Creebec DH8A at Val d'Or on Oct 26th 2023, near collision with terrain
Last Update: October 29, 2025 / 11:44:20 GMT/Zulu time
Incident Facts
Date of incident
Oct 26, 2023
Classification
Report
Airline
Air Creebec
Flight number
YN-238
Departure
Chisasibi, Canada
Destination
Val d'Or, Canada
Aircraft Registration
C-FLSX
Aircraft Type
De Havilland Dash 8 (100)
ICAO Type Designator
DH8A
The Canadian TSB released their final report concluding the probabe causes of the serious incident were:
- When the holding pattern was being programmed at the IKDOB waypoint before the area navigation approach to Runway 18 at Val-d’Or Airport using the global navigation satellite system, by default, the flight management system suggested the preprogrammed holding pattern at the IKDOB waypoint that was the last waypoint of the flight plan. Therefore, when the DTO HOLD [direct to hold] function was activated, given that there were no further waypoints on the flight management system flight plan after the holding pattern, the aircraft was going to maintain its last heading, unbeknownst to the pilots, rather than conduct the approach.
- Given that there were no further waypoints on the flight plan when the aircraft exited the holding pattern, the flight management system maintained the aircraft on its current course, which diverged from the final approach path by 48°, complicating the manoeuvre needed to re-establish the aircraft on the approach path.
- When the approach was being reprogrammed in the flight management system, maintaining a divergent heading for 44 seconds, combined with a late descent, resulted in the aircraft arriving at the final approach waypoint at 180 KIAS in a clean configuration (flaps and landing gear retracted). At that point, it was no longer possible to slow down the aircraft to the 120 knots indicated airspeed meet the company’s stabilized approach criteria at 1000 feet above ground level.
After the aircraft passed the final approach waypoint, it continued to turn right on a divergent vertical and lateral track and left the obstacle clearance area, risking a collision with obstacles or terrain.
- Given the high workload and the loss of shared situational awareness regarding the change in the approach plan, the pilot not flying asked the area control centre for clearance to conduct a go-around, while the pilot flying was continuing the descent at approximately 1300 fpm as the aircraft passed the company’s stabilized approach gate at 187 knots indicated airspeed, i.e., 67 knots faster than the target speed.
- Approximately 25 seconds after communications began with the area control centre, alerts were generated by the terrain awareness and warning system and a go-around was initiated. At its lowest point, the aircraft was 405 feet above ground level, flying at an airspeed of 192 knots indicated airspeed (i.e., 72 knots above the target speed), in a clean configuration, approximately 1 nautical mile to the right of the approach path, and 1 nautical mile from the runway threshold.
- Initial and recurrent training on the flight management system did not enable the flight crew to recognize the particular subtleties of the system programming, causing a discrepancy between the flight crew’s expectations and the aircraft’s behaviour, and causing difficulties with in-flight programming, all leading to a delay in completing critical flight actions.
Findings as to risk:
- If holding patterns are not aligned with the final approach path, the manoeuvre to conduct the approach is more complex, and should an unexpected situation arise, the increase in workload may reduce the overall situational awareness of the approach and thus create a risk that critical tasks will not be performed.
- If cockpit voice recorder data are not kept after an incident or accident, it may not be possible to identify and communicate safety deficiencies and learn potential lessons.
The TSB analysed:
Holding pattern design
Holding patterns that are part of an approach procedure generally have a course that is aligned with the approach path to minimize the manoeuvres needed to remain on that approach path. However, when the area navigation approach to Runway 18 using the global navigation satellite system (RNAV [GNSS] RWY 18) was designed at Val-d’Or Airport (CYVO), the holding pattern at IKDOB was oriented 48° from the final approach path because there was a blasting area north of IKDOB. Because of this orientation, when an aircraft exits the holding pattern, it must manoeuvre to join the final approach path. This manoeuvre is normally managed by the FMS and performed by the autopilot. However, if an unexpected situation arises and the turn is not carried out by the autopilot, as was the case in this occurrence, the flight crew must react quickly to redirect the aircraft toward the final approach path so that the approach path can be intercepted.
Any unexpected situation generates additional tasks because the flight crew must determine what happened and correct the anomaly. This situation increases the workload at a time when it is already high because of the number of tasks to be completed during an approach (begin the descent, reduce speed, and modify the aircraft configuration before reaching the stabilized approach gate). When faced with a high workload, pilots might concentrate on information and tasks that they deem the most critical, to the detriment of other elements. Consequently, there is a risk that their overall situational awareness of the approach will be reduced.
Adding a holding pattern to the flight plan in the flight management
system
While inbound for CYVO, the flight crew had programmed the RNAV (GNSS) RWY 18 approach in the FMS flight plan. During the descent from flight level 200, the Montréal Area Control Centre (ACC) told the flight crew that a priority medical evacuation (MEDEVAC) flight was going to land at CYVO before them, and instructed them to proceed directly to the initial approach waypoint IKDOB and conduct the published holding pattern. The pilot not flying (PNF) set the DTO [direct to] function to the initial approach waypoint IKDOB and the FMS navigated directly to IKDOB (the 5th item on the flight plan). Two other IKDOB waypoints were on the FMS flight plan: one at the beginning of the approach (the 7th item on the flight plan), and one at the end of the missed approach (the 12th item on the flight plan).
Then, when the PNF attempted to add a holding pattern at the IKDOB waypoint before the approach (the 5th item on the flight plan), by default, the FMS suggested the preprogrammed hold at the IKDOB waypoint at the end of the missed approach (the 12th item on the flight plan). On the FMS holding pattern definition page, there was nothing in the field displaying IKDOB that indicated which of the 3 IKDOB waypoints on the flight plan was being used. Given that the PNF did not change the IKDOB waypoint provided by default, when the DTO HOLD [direct to hold] function in the bottom left of this page was activated, the FMS navigated to the IKDOB missed approach holding pattern corresponding to the final waypoint on the flight plan (12th item on the flight plan). On the FMS main navigation page (NAV 1/3), it was not possible to see that there were no further waypoints after the holding pattern.
Given that the FMS flight plan did not contain any further waypoints after the holding pattern, the FMS could no longer follow the approach path after the holding pattern was exited.
Execution of the holding pattern
When the occurrence aircraft entered the holding pattern, the MEDEVAC aircraft, which was number 1 for the approach, conducted a go-around because of the poor weather conditions.
However, because the MEDEVAC aircraft was not ready to conduct a 2nd approach, the ACC directed it outbound to a point west of CYVO, where it went into a holding pattern to allow other holding aircraft to conduct their approach to CYVO.
Exiting the holding pattern
Twelve minutes after entering the holding pattern, the occurrence flight crew received approach clearance from the ACC, which asked if the flight crew could proceed directly to the approach from their position or if they needed to fly an additional circuit in the holding pattern. The PNF was aware that at 6000 feet above sea level, the aircraft was 1590 feet above the 3° approach slope, and that the descent would need to be faster than usual to reintercept the approach slope. Believing that the approach was programmed in the FMS and that the autopilot would navigate to the final approach path, the PNF felt that the altitude above the approach slope was not a problem and proceeded directly to the approach without flying an additional circuit in the holding pattern.
During the 30 seconds of communications with the ACC, which ended 7 seconds before the aircraft passed IKDOB, the PNF activated the PROCEED [proceed] function in the FMS to exit the holding pattern, expecting the aircraft to follow the approach path. This activation generated messages on both FMS systems, which required acknowledgment by each pilot, at a time when the flight crew was about to coordinate the beginning of the approach and the workload was high. Given that the aircraft had just passed the final waypoint on the FMS flight plan when it exited the holding pattern, the FMS maintained the aircraft on its current track, which diverged from the final approach path by 48°. The 2 horizontal situation indicators showed the course maintained by the FMS, which was straight ahead, with no lateral deviation showing on the course deviation indicator. The aircraft did not have a navigation screen showing the aircraft’s position on a map, which would be another tool available to help the flight crew build their situational awareness of the aircraft’s position.
Recovering the approach
The aircraft was on a divergent track above the optimal approach slope, which required an immediate left turn and a faster-than-normal descent, while the aircraft’s speed had to be reduced to extend the wheels and flaps. Without FMS guidance to begin the approach, the flight crew had to immediately complete several tasks at the same time. A high workload is known to cause attention narrowing or channelling, which can lead to the omission or delay of certain tasks.
The PNF immediately concentrated on re-establishing the approach navigation guidance in the FMS, which reduced the cognitive resources available to them to monitor the actions of the pilot flying (PF), who was less experienced, and to reassess the decision to conduct the approach from 6000 feet above sea level. Initially, the PNF attempted to use the instrument landing system, but given that the very high frequency omnidirectional range (YVO) distance measuring equipment at Val-d’Or was not working that day, the PNF
reprogrammed the RNAV (GNSS) RWY 18 approach in the FMS.
When the approach was activated (ACT APPR), both horizontal situation indicators aligned themselves with the final approach path (182°). Given that the aircraft was flying to the right of the approach path and above the approach slope, their course deviation indicators showed a full deviation to the left, and their slope indicators were fully down.
In addition, the heading entry field of the CMD HDG [command heading] function in the FMS synchronized itself with the aircraft’s heading and maintained the aircraft’s current course while waiting for confirmation of the heading entered using CMD HDG.
Beginning of the descent
The PNF realized that the descent had not begun and selected the minimum sector altitude of 3900 feet in the altitude preselect controller. ALT SEL [altitude preselect] mode needed to be selected by the PF for the autopilot to level the aircraft off at this altitude, which was not done. The PNF, believing that the minimum obstacle clearance altitude was correctly programmed, went back to programming the FMS so that the aircraft would turn left to intercept the final approach path.
Twenty-four seconds after exiting the holding pattern, the PF began the descent at a fixed descent rate with the autopilot VS [vertical speed] mode, and the airspeed gradually increased from 161 to 204 knots indicated airspeed (KIAS), at which point the power was reduced to the minimum.
In the meantime, the PNF once again attempted to establish a track to intercept the final approach course in the FMS.
Intercept function in the flight management system
The FMSs installed in Air Creebec’s DHC-8 fleet presents a specific issue in that the heading entry field in the CMD HDG function in the FMS is not continuously synchronized with the selected heading, which is displayed on the HSI.
The aircraft’s heading is automatically proposed and highlighted in the entry field of the CMD HDG function in the FMS when the approach is activated. Therefore, as was the case for the occurrence aircraft, if the aircraft’s heading diverges from the final approach path when the approach is activated, the proposed heading will not make it possible to intercept the final approach path, and NO INTCPT [no intercept] will replace the INTERCEPT function. In such a situation, the pilot must calculate and manually enter a heading that will enable interception of the final approach path so that the INTERCEPT function will be displayed.
There is a high risk of error in calculating the new intercept heading and in entering the heading in the FMS because these tasks increase the workload at a critical point in a flight when the workload is already heavy.
Left turn to final approach waypoint URVIX Pilots must process and incorporate multiple sources of information in a dynamic and complex environment. When they are faced with information that is contrary to their expectations, their reaction may be slower and at times inappropriate. In this occurrence, the PNF, who was faced with a heavy workload and wanted to begin a left turn toward the final approach path, accepted the heading of 231° proposed by the CMD HDG function in the FMS, which was the aircraft’s heading at the time. Given that the FMS was still maintaining the aircraft’s heading, the autopilot HDG [heading] mode (without the FMS) was used to turn left.
During these attempts to establish an intercept course using the FMS, the aircraft remained on a divergent heading for 44 seconds. This delay in beginning the turn and descent, combined with the aircraft’s acceleration to 204 KIAS at 1 minute 31 seconds from final approach waypoint URVIX, made it even more difficult to rejoin the approach.
Smooth coordination of the actions of the 2 flight crew members required effective communication to maintain a shared situational awareness. To that end, the pilots needed to communicate the information available and ensure that they had a shared understanding of the situation, despite the high workload. An analysis of the flight crew’s actions suggests that they attempted to recover the approach in a sequential manner, which may indicate a less effective coordination of task sharing. It is possible that, given the PF’s low level of experience, the PF did not fully understand the plan and expectations of the PNF (who was the captain) and was waiting for instructions from the PNF to begin the descent and left turn without FMS guidance. However, without cockpit voice recorder data, the investigation was unable to assess task coordination and communications between the 2 pilots.
When the aircraft passed final approach waypoint URVIX, it was 0.24 nautical miles to the right of the final approach path, 500 feet above the approach slope, and flying at an airspeed of 180 KIAS in a clean configuration (flaps and landing gear retracted). The aircraft had to maintain its 1300 fpm descent rate to rejoin the approach slope, and reduce its speed below 158 KIAS to extend the landing gear, then below 148 KIAS to extend the flaps. At that point, it was no longer possible to slow the aircraft to the 120 KIAS target speed and meet Air Creebec’s other stabilized approach criteria at 1000 feet above ground level (AGL), which the aircraft would reach in 42 seconds.
When the aircraft was passing final approach waypoint URVIX, the flight crew selected the autopilot NAV [navigation] mode to transfer the aircraft’s navigation to the FMS in the hopes of intercepting the final approach path. The aircraft began a right turn, which is what was expected. However, instead of intercepting the final approach path of 182°, the aircraft continued turning right onto the heading of 231° entered using the CMD HDG [command heading] function in the FMS. With all the information displayed on navigation page NAV 1/4, the flight crew did not notice that the FMS was still in HDG SEL [heading selected] mode, with the CMD HDG set to 231°, or that the INTERCEPT function was replaced by NO INTCPT in grey (Figure 17, Section 2.2.2 The intercept function in the flight management system).
In general, rejoining the lateral track is a priority during an instrument approach so that the aircraft remains in the obstacle clearance area, given that the flight crew cannot see the ground. Therefore, when the aircraft’s heading passed the desired track (182°) while it was turning right, and still under instrument meteorological conditions, the PNF took action in the FMS to have the aircraft turn left and head directly toward the runway. This additional workload caused the PNF to lose the bigger picture of the approach and the aircraft left the obstacle clearance area on final approach while it was still in a high-speed descent, increasing the risk of collision with obstacles or terrain.
Coordination of the go-around
While the PNF was busy establishing a path toward the runway, engine power increased from idle (0%) to 43% while the airspeed was 171 KIAS, or 13 knots above the maximum speed for lowering the landing gear and 23 knots above the maximum speed for the 1st flap selection. The increase in power suggests an intent to reduce or cease the descent. However, the aircraft maintained a fixed descent rate of approximately 1300 fpm, and the airspeed gradually increased from 171 to 187 KIAS.
When the aircraft began to turn left toward the runway, the PNF, who had made the decision to conduct a go-around, contacted the ACC for clearance to perform a go-around because of a navigation problem. At that point, the PNF was not sure of the exact position of the MEDEVAC aircraft that was holding west of CYVO, given that the occurrence aircraft did not have a navigation screen that could have shown its position and the position of other aircraft in the vicinity. Faced with this uncertainty, the PNF wanted to ensure that there was no conflict or risk of collision with the MEDEVAC aircraft. The ACC, which did not have a radar showing airborne aircraft, was unable to see that the occurrence aircraft was west of the final approach path, and therefore did not grasp the urgency of the situation. With a 2nd aircraft unable to land at CYVO even though weather conditions were reported to be above the published minima, and with other aircraft waiting to conduct their approach to CYVO, the ACC asked the occurrence flight crew to state their intentions. The communications lasted 32 seconds.
Nine seconds after the PNF began communicating with the ACC, the aircraft flew below the stabilized approach gate of 1000 feet AGL at 187 KIAS in a clean configuration, still at a descent rate of approximately 1300 fpm.
To meet the stabilized approach criteria, the aircraft’s descent rate must not exceed 1000 fpm, the target speed must be 120 KIAS (+10 to -5 KIAS), and the aircraft must be on the approach vertical and lateral trajectory in a landing configuration (landing gear extended and flaps at 15°).
Two seconds after passing the stabilized approach gate, power was partially reduced to 20%. This action indicates that the PF was still focused on the descent and speed reduction, which limited the PF’s ability to understand the communications between the PNF and the ACC about the PNF’s intention to conduct a go-around.
The flight crew’s heavy workload decreased their ability to coordinate their actions, and led to a loss in their shared situational awareness regarding the change in the approach plan to conduct a go-around. Their heavy workload also reduced their overall awareness of the situation on approach, so they did not notice when they passed the stabilized approach gate or anticipate the risk of collision with terrain while the aircraft was continuing its descent.
Consequently, while the ACC was giving specific instructions for the go-around, TAWS alerts were being generated and the FMS automatically displayed the information page showing an imminent collision with terrain. The flight crew immediately began a go-around before communications ended.
Cockpit voice recorder On the occurrence flight, the flight crew did not realize how close the aircraft was to the ground or how serious the situation was; therefore, they did not turn off the cockpit voice (and audio) recorder. These data were therefore overwritten by recordings from subsequent flights.
Given that the recording of TAWS alert–related data was also lost, the investigation was unable to determine the types of alerts or the precise times that they occurred.
Communication between pilots is critical when the workload is high: they must share the information available so that they can maintain the same understanding of the situation and thus anticipate and coordinate their actions and act cohesively and effectively.
Other data available regarding aircraft and FMS inputs showed that attempts to recover the approach as the aircraft was exiting the holding pattern were carried out sequentially, which delayed the descent and the left turn to intercept the final approach path. However, without the data from the cockpit voice recorder, the investigation was unable to assess how the captain, who was the PNF, managed and coordinated the tasks to be completed given the high workload. The investigation was also unable to determine if the PF’s level of experience played a role in the occurrence. Consequently, it is possible that some safety issues, especially those related to flight crew cohesion and effectiveness when dealing with a heavy workload, may not have been identified by the investigation.
Flight management system programming training
Initial and recurrent training in the simulator include programming the FMS in all phases of flight, but not necessarily in the specific conditions encountered during the approach on the occurrence flight.
Despite the PNF’s training and experience, and although the PF had recently completed initial training (5 months earlier), the flight crew did not recognize that the programmed holding pattern was at the final IKDOB waypoint, or the last missed approach waypoint (12th item on the flight plan) rather than at the IKDOB waypoint before the approach (5th item). Therefore, when they were exiting the holding pattern, the flight crew did not realize that the FMS had no further waypoints and was going to maintain the diverging track rather than conduct the RNAV (GNSS) RWY 18 approach as anticipated.
Then, as the flight crew flew toward final approach waypoint URVIX, given all the information displayed on navigation page NAV 1/4 (Figure 18), the flight crew did not notice that the FMS was still in HDG SEL mode and that NO INTCPT was displayed in grey. Consequently, the flight crew did not realize that the final approach path would not be intercepted once the autopilot NAV mode was selected. The flight crew members were not expecting the aircraft to turn right on the heading of 231° entered using the CMD HDG function, and deviate from the final approach path.
In this occurrence, the flight crew had to deal with the unexpected behaviour of the FMS, which required a number of actions to attempt to recover the final approach path. These actions delayed the coordination and completion of other actions that were critical to the flight, such as re-intercepting the approach slope, reducing speed, and configuring the aircraft for landing. A thorough understanding of the indications on the FMS pages, which are at times subtle, is important to cut down on the time needed to interpret the displayed indications, especially in a situation where there is a heavy workload.
Aircraft Registration Data
Aircraft registration data reproduced and distributed with the permission of the Government of Canada.
Incident Facts
Date of incident
Oct 26, 2023
Classification
Report
Airline
Air Creebec
Flight number
YN-238
Departure
Chisasibi, Canada
Destination
Val d'Or, Canada
Aircraft Registration
C-FLSX
Aircraft Type
De Havilland Dash 8 (100)
ICAO Type Designator
DH8A
This article is published under license from Avherald.com. © of text by Avherald.com.
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