Porter DH8D at Sault Ste Marie on May 26th 2013, hard landing and tail strike

Last Update: February 13, 2015 / 20:42:50 GMT/Zulu time

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Incident Facts

Date of incident
May 26, 2013

Classification
Accident

Aircraft Registration
C-GLQO

ICAO Type Designator
DH8D

Airport ICAO Code
CYAM

The Canadian TSB released their final report concluding the probable cause of the accident was:

Findings as to causes and contributing factors

- Neither crew member identified that the airspeed had dropped below landing reference speed; the flight no longer met the requirements of a stabilized approach, and an overshoot was required.

- The pilot monitoring did not identify the decreasing airspeed and increasing descent rate in time to notify the pilot flying or intervene.

- In response to the pilot monitoring’s warning to add power, the pilot flying pitched the nose up beyond the limits stated in the standard operating procedures and the manufacturer’s pitch awareness training.

- The high rate of descent coupled with the high nose-up attitude of the aircraft resulted in the hard landing that compressed the struts and allowed the tail to strike the runway.

Findings as to risk

- If standard operating procedures do not clearly define the requirements for a stabilized visual approach, there is an increased risk that continued flight could result in a landing accident.

- If standard operating procedures do not clearly define the duties of the pilot monitoring, there is an increased risk that unsafe flight conditions could develop.

The TSB reported the first officer (2,484 hours total, 134 hours on type) was pilot flying, the captain (8,410 hours total, 3,835 hours on type) was pilot monitoring. The first officer had completed line training, during which training captains had identified several areas requiring improvement amongst them pitch/power management during approaches and "the elimination of large power changes to chase speed in descent".

The flight was the only flight of the day for the crew. The flight had been uneventful until the aircraft was on final approach, Vref had been computed to 121 KIAS. The crew performed a visual approach to Sault Ste Marie's runway 30 when the first officer disengaged autopilot at about 2500 feet MSL. The aircraft was descending on final approach varying slightly above and below the 3 degrees glidepath with responses by slight variations of pitch and power.

The aircraft descended through 500 feet AGL at 127 KIAS (Vref+6) on the extended center line of the runway, the captain made the "stabilized" call which was acknowledged by the first officer. Shortly afterwards the aircraft began to drift above the glidepath, the first officer applied pitch down inputs and the airspeed increased, however, the aircraft continued to drift above the glidepath nearing the 3.5 degrees angle. The first officer reduced engine power from 13% to 5% (flight idle) and pitched the nose down slightly, the airspeed began to decay rapidly and the rate of descent increased. The captain focused on the visual did not notice the power change, the accelerating rate of descent and decreasing airspeed. Descending through 90 feet AGL the airspeed dropped below Vref, descending through 40 feet AGL over the runway threshold the airspeed had decayed to 116 KIAS (Vref-5) and the aircraft had descended below the 2.5 degrees approach angle. The captain noticed that the aircraft was too low and the rate of descent had increased to 900 fpm and called for power. The first officer increae the pitch angle, then applied power just as the aircraft touched down at a recorded 7.3 degrees nose up (the TSB made the annotation that due to the sampling interval the actual attitude might have peaked at a higher angle) and +3.05G. 7.3 degrees nose up with gear fully or near fully compressed is consistent with a tail strike.

The TSB reported: "The examination of the aircraft revealed impact and scuff marks on the skin, structural stiffeners and longerons of the lower part of the aft portion of the fuselage (Photo 1). Repairs to the aircraft included replacing the damaged fuselage skin along with the damaged structural stiffeners and longerons."

The TSB analysed that the "stabilized" call was justified as all stabilized approach criteria laid out in the standard operating procedures of the operator were fulfilled.

The TSB analysed: "As the aircraft passed through approximately 90 feet HAT, the airspeed dropped below VREF and continued to decrease. At the same time, the vertical speed was increasing above -800 fpm and the aircraft was drifting below the ideal 3° PAPI glide path. The PM did not notice the increased rate of descent, most likely because he was monitoring the visual approach out the window at this point and not the aircraft instruments. As a result, no call-out for a go-around, as required by the company SOP, was made by the PM when the airspeed dropped below VREF. Continuing the approach when an aircraft does not meet the criteria for a stabilized approach is cited by the Flight Safety Foundation as being a contributing factor in 66% of approach and landing accidents and serious incidents. Neither crew member identified that the airspeed had dropped below VREF; the flight no longer met the requirements of a stabilized approach, and an overshoot was required."

The TSB analysed: "The company SOP defines the criteria for a stabilized approach; however, one item that is not mentioned is glide path when using visual glide scope indicators such as the PAPI. There are indications for instrument landing system (ILS) glide slope deviation, which would be applicable during an ILS approach, but no limits for the visual approach. The FDR data clearly indicate that the aircraft was constantly deviating above and below the glide path after the autopilot was disconnected, yet by company SOP the aircraft met all the criteria for a stabilized approach while passing through 500 feet HAT. The only defined parameter that made the approach unstable was when the indicated airspeed dropped below VREF at 90 feet HAT."
Aircraft Registration Data
Registration mark
C-GLQO
Country of Registration
Canada
Date of Registration
Bhmbbgmcnldgqfdgbf Subscribe to unlock
Certification Basis
FAkbjpqfjmdmgibdefflmdbAgleqlh d d kniqchemcm Subscribe to unlock
TCDS Ident. No.
Manufacturer
Dehavilland
Aircraft Model / Type
DHC-8-402
ICAO Aircraft Type
DH8D
Year of Manufacture
Serial Number
Aircraft Address / Mode S Code (HEX)
Maximum Take off Mass (MTOM) [kg]
Engine Count
Engine Type
Main Owner
NqqjjldjegdgbmkigihidcAibiidmhmpjenc fgcqqlljkdpchjbpplcAkmlbjilqlkkgcpfchljgAjjhjlAhnl A Subscribe to unlock

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

Incident Facts

Date of incident
May 26, 2013

Classification
Accident

Aircraft Registration
C-GLQO

ICAO Type Designator
DH8D

Airport ICAO Code
CYAM

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