cleared direct and this results in the aircraft going abeam a fix, the
fix shall have “A/” written to the upper left of the affected fix ....” The flight progress strip used
by the BANCS and south sector for ACA870 was not marked with the “A/” to the upper left of
the fix indicator, RFN, on either the D1 or D2 strips. Article 2.4 specifies that “If a particular route
requires attention: ... the fixes to the right of the aircraft ident shall have a box placed around
them on all strips.” No box was placed around the fixes to the right of the aircraft identification
on either the D1 or D2 flight progress strips of ACA870. Article 8.3.2 directs that “If there is a
radar confliction also include fix under which the traffic is posted.” There were no other fixes
indicated on the flight progress strips of ACA870 to indicate that there might be a radar conflict
with traffic on the BANCS track.
1.10.2 Duties of Controllers
The Gander ACC Operations Manual, Part 4, High Domestic Sector Procedures, specifies the
responsibilities of controllers as follows:
4.1.2 Sector controller(s) is/are responsible for all IFR aircraft operating within the
airspace assigned to their sectors.
4.1.4 When a Radar and Data controller are assigned to the same sector, the radar
controller is primarily responsible for the flow of sector traffic. The sector workplan and
the overall strategy shall be determined jointly. It is recognized that during some traffic
situations one controller may not be immediately aware of all actions initiated by the
other - in this case each controller is responsible for his actions.
4.1.6 When assigned to a Sector, the data controller’s primary role is to facilitate the
flow of flight data between Radar sectors.
Prior to the occurrence, the data controller was fully occupied facilitating the flow of flight data
between sectors, and he was not aware of activities as they unfolded on the radar controller’s
radar indicator module (IM). The flight progress strips of the two aircraft were posted under
different coast-out fixes, and because the data controller’s primary responsibility was to facilitate
the flow of flight data between Radar sectors, he was not specifically aware of the proximity of
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AFR033 and ACA870 at the same altitude as they approached BANCS. The radar controller was
primarily responsible for the flow of sector traffic, and other than keeping flight progress strips
updated by checking altitudes and estimates, he performed his separation function using only
the IM. Supervisors, even when not otherwise occupied performing relief duties for other
controllers, are not expected to provide close inspection and quality control of controllers in
these circumstances, because it is not possible for the supervisor to be cognizant of the control
actions taken by controllers in all the sectors of a specialty.
1.10.3 Radar Control Methods
The NAV CANADA ATC MANOPS, article 471.1, directs controllers to apply separation by
consistent reference to, and use of three elements fundamental to effective control: plan
separation, execute the selected plan, and monitor progress to ensure continued applicability of
the plan.
To assist in the identification of potential aircraft conflicts, the radar controller has at his or her
disposal a tool known as the Predict Track Line (PTL). This electronic device displays a line on
the IM showing a predicted direction and expected travel distance of an aircraft present position
symbol based on the time in minutes entered by the controller. It was the radar controller’s habit
to use this tool on a regular basis to detect traffic conflicts. On the night of the occurrence, the
radar controller had used the PTL regularly prior to the approach of the occurrence aircraft, but
did not detect the intersecting flight paths of ACA870 and AFR033.
1.10.4 Radar Monitoring Methods
In TSB Occurrence No. A96A0138, an altered routing put two aircraft that were under radar
control, a Boeing 747 and a Boeing 767 with a total of 502 persons on board, on converging
courses at the same altitude until they were about three miles apart. At that time, the crews of
both aircraft received and reacted to TCAS RAs and manoeuvred to avoid collision. The radar
controller was unable to explain why he was unaware of the conflict between the two aircraft.
In TSB Occurrence No. A97H0007, two aircraft, a Boeing 727 and a Canadair CL-600,
approaching head-on under radar control on direct off-airway routes, were involved in a risk of
collision. In this instance, only one of the aircraft was fitted with TCAS. The RA and subsequent
declaration by the crew of their avoidance action were the only warnings provided.
In TSB Occurrence No. A97C0144, a Boeing 737 under radar control was given permission to
deviate north of the flight planned route to avoid weather. The actual position of the aircraft did
not correspond with that indicated by the positioning of the aircraft’s flight progress strip and
the radar controller, occupied in resolving a problem on another part of the IM, did not detect
the imminent conflict with an opposite-direction DC-9 during his monitoring of the IM. The
Boeing 737 received a TCAS RA and manoeuvred to avoid the other aircraft approaching
head-on.
In TSB Occurrence No. A99H0001 (investigation in progress), two opposite-direction Boeing 767
aircraft under radar control, with a total of 206 persons on board, were involved in an air
proximity occurrence when the radar controller cleared one aircraft to climb through the other’s
altitude. Both aircraft received TCAS RAs.
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In each of the above occurrences, the aircraft were being provided with radar monitoring and
the radar controller had spoken to one of the involved aircraft shortly before the conflict, and in
each instance the radar controllers were unable to explain why they had not detected the
approaching conflict. Controller fatigue or exceptional distractions, other than normal traffic
conflicts, were not identified as findings in any of the completed investigations.
NAV CANADA Functional Goal Number 1 encourages controllers to provide full-time attentive
flight monitoring and flight information services. Effective scanning techniques as required in
ATC MANOPS, article 901.8, are covered in the recently inaugurated Situational Awareness
Module training package, which has been administered to approximately 80 percent of air traffic
control units. Gander controllers had not yet received this training at the time of the occurrence.
There is no formal lesson plan in basic or regional air traffic control training designed to teach
controllers specific radar monitoring techniques or best practices. During basic radar simulation
training, however, instructors are directed to include as teaching points information to avoid
concentrating too long on one situation during radar scanning, because other situations may
require attention as well.
1.10.5 Conflict Alerting Tool
The original performance specifications for the ATC radar data processing system (RDPS)
software included provisions for aircraft conflict detection and alerting. During testing in the late
1980s and early 1990s, the RDPS conflict alert function was found to have several faults and was
not considered acceptable for operational use. This function is still not in operational use today.
The Canadian Aviation Safety Board (CASB), the TSB’s predecessor, recommended in 1990 that,
The Department of Transport accelerate all technical initiatives with a potential for
providing controllers with automated conflict prediction and alerting.
CASB 90-36
Transport Canada accepted the recommendation and advised that “Minimum Safe Altitude
Warning/Conflict Alert would be implemented as the Radar Data Processing Systems are
brought online with the introduction of the Radar Modernization project beginning in June
1990.” In early 1997 NAV CANADA advised that the unavailability of the conflict alert feature of
RDPS was an on-going issue. The conflict alert feature of RDPS was still under development,
and it was hoped that it would be available with the 700 version of RDPS software then
scheduled for release in the fall of 1997. NAV CANADA advised in early 1998 that software
testing of this functionality was under way and on-site test was planned for the fall of 1998.
Operational acceptance was expected to be lengthy. Software testing of the conflict alert
functionality is still under way but is expected to be completed in 1999, followed by site testing
in Toronto, Ontario, and Edmonton, Alberta. The Minimum Safe Altitude Warning (MSAW)
portion is not expected to be included in this site test procedure. NAV CANADA, in its
Corporate Safety Plan 1998/99, stated that it is committed to “the national installation of
Minimum Sector Altitude Warning Systems/Conflict Alert (MSAW/CA) on existing surveillance
systems.”
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1.11 Flight Recorders
Flight recorder information was provided by Air Canada and Air France to determine aircraft
responses on receipt of the respective TCAS RAs. That information was included in section 1.1
above.
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2.0 Analysis
2.1 General
The radar controller was aware, at least from ACA870's radio position reports if not from the
information contained on the flight progress strip, that this aircraft was what is known as a
“cutter”, and that the flight path of the aircraft would cut across the tracks of other aircraft
proceeding eastbound to the ocean. This situation was described as being relatively common for
controllers in southern sectors of the Gander airspace. As well, the radar controller
communicated with ACA870 one minute and twenty seconds prior to the Pan, Pan, Pan call by
the crew. At the time of the communication, the two aircraft were approximately 9 nm apart and
on a converging course. The radar controller should have detected and resolved the conflict
between AFR033 and ACA870 well before the risk of collision occurred.
2.2 Conflict Detection
2.2.1 Information Exchange
Some of the factors which actively contributed to the radar controller not detecting the
approaching conflict include the following:
• There was no strip posted at BANCS for ACA870, and there is no provision for the
automatic printing of such a strip in the flight progress strip processing software in use
in Gander.
• Notwithstanding the direction in Gander ACC Operations Manual, article 4.1.4, that
the sector workplan and the overall strategy shall be determined jointly, there appears
to be no procedure which encourages team planning and problem solving.
• The division of work and the very different work focus of the radar controller and the
data controller encourage independent work. This is acknowledged in the Gander
ACC Operations Manual, article 4.1.4, where controllers are reminded that “It is
recognized that during some traffic situations one controller may not be immediately
aware of all actions initiated by the other ....” The next reminder emphasizing that
“each controller is responsible for his actions” is an accepted philosophy; however, it
contributes little to enhancing safety.
2.2.2 Attentive Flight Monitoring
The TSB investigations noted in section 1.10.4 bear resemblances to this occurrence in that in
each referenced occurrence, the radar controller did not detect aircraft conflicts displayed on the
IM. While strip scanning for potential traffic conflicts is necessary, the increasing prevalence of
direct off-airway routes, which do not lend themselves to the relatively structured environment
for which flight progress strips were designed, puts a premium on the necessity to actively and
constantly monitor the IM. While NAV CANADA does provide direction to all controllers on
scanning techniques, that subject matter is more oriented to flight progress strip scanning
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procedures than to definable techniques associated with how to maintain full-time attentive
radar flight monitoring. In this occurrence, the radar controller’s full-time attentive flight
monitoring procedure did not meet the level of attentiveness required to provide an adequate
level of safety to the aircraft under his control, and, as a result, the radar controller did not
recognize the conflict and did not provide air traffic control radar separation between the two
aircraft.
2.2.3 Conflict Resolution
Devising a specific separation plan is predicated on recognizing that a situation exists that
requires specific action. The benefits of adding specific markings to strips in accordance with
articles 2.4 and 8.3.2 of the Gander ACC Operations Manual are restricted to their use as memory
aids in that the use of the warnings presupposes that potential conflicts have been recognized. If
no conflict is identified, no warning markings are added. Review of the flight progress board for
conflicting traffic at common points and full-time attentive flight monitoring of the IM are often
the triggering events that enable radar controllers to recognize potential conflicts and to begin
the action planning process. Where there is no obvious conflict indicated on the flight progress
board (the two aircraft were not posted under a common point and none of the required
markings were on either of the flight progress strips), or where the conflict is overlooked during
the monitoring process, the radar controller may not devise a specific separation plan and thus
may perform no specific separation actions. Where task design does not encourage effective
team problem solving, the necessary team planning step may not be accomplished, and the
radar controller in his or her tactical control decisions becomes the single, ground-based point of
defence against airborne collisions. That defence broke down when the radar controller did not
identify the conflict during his monitoring of the tactical situation on the IM. The team
supervisor was unable to intervene as a final level of quality control because he was occupied
controlling in another sector, and, in any case, his duties preclude detailed knowledge of the
control actions of all the controllers in all the sectors of the specialty. There was no procedural or
technological defence in the design of this air traffic control process to contain this situation once
the radar controller missed the developing conflict.
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3.0 Conclusions
3.1 Findings
4. The controllers involved in this occurrence were qualified and current.
5. All equipment available to the controllers was serviceable and being used.
6. Staffing in the sector met unit standards. The supervisor was working in another sector
at the time of the occurrence.
7. The workload was assessed as heavy.
8. The radar controller did not devise an active separation action plan because he did not
recognize the need for one.
9. The flight progress strips for ACA870 were not marked with the various symbols
specified in the Gander ACC Operations Manual indicating that the flight required
special attention.
10. The sector controllers’ performance of their duties, seemingly in conformance with the
directives and the task design in the Gander ACC Operations Manual, did not lend
itself to effective sector team problem solving and separation planning, which resulted
in the loss of an effective defence.
11. The placement of the two flight progress strips under two separate fixes did not overtly
warn the radar controller that the two aircraft at the same altitude would be in close
proximity in the vicinity of one of those fixes.
12. There was no rigorous training on radar monitoring methods provided to these
controllers in basic air traffic control training or during refresher or specialty training
after initial qualification.
13. The TCAS RAs received by the crews of ACA870 and AFR033 provided the only
warning and successful resolution to the traffic conflict.
14. Though planned for implementation to meet traffic needs in the early 1990s, a
functioning automated conflict alert tool was not available.
15. The Canadian Aviation Safety Board (CASB), the predecessor to the TSB, in 1990,
recommended that the air traffic service provider accelerate all initiatives with a
potential for providing controllers with automated conflict prediction and alerting.
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3.2 Causes
The radar controller did not recognize the traffic conflict between ACA870 and AFR033, and, as a
result, did not apply the required radar separation criteria between the two aircraft. The fact that
the flight progress strip procedures did not provide a flight progress strip for posting at the fix
nearest the point of conflict; there was no basic or follow-on training provided to the radar
controller in effective radar monitoring techniques; there was no realistic human back-up to the
radar controller’s activities; and there was no technological back-up in the form of an automated
conflict alert tool contributed to this occurrence.
This report concludes the Transportation Safety Board’s investigation into this occurrence. Consequently,
the Board, consisting of Chairperson Benoît Bouchard, and members Maurice Harquail, Charles Simpson
and W.A. Tadros, authorized the release of this report on 29 September 1999.
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Figure 1 - Routes of ACA870 and AFR033. BANCS and south sector shaded.
Figure 2 - Aircraft positions at 0212:54. Horizontal distance 1.9 nm, vertical distance 400 feet
Appendix A - Track Diagrams
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Appendix B - Glossary
ACA870 Air Canada flight 870
ACC Area Control Centre
AFR033 Air France flight 033
ATC air traffic control
CASB Canadian Aviation Safety Board
COL COLOR (fix)
FL flight level
IFR instrument flight rules
IM radar indicator module
MANOPS Manual of Operations
MSAW Minimum Safe Altitude Warning
MSAW/CA Minimum Sector Altitude Warning Systems/Conflict Alert
N north
nm nautical mile
PTL Predict Track Line
RA resolution advisory
RDPS radar data processing system
RFN RAFIN
S south
TA traffic advisory
TCAS traffic avoidance and collision advisory system
TSB Transportation Safety Board of Canada
UTC Coordinated Universal Time
W west
° degree