Link SF34 at Sydney on Oct 24th 2022, too low of final ILS approach
Last Update: November 23, 2023 / 20:15:16 GMT/Zulu time
Incident Facts
Date of incident
Oct 24, 2022
Classification
Incident
Airline
Link Airways
Flight number
VA-669
Departure
Canberra, Australia
Destination
Sydney, Australia
Aircraft Registration
VH-VEQ
Aircraft Type
SAAB 340
ICAO Type Designator
SF34
Airport ICAO Code
YSSY
Australia's TSB rated the occurrence a serious incident regarding avionics/flight instruments and opened an investigation.
No NOTAMs regarding the ILS 34L were issued related to the occurrence. The NOTAMs however suggest that work on runway 34L was about to commence about 3 hours after the occurrence. Possibly related NOTAM:
H6083/22 NOTAMR H6059/22
Q) YMMM/QMTCM/IV/NBO/A/000/999/3357S15111E005
A) YSSY
B) 2210241200 C) 2210251900
D) DAILY 1200/1900
SUN-FRI 1200-1900
E) RWY 16R/34L 1738M NORTH END NOT AVBL DUE WIP
END RWY 34L 2224M FM RWY 34L START OF TKOF AND MARKED BY RED LGT
ALL TWY INT WITH RWY 16R/34L NORTH TWY B8 NOT AVBL
MEN AND EQPT ON NON-ACTIVE SECTION OF RWY NORTH OF TWY K INT
DECLARED DISTANCE AND GRADIENT CHANGES
RWY TORA TODA ASDA LDA
16R 2142 2232(2.37) 2172 -
34L - - - 2224
SUPPLEMENTARY TKOF DISTANCES
RWY16R- 2135(1.6) 2180(1.9) 2214(2.2)
START OF TKOF RWY 16R AT TWY B8
LDG RWY 34L LAST AVBL EXIT TWY B8
INT DEP FM TWY B8 REMAINING 2142M
RWY 16R HIGH INTST APCH LGT NOT AVBL
RCLL NOT AVBL
HIGH INTST RWY LGT NOT AVBL
LDG RWY 16R NOT AVBL
DEP RWY 34L NOT AVBL
REFER METHOD OF WORKS PLAN 21/002
On Nov 23rd 2023 the ATSB released an interim report summarizing the sequence of events:
On the evening of 24 October 2022 a Link Airways SAAB 340, registered VH-VEQ operated an air transport flight from Canberra, Australian Capital Territory to Sydney, New South Wales. The captain was acting as pilot flying, and the first officer as pilot monitoring. At 1944 local time, as the aircraft approached Sydney, air traffic control cleared the aircraft for the instrument landing system (ILS) approach to runway 34 left via the waypoint SOSIJ. This was the first ILS approach conducted in the aircraft on that day, with the captain acting as pilot flying.
Unknown to the crew, and prior to commencing the approach, a fault within the left (captain’s) display processor unit resulted in the captain’s electronic attitude director indicator (EADI) erroneously presenting a constant ‘on glideslope’ indication regardless of the aircraft’s altitude relative to the glideslope and without an EADI glideslope failure indication. Audio from the cockpit voice recorder and flight crew interviews indicated that the first officer’s EADI also probably presented similar erroneous information intermittently and without a failure indication.5 The EADI localiser6 course deviation and standby attitude direction indications were not affected.
As the aircraft approached SOSIJ in cloud, at night and with the autopilot engaged, the crew commenced a 90° left turn to intercept the localiser. The aircraft subsequently intercepted the localiser at an altitude and distance from the runway that positioned it close to being on the glideslope for the runway 34 ILS approach. The crew continued the approach using the autopilot and observed that the aircraft did not commence descending as expected to maintain the glidepath. In response, the captain disconnected the autopilot and manually increased the descent rate to that expected for the approach.
When the aircraft was about 5 nm from the runway, the crew conducted an altitude and distance check which showed that the aircraft was close to the glideslope. As the aircraft descended below 1,373 ft above mean sea level (AMSL) at 1,920 feet per minute, and with the erroneous ‘on-glideslope’ indication still present, the captain re-engaged the autopilot. The autopilot maintained this descent rate, resulting in the aircraft deviating significantly below the glideslope.
As the aircraft descended below 1,000 ft AMSL, the crew recognised that the approach was unstable due to the flaps not being in the required position. At about the same time, the ground proximity warning system activated to alert the crew to the glideslope deviation and, in response, the crew commenced a missed approach.
Following the missed approach, the crew carried out a required navigation performance approach to the runway and landed without further incident.
Metars:
YSSY 241100Z 05004KT 5000 -SHRA FEW008 BKN013 BKN033 18/17 Q1008=
YSSY 241056Z 06004KT 6000 -SHRA FEW008 BKN013 BKN018 18/17 Q1008=
YSSY 241030Z 07005KT 9999 -DZ FEW012 SCT018 BKN030 19/17 Q1008=
YSSY 240930Z 03007KT 9999 VCSH FEW011 SCT022 BKN050 19/17 Q1008=
YSSY 240900Z 04009KT 9999 FEW008 SCT020 BKN025 19/17 Q1008=
YSSY 240830Z 03009KT 9999 VCSH SCT008 BKN018 BKN022 19/17 Q1008=
YSSY 240818Z 04010KT 9999 VCSH SCT008 BKN018 20/18 Q1008=
YSSY 240800Z AUTO 04013KT 9999 // BKN008 OVC014 20/18 Q1008=
YSSY 240800Z AUTO 04013KT 9999 // BKN008 OVC014 20/18 Q1008=
YSSY 240730Z AUTO 06014KT 9999 // BKN012 OVC115 20/18 Q1007=
YSSY 240730Z AUTO 06014KT 9999 // BKN012 OVC115 20/18 Q1007=
YSSY 240700Z AUTO 02008KT 9999 // OVC115 20/18 Q1007=
YSSY 240630Z 04009KT 9999 FEW010 SCT025 BKN110 20/18 Q1007=
YSSY 240600Z 05011KT 9999 FEW010 SCT022 BKN027 20/18 Q1007=
Incident Facts
Date of incident
Oct 24, 2022
Classification
Incident
Airline
Link Airways
Flight number
VA-669
Departure
Canberra, Australia
Destination
Sydney, Australia
Aircraft Registration
VH-VEQ
Aircraft Type
SAAB 340
ICAO Type Designator
SF34
Airport ICAO Code
YSSY
This article is published under license from Avherald.com. © of text by Avherald.com.
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