Darwin SB20 at Billund on Dec 10th 2015, descended below minimum safe height
Last Update: January 3, 2019 / 23:01:05 GMT/Zulu time
On Dec 23rd 2015 Switzerland's SUST reported, that the occurrence was rated a serious incident, the SUST have opened an investigation.
On Mar 9th 2016 the Danish Havarikommissionen (HCL) released their statement announcing that the investigation was delegated to the Swiss SUST. The aircraft had been on an ILS approach to runway 27 when the crew observed glideslope fluctuations prompting them to go around. The crew subsequently positioned for a non-precision localizer approach to runway 27 in daylight and instrument meteorological conditions but descended below the minimum safe procedure altitude causing the GPWS to issue warnings. The crew went around and diverted.
On Jan 3rd 2019 the SUST released their final report concluding the probable causes of the serious incident were:
The serious incident emerged from the aircraft’s descent below the stipulated minimum altitude for a non-precision approach. Therefore, a safe altitude above the obstacles was no longer guaranteed.
The crew’s poor monitoring of the vertical flight path has been identified as the direct cause of the incident.
The following factors have been identified as directly contributing to the serious incident:
- Deficient approach planning with regards to the vertical flight path.
- Reduced performance of the pilot flying, probably due to tiredness.
The approach chart, which had no distance/altitude table and thereby impeded the monitoring of the approach, systematically contributed to the serious incident.
Although it did not influence the development and course of the serious incident, the following risk factor was identified during the investigation:
- The procedure following a warning from the enhanced ground proximity
warning system (EGPWS) was not consistently applied.
The aircraft had performed an ILS approach to Billund's runway 27 but noticed problems with the glideslope indication at about 800 feet AGL, the glideslope indication fluctuated between 2 dots "fly up" and 1 dot "fly down", and about 250 feet below the minimum altitude at that position and initiated a go-around. With the glideslope indication problem the crew decided to perform a LOC approach, however, descended too steeply and continued to descend below the MDA. The excessive descent triggered a GPWS warning, the crew initiated another go around and returned to Berlin.
The SUST analysed that the ILS transmitters at Billund operated normally, low visibility approach procedures were not in use. The cause of the glideslope problem could thus not be determined, "interference to the glideslope and locator signals can occur if vehicles or aircraft are located in the protected areas."
During the following LOC approach the SUST analysed: "The commander delegated the task of monitoring the vertical profile to the PM and concentrated exclusively on piloting. However, the PM was not able to do this and did not communicate that fact. Therefore, the two crew members did not notice the deviation from the stipulated vertical profile in good time. The tasks of the PF include monitoring the lateral and vertical navigation, and should therefore not be left entirely to the PM. Every member of an aircrew is obliged to speak out if an allocated task cannot be fulfilled. However, in this investigated incident the PM failed to inform the commander that he was unable to monitor the vertical profile."
The SUST analysed that the captain initiated the go around just before the EGPWS sounded the warning, however, did not adopt the EGPWS escape procedure which ensures maximum climb performance. The maximum climb performance might have been necessary however in a scenario like this.
EKBI 101650Z AUTO 24015KT 210V270 9000NDV -RA OVC009/// 08/07 Q1017 RERA
EKBI 101620Z AUTO 23014KT 200V260 6000NDV RA OVC005/// 08/07 Q1017
EKBI 101550Z AUTO 22014G25KT 8000NDV -RA OVC007/// 08/08 Q1017 RERA
EKBI 101520Z AUTO 22016KT 6000NDV RA OVC005/// 08/08 Q1017
EKBI 101450Z AUTO 22016G26KT 4900NDV +DZ OVC005/// 09/08 Q1017
EKBI 101420Z AUTO 22017G27KT 2800NDV -SHRA BR OVC005/// 08/08 Q1017
EKBI 101350Z AUTO 22018G31KT 3300NDV -SHRA BR OVC006/// 08/08 Q1018
EKBI 101320Z AUTO 22018G30KT 2700NDV DZ BR OVC006/// 08/08 Q1018
EKBI 101250Z AUTO 22019G33KT 190V250 3800NDV DZ BR OVC006/// 08/08 Q1018
EKBI 101220Z AUTO 21020G33KT 2700NDV -RA BR OVC007/// 08/08 Q1018
EKBI 101150Z AUTO 22021G34KT 2900NDV -DZ BR OVC006/// 08/08 Q1019
EKBI 101120Z AUTO 22019G34KT 190V260 2900NDV -DZ BR OVC008/// 08/08 Q1019
EKBI 101050Z AUTO 22020KT 6000NDV OVC010/// 09/07 Q1019
EKBI 101020Z AUTO 22019G31KT 190V250 9000NDV OVC009/// 09/07 Q1019
Aircraft Registration Data
This article is published under license from Avherald.com. © of text by Avherald.com.
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