RAF-Avia SF34 at Mariehamn on Feb 14th 2012, near collision with terrain

Last Update: September 30, 2013 / 13:57:43 GMT/Zulu time

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Incident Facts

Date of incident
Feb 14, 2012

Classification
Report

Airline
RAF-Avia

Aircraft Registration
YL-RAG

Aircraft Type
SAAB 340

ICAO Type Designator
SF34

A RAF-Avia Saab 340A on behalf of Nord Flyg, registration YL-RAG performing freight flight NEF-21 from Helsinki to Mariehamn (Finland) with 2 crew, had been cleared for the ILS Z approach procedure to runway 21 involving a DME ARC to intercept the localizer and to descend to 1800 feet, the captain (57, ATPL, 15,720 hours total, 200 hours on type) was pilot flying, the first officer (34, CPL, 390 hours total, 180 hours on type) was pilot monitoring. The aircraft intercepted the 10 nautical miles DME Arc, but turned prematurely off the Arc about 40 degrees off the extended runway center line onto a heading of 240 degrees towards the runway, possibly because of the side lobe of the localizer beam causing indications of the aircraft intercepting the localizer main beam. The controller noticed the aircraft had gone off the cleared approach path and queried the crew whether they were following their clearance, the crew replied affirmative, the aircraft faded below the radar horizon. The aircraft descended below 1800 feet MSL at about 400 fpm, the captain disconnected the autopilot at 1600 feet MSL and continued to fly manually. The aircraft turned right onto a heading approximately perpendicular to the extended runway center line and continued descent. The aircraft crossed the extended runway centerline at about 3.1nm before the runway threshold at 1000 feet MSL, the crew did not have the runway in sight. The controller cleared the aircraft to land on runway 21, the captain advised the first officer of his decision to land despite the first officer mentioning that they did not have the runway in sight nor did they have any indication of the localizer or glidepath. After crossing the extended runway center line the first officer noticed the course deflection indicator had come alive and advised the captain to turn left. The captain made a rapid deflection of both ailerons and rudder to the left and a rapid nose down input causing the aircraft to enter about 50 degrees of left bank, 19 degrees nose down in a side slip with rapidly accelerating sink rate. The GPWS activated alarms because of the excessive bank angle, excessive deviation below glide path and excessive terrain closure rate. The aircraft reached about 5000 feet per minute rate of descent at about 300 feet AGL. The controller saw the aircraft disappear behind rising terrain and trees. The GPWS activated "Terrain! Terrain! Whoop! Whoop! Pull Up!" The captain did not have the runway in sight and did not react initially to the GPWS alerts, he rather appeared to be following the first officer's guidance. The captain recovered the aircraft at 320 feet MSL or 150 feet AGL, according to Finland's AIB two seconds prior to impact and 2.7nm before the runway threshold. Rather than initiating a go-around the captain increased altitude only a little and continued the approach until visual contact with the runway was established with all 4 PAPI lights showing red. The aircraft subsequently landed safely on runway 21.

Finland's Onnettomuustutkintakeskus (Accident Investigation Board of Finland AIBF) released their final report concluding the probable causes of the serious incident were:

The serious incident was caused because the captain of NEF021 continued the approach in a situation which did not meet the requirements of a successful approach and landing. This degraded the flight crew’s situational awareness to the extent that the captain flew the aircraft into an unusual attitude and the crew lost control of the aircraft. This resulted in the risk of colliding with terrain.

As regards contributing factors Crew Resource Management was poorly handled, and the captain did not comply with the Company’s Operations Manual. Additionally, the crew did not follow the instrument approach procedure and ignored the warnings of the Ground Proximity Warning System.

The AIBF analyzed that the investigation could not establish with certainty why the aircraft turned off the Arc prematurely. The captain believed this was caused by a fault of the flight management computer, the first officer believed it was caused by the autopilot already have been armed for the approach and the side lobe of the localizer causing the autopilot to steer the aircraft off. The investigation ruled both scenarios out however, the APPR mode was armed only after the aircraft had turned left off the Arc. The investigation found a plausible scenario in which the VOR with the lead in course of 030 programmed would prompt the autopilot to begin intercepting the radial at a heading of 240 disengaging the NAV mode of the autopilot while following the programmed approach procedure. The crew did not monitor the continuation of the Arc to be followed until intercepting radial 030 but instead focussed on solving the perceived FMS problem.

The AIBF analyzed: "NEF021 continued to descend to 1800 FT MSL, below the Minimum Sector Altitude (MSA), with a heading which was approximately 40 degrees off the final approach track prescribed for the approach procedure. NEF021 should have maintained 1800 FT MSL. Since the aircraft was not stabilised on the approach track, they should have aborted the approach. NEF021 did not comply with the instrument approach procedure, nor did they have the runway or the approach lights in sight. The initial approach altitude prescribed for the approach is 1800 FT MSL; it is also the MSA. Descending below this altitude requires that the aircraft is established on the approach track and the glide path, or that the crew have the runway, its immediate surroundings or the approach lights in sight."

The AIBF continued:

The captain turned off the autopilot at 1600 FT MSL, turned right and manually continued to fly a heading which is at a 90 degree angle in relation to the final approach track, and descended to 1000 FT MSL. The pilots of NEF021 tried to get the runway in sight, but without success. While it might have been possible to see the runway in the prevailing conditions, their degraded situational awareness led them to look in the wrong direction for the runway.

The air traffic controller issued NEF021 a landing clearance which the co-pilot read back. The captain informed the co-pilot of the decision to continue the approach. The co-pilot replied that the runway is not in sight. This being the case, the captain did not have the grounds for making this decision. The co-pilot noticed that they had arrived on the final approach track at a 90 degree angle in relation to it and advised the captain to make a left turn. At this time they were 3.1 NM (approximately 5.7 km) from the threshold of RWY 21, flying at 1000 FT MSL.

The captain made a strong deflection with the aileron and the rudder to the left, in addition to which the captain deflected the elevator down. As a result of the flight control inputs the crew lost control of the aircraft and ended up in an unusual flight attitude in which the maximum bank angle was 50 degrees to the left and the maximum pitch angle was 19 degrees, nose down. The aircraft went into a sideslip with a rapidly accelerating sink rate. The Ground Proximity Warning System (GPWS) activated, warning the crew of an excessively steep bank angle, excessive deviation below the ILS glide slope and an excessive terrain closure rate. The sink rate of NEF021 peaked at approximately 5000 FT/min (25 m/s) at 300 FT AGL (90 M).

The captain managed to recover the aircraft at approximately 320 FT (98 m) MSL, i.e. approximately 150 FT (46 m) AGL. This happened about two seconds before they would have collided with the ground. They were 2.7 NM (5.0 km) from the threshold at this time.

The AIBF analyzed that evasive action (go-around) was required immediately upon the terrain GPWS alert. The captain stated that he did not hear the alert, and in the captain's perceiption the aircraft never was too low.

The AIBF characterized the crew cooperation between the two pilots with "cockpit authority gradient" and stated: "The investigation group believes that the cockpit authority gradient between the captain and the co-pilot of NEF021 was non-synergetic. The captain did not sufficiently communicate the autopilot mode selections to the co-pilot. The shortcomings in communication contributed to the inadequate airmanship, which materialised in degraded situational awareness and decision-making. Crew Resource Management was poorly handled and the captain did not comply with the Company’s Operations Manual." and summarized the first officer's actions: "The co-pilot actively attempted to comply with the Company’s standard operating procedures. The co-pilot, as per the interview, wanted to abort the approach but, according to previous experience, the co-pilot did not believe that the captain would agree to this. It is likely that the co-pilot’s limited flight experience also factored in. Moreover, the co-pilot believed that any attempts to actively interfere with the captain’s flying, such as taking over the controls, would have spelled trouble later on."

With respect to the air traffic controller the AIBF stated: "As per the air traffic controller’s statement, NEF021 appeared to be turning approximately 90 degrees to the left after it was cleared for approach, as seen on the ATS monitor. Since the air traffic controller assumed that NEF021 had deviated from the route given in the air traffic control clearance the controller requested the crew of NEF021 to confirm that they were tracking the initial approach route. However, the crew replied that they were on the initial approach route. Soon after this the symbol of the aircraft on the monitor became imprecise as regards azimuth information, and then it faded out below the radar horizon. At this time the controller could only assume that NEF021 was trying to follow the route given in the air traffic control clearance. The air traffic controller saw NEF021 crossing the final approach track at a 90 degree angle in relation to the final approach, following which it made a steep turn towards the left and disappeared behind the terrain and trees. At this time the controller believed that NEF021 would collide with the ground. Nonetheless, NEF021 re-appeared from behind the treeline. The air traffic controller did not want to distract the pilots by ordering a goaround."
Incident Facts

Date of incident
Feb 14, 2012

Classification
Report

Airline
RAF-Avia

Aircraft Registration
YL-RAG

Aircraft Type
SAAB 340

ICAO Type Designator
SF34

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