Carpatair F100 at Gallivare on Apr 6th 2016, overran runway on landing

Last Update: March 10, 2017 / 17:26:34 GMT/Zulu time

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Incident Facts

Date of incident
Apr 6, 2016

Classification
Incident

Airline
Carpatair

Flight number
2N-4856

Aircraft Registration
YR-FZA

Aircraft Type
Fokker 100

ICAO Type Designator
F100

Airport ICAO Code
ESNG

A Carpatair Fokker 100 on behalf of Nextjet, registration YR-FZA performing flight 2N-4856 from Arvidsjaur to Gallivare (Sweden) with 50 passengers and 5 crew, landed on Gallivare's runway 30 at 21:30L (19:30Z) but could not stop before the end of the runway and overran the end of the runway by about 4 meters coming to a stop with the main gear past the runway end and nose gear on soft ground. There were no injuries, the aircraft received minor if any damage.

The airport needed to be closed for the recovery of the aircraft.

The occurrence aircraft is still on the ground in Gallivare about 17.5 hours later.

On Apr 8th 2016 Sweden's Statens Haverikommission (SHK) reported the aircraft made an instrument approach to runway 30 but went off the runway coming to a stop with both nose and main gear off the runway. The occupants disembarked via stairs. The occurrence is being investigated by the SHK.

Gallivare features a runway 12/30 of 1714 meters/5622 feet length, no approach lights and no instrument procedures exist for runway 12, runway 30 features an ILS approach and approach lights.

On Mar 10th 2017 te SHK released their final report concluding the probable causes of the serious incident were:

The serious incident was caused by the gradual decrease of the conditions for a safe landing, which was not perceived in due time.

Contributing factors:

- The airspeed did not decrease from 50 feet’s height to touch-down.

- The reported friction coefficients were probably unreliable.

- The wheel brakes were probably not fully applied due to the initial yaw disturbance.

- The reverse rpm increased only 20 seconds after touchdown.

The SHK reported the captain (42, ATPL, 8,285 hours total, 3,496 hours on type) was pilot flying, the first officer (24, CPL, 770 hours total, 514 hours on type) was pilot monitoring. The crew performed an instrument approach to Gallivare's runway 30, the actual procedure was not mentioned, the flaps were set to full, the speed brake was extended, Vref was 122 KIAS. About 10 minutes prior to landing AFIS reported: "wind 010 degrees, 5 knots, visibility 1 500 meters in snow and rain, vertical 800 feet, temp 0, dew point also minus 0, QNH 994" ... "and we are still sweeping the runway, we have braking action 36, 34, 35, contamination 1 mm slush". About 3 minutes prior to landing AFIS reported the runway was clear, winds from 030 degrees at 6 knots, runway lights were at 100% intensity.

The crew made visual contact with the runway lights at 500 feet, the captain disengaged the autopilot, the aircraft crossed the runway threshold at 50 feet at 134 KIAS and touched down hard in the touch down zone at 134 KIAS, bounced once and veered slightly to the left. Brakes were immediately applied, the thrust reversers deployed at the same time, the lift dumpers extended. The captain reported he immediately applied reverse thrust, the flight data recorder showed however that the engines accelerated for reverse thrust only 20 seconds after touchdown when the aircraft slowed through 50 KIAS and reached 75/65% rpm. The aircraft crossed the runway end and came to a stop with the main gear 6 meters past the runway end. The crew radioed AFIS about the runway overrun, AFIS alerted emergency services.

A stair was placed at the aircraft's main door and passenges disembarked normally onto the runway end safety area and were bussed to the terminal.

The aircraft sustained minor damage mainly consisting of tyre damage and fan blade damage as result of using reverse thrust at a restricted rpm range exceeding the maximum time span permitted.

The SHK analysed:

About ten minutes before the approach the pilots were informed that the friction coefficient was 0.36, 0.34 and 0.35, the temperature 0 and the dew point minus 0 and that the runway was contaminated with 1 mm of slush. This means, as presented in section 1.16.2, that the reported friction coefficients probably were unreliable.

The absence of specific information in the operator's manuals on the unreliability of friction coefficients under such circumstances can explain that the pilots did not take any special action for this reason.
The aircraft was configured in accordance with the operator's procedures for short runways which meant the use of full flaps (42 degrees) and speed brake. Callouts regarding the speeds associated with the extension of the flaps to 25 and 42 degrees were not recorded by the Cockpit Voice Recorder (CVR).

The pilot in command stated that the speed was VREF + 5, corresponding to 127 knots, over the runway threshold. However, according to DFDR-data, the indicated airspeed over the threshold was 134 knots (12 knots over VREF) and was unchanged until touch-down. The excess speed is within the limits of the general criteria for stabilised approach, but does not meet the aircraft manufacturers or the operator’s criteria indicating that the runway threshold speed shall be VREF. The lack of communication between the pilots associated with the extension of full flaps may explain why the speed was not set to the correct values.

The absence of speed reduction at touch-down is probably due to a late thrust reduction to idle. According to the aircraft manufacturer, the thrust reduction shall be performed over the runway threshold.

DFDR data indicate a hard landing with a bounce, and displacement in yaw which was probably caused by an insufficient flare and high speed, combined with crosswind. The pilot in command has stated that braking was initiated immediately and that the reverse thrust was activated. However, the pilot in command delayed the increase of reverse thrust due to the yaw.

The pilot in command has stated that reverse thrust soon thereafter was increased maximum emergency reverse. Maximum rpm for emergency reverse is 95.5 % N1. DFDR-data indicate, however, that the reverse rpm only increased to about 75 % N1 and 65 % N1 for the left and right engine, which took place about 20 seconds after touchdown and at a speed of about 50 knots. Since the engine speed was in the restricted area cautions were activated. CVR recordings did not reveal any callouts concerning the engines rpm in this area.

The low reverse rpm together with the low speed meant that the effect of the reverse was almost absent.

DFDR-data indicate that the longitudinal acceleration during the rollout averaged -0.07 G until the reverse rpm started to increase. This indicates that the wheel brakes had no effect during period, which either might be caused by the absence of brake application, or by a very low friction coefficient. The pilot’s statement that the brake temperature indicated low values after landing is also indicates that the wheel brakes had no effect.

SHK is therefore unable to determine whether the slow deceleration was due to the absence of brake application, or to the friction coefficient being lower than measured.

The absence of maximum emergency reverse immediately after touch-down can be explained by the yaw displacement that occurred. The delay of about 20 seconds is probably due to the lack of engine instruments monitoring. As mentioned above, the approach briefing did not mention any information about the use of reverse and brakes, which may have contributed to reduced attention in these areas.

There are no standard procedures regarding cockpit cooperation, such as callouts, when it comes to monitoring of deceleration and reverse rpm after landing. In SHK’s opinion, this is a shortcoming that can contribute to this type of events.

Metars:
ESNG 062050Z 05008KT 1200 SN BR VV006 00/M00 Q0992
ESNG 062020Z 05007KT 1500 -SN BR VV009 00/M00 Q0993
ESNG 061950Z 05007KT 1100 R30/P1500N -SN VV007 00/M00 Q0993
ESNG 061920Z 05008KT 1300 R30/P1500N SNRA VV008 00/M00 Q0994
ESNG 061850Z 05007KT 2700 -SN VV011 00/M00 Q0994
ESNG 061820Z 05007KT 3000 -SN FEW007 OVC011 00/M00 Q0995
ESNG 061750Z 04006KT 2900 -SN VV010 00/M00 Q0995
ESNG 061720Z 05007KT 2000 -SN VV009 00/M00 Q0996
ESNG 061650Z 05006KT 3000 -SNRA VV017 00/M01 Q0996
ESNG 061620Z 07007KT 4700 -SN BKN012 OVC015 01/M01 Q0996
ESNG 061550Z 07008KT 9999 -RASN BKN013 OVC017 01/M01 Q0997
ESNG 061520Z 08009KT 9999 SG FEW012 OVC018 01/M01 Q0997
Incident Facts

Date of incident
Apr 6, 2016

Classification
Incident

Airline
Carpatair

Flight number
2N-4856

Aircraft Registration
YR-FZA

Aircraft Type
Fokker 100

ICAO Type Designator
F100

Airport ICAO Code
ESNG

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