Qantas A332 at Melbourne on Mar 8th 2013, EGPWS alert during visual final approach

Last Update: July 9, 2015 / 14:58:11 GMT/Zulu time

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Incident Facts

Date of incident
Mar 8, 2013

Classification
Incident

Airline
Qantas

Flight number
QF-455

Aircraft Registration
VH-EBV

Aircraft Type
Airbus A330-200

ICAO Type Designator
A332

A Qantas Airbus A330-200, registration VH-EBV performing flight QF-455 from Sydney,NS to Melbourne,VI (Australia), was cleared for a visual approach to Melbourne's runway 16 about 8nm northeast of the aerodrome when at 18:50L (07:50L) the EGPWS issued a terrain warning prompting the crew to go around from about 1400 feet MSL. The crew told ATC they were going around due to a "Terrain - Pull up!" alert, the controller told the crew they had been down to 2000 feet and cleared the aircraft to climb to 4000 feet. The aircraft positioned for another approach to runway 16 that concluded with a safe landing.

Australia's Transportation Safety Board opened an investigation into the occurrence, that the ATSB rated a serious incident.

On Jul 9th 2015 the ATSB released their final report concluding the factors into the serious incident were:

Contributing factors

- During the latter stages of a visual approach the captain assessed the aircraft’s flight path using glide slope indications that were not valid, resulting in an incorrect assessment that the aircraft was above the nominal descent profile.

- The combination of the selection of an ineffective altitude target while using the auto-flight open descent mode and ineffective monitoring of the aircraft’s flight path resulted in a significant deviation below the nominal descent profile.

- The flight crew’s action to reduce the aircraft's rate of descent following detection of the altitude deviation did not prevent the aircraft descending outside controlled airspace and the activation of the enhanced ground proximity warning system.

Other factors that increased risk

- Qantas provided limited guidance on the conduct of a visual approach and the associated briefing required to enable the flight crew to have a shared understanding of the intended approach. [Safety issue]

- The captain’s performance capability was probably reduced due to the combined effects of disrupted and restricted sleep, limited recent nutrition and a cold/virus.

Other findings

- The flight crew acted to reduce the aircraft's rate of descent prior to the activation of the enhanced ground proximity warning system (EGPWS) and conducted a recovery manoeuvre immediately after the EGPWS ‘PULL UP’ warning.

The ATSB reported that the captain (ATPL, 21,907 hours total, 2,272 hours on type) woke up the night prior to the occurrence flight at about 05:00L due to throat irritation. The throat irritation worsened during the day together with further symptoms of a cold, due to the throat irritation the captain did not eat breakfast or lunch that day. The first officer (ATPL, 10,027 hours total, 983 hours on type) was well rested following a 31 hours rest period.

The captain was pilot flying into Melbourne. Prior to reaching the top of descent the crew briefed the standard LIZZI 6 Alpha arrival route, due to experience during earlier landing the captain expected to be "short tracked" from waypoint HORUS to the Final Approach Fix 6nm from the runway threshold, and briefed the short track approach as well, which was programmed as secondary flight plan into the FMGS.

As the aircraft was about to begin the descent towards Melbourne, ATC cancelled all speed restrictions, requested a high speed descent and advised of short tracking. The crew accepted the high speed descent, amended the flight plan with the new speeds and commenced the descent in managed mode. Later into the descent the crew was cleared to descend to 5000 feet and offered the short track HORUS to FAF, the crew accepted the short track, the secondary flight plan was activated.

The captain recollected that after activation of the secondary flight plan the aircraft was about 1400 feet above the vertical profile, the track miles to short down were reduced by 5nm by the short track. The captain selected open descent mode and deploying half of the speed brake, which increased the rate of descent to 4000 fpm. The aircraft was cleared to 4000 feet MSL and levelled off at that altitude about 17nm before touchdown and reduced speed being 2000 feet below the computed nominal 3 degree glidepath and about 1500 feet above the lower limit of controlled airspace. After cleared to descend to 3000 feet the captain selected again open descent and to activate the approach phase in the FMGS to enable continued deceleration to approach speed.

About 14nm before touchdown the aircraft was just capturing 3000 feet when ATC cleared the aircraft for a visual approach, the aircraft was 45 degrees of the final approach course, 800 feet above lower limit of controlled airspace and 1800 feet below the 3 degrees glidepath.

The captain selected 1000 feet MSL target altitude and activated open descent, the ATSB wrote: "The first officer reported not hearing the captain verbalise these changes and was unaware that the altitude selector had been changed." The landing gear was selected down, the first stage of flaps extended and the aircraft maintained 180 KIAS as requested by ATC, the aircraft descended at about 2000 fpm.

The ATSB wrote: "The captain reported observing the aircraft’s instrument landing system (ILS)6 glide slope deviation indicator on the primary flight display and that it was indicating the aircraft was above the glide slope. This appeared valid to the captain and was consistent with his earlier assessment of the aircraft being high relative to the track-shortened computed profile. Although other information about the aircraft’s flight path was available and the aircraft was not established on the ILS localiser, the captain used the glide slope deviation indicator as the primary vertical flight path guidance."

The first officer was engaged in a number of cockpit tasks, the approach looked normal to him until a visual check with the outside suggested the aircraft was too low. The first officer checked the primary flight display's vertical profile indicator which confirmed the aircraft was too low. In response to the first officer call "You are low" the captain switched to vertical speed mode adjusting the rate of descent to -500 feet per minute, but 8 seconds later the GPWS issued a "TERRAIN" warning, a second TERRAIN warning followed. The aircraft was at 1400 feet MSL, 600 feet AGL, about 9nm from touchdown and about 30 degrees off the final approach course, 1900 feet below the 3 degree glideslope and 100 feet below the lower limit of controlled airspace. The EGPWS issued "PULL UP" warnings.

Despite visual conditions the captain initiated a full EGPWS recovery procedure climbing to 4000 feet MSL. The aircraft subsequently positioned for an ILS approach to runway 16 and landed safely.

The ATSB analysed that the crew performance was consistent with degraded flight crew situation awareness. The ATSB analysed:

After accepting track shortening, the captain assessed that the aircraft was above the re-computed profile. As a result the captain selected open descent mode and half speed brake to increase the descent rate. This resulted in a higher than normal descent rate and, by continuing in open descent mode, the aircraft’s descent was only constrained by the altitude target selected in the flight control unit (FCU).

It was crucial, then, for the crew to maintain an increased awareness of the aircraft’s flight path relative to the computed profile and controlled airspace restrictions. However, it appears that the crew did not maintain that awareness because the aircraft subsequently descended significantly below profile until the EGPWS warnings at 1851.

Both pilots were expected to monitor the flight path and ensure that the trajectory and energy of the aircraft, current and projected, conformed to the planned approach. The first officer, as pilot not flying, reported monitoring the flight path during the approach. It is not clear if the first officer noticed that the aircraft was below profile during the latter stages of the approach but the captain, who was the pilot flying, was not advised that the aircraft was ‘low’ until just before the EGPWS warning.

The captain observed that the ILS glide slope indications were active and indicating that the aircraft was above the glide slope, which was consistent with his expectation. As a result, the captain considered the glide slope indications to be valid and useful for flight path guidance. Subsequently, the captain focussed on the glide slope without any apparent reference to the other available flight path or profile information.

Glide slope indications outside of the specified coverage area were unreliable and therefore an invalid source of flight path guidance. In addition, even if the signal was valid, following a glide slope indication with more track miles to fly than the straight-line distance to the glideslope antenna would, with reference to the track miles to run, result in a shallower flight path than the ominal 3° profile. Reference by the crew to the other available cues uring the visual approach would have increased the likelihood of them etecting that the aircraft was below profile.

When cleared for the visual approach, the captain set 1,000 ft in the CU, which although permitted by the manufacturer and operator, was well elow the altitude of about 2,200 ft required to intercept the final pproach path at a nominal 3° profile. Although the reason for the FCU etting by the captain could not be determined, the effect was that, in he open descent mode, the aircraft would descend to within 550 ft AGL nless the crew intervened. Selection of a more appropriate altitude arget would have provided an effective defence in the event of degraded ituation awareness.

Metars:
YMML 080900Z 22003KT CAVOK 28/17 Q1015 NOSIG
YMML 080830Z 17005KT CAVOK 29/17 Q1015 RMK 3AC100 5AC180 NOSIG
YMML 080800Z 17007KT CAVOK 30/16 Q1015 RMK 2CU080 6AC180 NOSIG
YMML 080730Z 18008KT CAVOK 30/15 Q1015 RMK 1CU080 6AC140 HZ NOSIG
YMML 080700Z 18010KT CAVOK 31/13 Q1015 RMK 2CU080 6AC135 HZ NOSIG
YMML 080630Z 17011KT CAVOK 31/15 Q1015 RMK 2CU080 6AC145 HZ NOSIG
YMML 080630Z 17011KT CAVOK 31/15 Q1015 RMK 2CU080 6AC145 HZ NOSIG
YMML 080600Z 18011KT CAVOK 31/16 Q1015 RMK 2CU070 3AC105 5CI260 HZ NOSIG
YMML 080530Z 18013KT CAVOK 32/16 Q1015 RMK 2CU070 3AC145 5CI260 HZ NOSIG
YMML 080500Z 16011KT CAVOK 34/17 Q1015 RMK 2CU070 3AC105 6CI260 HZ NOSIG
YMML 080430Z 16010KT CAVOK 33/17 Q1015 RMK 2CU070 3AC105 6CI260 HZ NOSIG
YMML 080400Z 15011KT CAVOK 34/17 Q1016 NOSIG
Incident Facts

Date of incident
Mar 8, 2013

Classification
Incident

Airline
Qantas

Flight number
QF-455

Aircraft Registration
VH-EBV

Aircraft Type
Airbus A330-200

ICAO Type Designator
A332

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