Perimeter DH8C at Sandy Lake on Oct 19th 2022, tail strike on landing

Last Update: May 21, 2024 / 17:58:53 GMT/Zulu time

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Incident Facts

Date of incident
Oct 19, 2022

Classification
Accident

Aircraft Registration
C-GJYZ

ICAO Type Designator
DH8C

A Perimeter Aviation de Havilland Dash 8-300, registration C-GJYZ performing a flight from Pikangikum, ON to Sandy Lake,ON (Canada) with 28 passengers and 3 crew, landed on Sandy Lake's runway 29 when the tail contacted the runway surface. The aircraft rolled out without further incident.

The Canadian TSB reported the crew received a "TOUCHED RUNWAY" indicator. The TSB rated the occurrence an accident and opened an investigation (Class 3).

On May 21st 2024 the TSB released their final report concluding the probable causes of the accident were:

Findings as to causes and contributing factors

These are conditions, acts or safety deficiencies that were found to have caused or contributed to this occurrence.

1. Below 500 feet above ground level and while trying to intercept and maintain the appropriate approach path, the pilot flying varied the power setting between 57% and flight idle, likely owing to limited experience operating the aircraft type, and the result was an unstable approach.

2. Due to insufficient detail in the standard operating procedures and the absence of awareness training on stabilized approach criteria, the pilots did not recognize that significant variations in the power setting had made the approach unstable, and they continued the approach.

3. The pilot flying, who was relatively inexperienced on the DHC-8 and had received limited guidance on pitch awareness, made a pronounced pitch-up input during the flare. There was insufficient time for the pilot monitoring to arrest this action, and the aircraft’s aft fuselage consequently contacted the runway, causing significant damage.

Findings as to risk

These are conditions, unsafe acts or safety deficiencies that were found not to be a factor in this occurrence but could have adverse consequences in future occurrences.

1. If an air operator does not factor a pilot’s level of experience into a formal daily crew scheduling process, there is a risk of compromised safety margins due to the assignment of 2 pilots with limited experience in their roles to the same flight.

2. If air operators rely solely on flight crews to report hazards and risks to the company’s safety management system and do not actively monitor flight operations through flight data-monitoring capabilities, unsafe practices may not be identified, increasing the risk that they will continue.

The TSB analysed:

Flight crew pairing

The flight crew pairing for the occurrence flight met the regulatory requirements, given that both pilots had completed their training, consolidation period, line indoctrination, and line check. In effect, Perimeter Aviation LP (Perimeter Aviation) had provided the captain 195.5 hours of line indoctrination, and the first officer (FO) 73.9 hours, when only 20 hours are required. Although Perimeter Aviation’s management team had an informal practice of not pairing new pilots together on the monthly schedule, the company did not have a process in place during the SystemsOperations Control Centre’s (SOCC) daily rescheduling to avoid pairing pilots with limited experience in their roles to the same flight.

The day of the occurrence marked the captain’s 2nd flight day in the role of captain and on the occurrence aircraft type since his line check, and he had limited experience flying in the remote northern regions of Canada. The FOwith whom he had been paired had a number of flight hours on single-engine aircraft but very limited multi-engine experience. He was on his 3rd flight day since his line check. Like the captain, he had not conducted many flights in this region of Canada, and his experience in multi-crew environments was limited, as was his experience on the DHC-8.

Owing to the fact that the FO was relatively new to the aircraft type and the multi-crew environment, he required more supervision and coaching from the captain than an experienced FO would have needed. However, the captain also had limited experience in his role. Because of this, performing his role as a pilot-in-command led to a higher workload compared to that of a more experienced captain, leaving him with fewer cognitive resources that could be used to observe and support the FO.

As highlighted in the Air Transportation Safety Issue Investigation Report A15H0001, some air taxi operators have implemented a “green-on-green” policy to limit crew pairings of pilots who, despite having completed all their training, have not yet gained enough operational experience to mitigate the risks associated with pilots with limited experience in their roles flying together. This strategy is especially effective during times of high pilot turnover, when a higher number of inexperienced pilots are available to be scheduled.

Perimeter Aviation’s informal daily scheduling practice did not take into account pilot experience when pairing crew members together. Given the nature of Perimeter Aviation’s operations, the different types of expertise required, and its recent high pilot turnover, this practice can reduce safety margins.

Stabilized approach criteria

Air operators are not required by regulation to provide criteria for a stabilized approach in their procedures. However, given the history of approach and landing accidents (ALAs) and numerous studies, reports,and recommendations, most air operators, including Perimeter Aviation, have adopted a stabilized approach philosophy and incorporated stabilized approach criteria into their standard operating procedures (SOPs). Air operators develop their own stabilized approach criteria and often do so with the assistance of published guidance from Transport Canada.

The exact details of these adopted criteria often differ from one air operator to the next.

Perimeter Aviation’s SOPs in effect at the time of the occurrence included a section that described the requirements of a stabilized approach. It stated that the power setting should be appropriate for the aircraft configuration and that it should not fall below the minimum power setting for the approach as defined by the aircraft’s operating manual. An examination of de Havilland’s Dash 8 Series 300 Model 311/314/315 Operating Data manual revealed that it does not contain recommended power settings or any reference to a minimum power setting for an approach.

After a review of Perimeter Aviation’s Flight Crew Training Manual (FCTM), it was determined that the company’s pilots were not trained in recognizing stabilized approach factors. The de Havilland operating manual, to which the SOPs refer, does not provide the pilot with any power setting guidance, and consequently, it is the pilot who must determine the best power setting during an approach.

During the final approach on the occurrence flight, the aircraft met Perimeter Aviation’s stabilized approach criteria at the required altitude of 500 feet above airport elevation.

However, when the aircraft was below 500 feet above airport elevation, the pilot flying (PF) increased the power lever setting from 10% torque to 57% torque and, moments later, reduced it to flight idle. The large increase in engine power greatly affected the descent profile, resulting in a substantial increase in aircraft lift, a decrease in the rate of descent, and an increase in airspeed; causing the approach to become unstable. Given the trend in the aircraft’s airspeed and altitude, these large power variations would not have been required to intercept or maintain the appropriate approach path, and were likely a result of the pilot’s relatively limited experience operating the aircraft type.

Due to insufficient detail in the SOPs and the absence of awareness training on stabilized approach criteria, the pilots did not recognize that significant variations in the power setting had made the approach unstable, and they continued the approach.

Pitch control during the approach and landing

While the aircraft passed 0.2 nautical miles from the threshold, the FO, who was the PF, reduced the torque to flight idle while also decreasing the aircraft’s pitch angle to positive 2°. Immediately afterward, with a pronounced pitch-up control input, the pilot increased the pitch angle in the flare. At the same time, the torque began to gradually increase from flight idle.

The aircraft’s descent rate was 950 fpm when the main landing gear contacted the runway; the aircraft’s pitch angle increased rapidly through 5.8°. A fraction of a second later, the pitch angle reached 7.24°. The aircraft’s aft fuselage impacted the runway, approximately 350 feet from the threshold. At the moment of impact, the aircraft bounced to a height of approximately 1.5 feet while the pitch angle rapidly decreased to 2.2°.

Given the large and rapid increase in pitch, there was insufficient time for the captain, who was the pilot monitoring,to assist in the prevention of excessive pitch attitude, take control of the aircraft, or announce the pitch awareness calls to arrest the excessive descent rate.

It remains uncertain why the PF handled the aircraft in this manner, especially given that the SOPs caution pilots against it. Although the aircraft manufacturer had made a training video entitled “Dash 8-Q400 Pitch Awareness” and issued a service letter regarding Dash 8-Q400 pitch awareness training, this video was not used by Perimeter Aviation for its pilot training. However, some elements of the service letter, such as maximum pitch on landing, were incorporated in the SOPs.

Using safety management systems to address unstable approaches

In response to TSB RecommendationA14-01, Transport Canada published a Civil Aviation Safety Alert titled Using SMS to Address Hazards and Risks Associated with Unstable Approaches in June 2014.

In the absence of flight data monitoring (FDM), the publication recommends that air operators complete a review of their SMS database to verify the rate of occurrence of unstable approaches in order to perform a proactive assessment of the hazard.

The TSB’s investigation determined that from October 2021 to October 2022, Perimeter Aviation conducted approximately 34 000 aircraft movements, and of these, only 3 unstable approaches were reported to the company’s SMS.

The occurrence flight crew reported the occurrence as required under the company’s SMS. Perimeter Aviation’s Flight Operations department investigated the event and populated the SMS report file, detailing the investigation root cause analysis, causal factors, and a corrective/mitigation plan. As part of the company’s investigation, the department examined a similar report related to an aft fuselage strike, which identified unstable approach and landing as a factor. However, the Flight Operations department did not examine the recorded flight data from either the occurrence flight or the previously reported aft fuselage strike incident to determine whether the unstable approach was isolated to these 2 occurrences or whether it was a systemic issue.Additionally, because the company did not have an FDM program in place, no review of flight data had been conducted to determine the rate of incidence of unstable approaches within the company’s fleet.

When the TSB conducted an examination of Perimeter Aviation’s data from flight data recorders, it was discovered that 8.7% of the 246 recorded flights landed with pitch flare exceeding the air operator’s limit during the landing flare.

Excessive pitch flare resulting in a successful landing is not a reportable item in accordance with Perimeter Aviation’s SMS. Nonetheless, the data examined by the TSB demonstrate that hazards and risks are not always detected through reportable data.
Aircraft Registration Data
Registration mark
C-GJYZ
Country of Registration
Canada
Date of Registration
NnAAedibbfqgdnAn Subscribe to unlock
Certification Basis
DfhqAAAAfAdhbdihpcefgdf qgbchigdhcmpqkbcqjpgem Subscribe to unlock
TCDS Ident. No.
Manufacturer
Dehavilland
Aircraft Model / Type
DHC-8-314
ICAO Aircraft Type
DH8C
Year of Manufacture
Serial Number
Aircraft Address / Mode S Code (HEX)
Maximum Take off Mass (MTOM) [kg]
Engine Count
Engine Type
Main Owner
Mmlgmgljkdj cAe llimfjckmkgnigpljhbpfj dnicpAlde gihnkfbclkjjmfjpfkmApnihAqebmjk idkkdgjdjnflgffdmnniinindd ngpp jhhphqfmchklgljlmeq AAdiqAklfibdblAqq Ahmchcehmkhqpeghfe Subscribe to unlock

Aircraft registration data reproduced and distributed with the permission of the Government of Canada.

Incident Facts

Date of incident
Oct 19, 2022

Classification
Accident

Aircraft Registration
C-GJYZ

ICAO Type Designator
DH8C

This article is published under license from Avherald.com. © of text by Avherald.com.
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