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ASN Wikibase Occurrence # 244268
Last updated: 13 October 2021
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Time:08:32 LT
Type:Silhouette image of generic C56X model; specific model in this crash may look slightly different
Cessna 560XL Citation XLS+
Owner/operator:Würth Aviation GmbH
Registration: D-CBEN
MSN: 560-6089
Fatalities:Fatalities: 0 / Occupants: 5
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:6 km W of St. Gallen-Altenrhein -   Switzerland
Phase: Approach
Departure airport:Schwäbisch Hall-Hessental Airport (EDTY)
Destination airport:St. Gallen-Altenrhein Airport (ACH/LSZR)
Investigating agency: STSB Switzerland
On March 12, 2019, a Cessna Citation XLS+ business aircraft with registration mark D-CBEN took off at 07:10 UTC for a commercial instrument flight from Schwäbisch-Hall (EDTY) to St. Gallen-Altenrhein (LSZR). On board were two crew members and three passengers. On the same day, at 07:26:00 UTC, the pilot of the helicopter Robinson R44 II with the registration mark HB-ZWN requested clearance for a local visual flight from the air traffic controller of St. Gallen-Altenrhein airfield. The controller gave the pilot of HB-ZWN clearance for take-off and departure via waypoint Victor at 07:26:22 UTC in English with the condition to stay south of the extended runway axis of runway 10, as an aircraft was on an IFR approach to runway 10.
Since the helicopter pilot did not understand the instruction, the controller repeated it in German. At 07:30:28 UTC the crew of D-CBEN reported to the air traffic controller with the information that they were aligned on the localizer line and on the glide path of the ILS of runway 10. The traffic information concerning the helicopter HB-ZWN and that it would remain south of the runway axis was then received from the ATCO.
Meanwhile the pilot of HB-ZWN followed the shore line of Lake Constance towards waypoint Victor and approached more and more the stand line of the landing course transmitter. At 07:31:52 UTC the crew of D-CBEN reported that they saw the helicopter in its 2 o'clock position. The crew of D-CBEN received the TCAS warning "traffic, traffic" at about 4 NM before landing, with a yellow symbol in a 2 o'clock position about 200 ft lower and discovered the helicopter shortly thereafter. At 07:32:00 UTC the TCAS Resolution Advisory (RA) "descend" command was given, whereupon the Pilot Flying (PF) immediately initiated a manual descent and the Pilot Monitoring (PM) informed the controller of the TCAS alarm. A few seconds later, the TCAS command to increase descent rate ("increase descent") was given, which the PF immediately followed. The crew saw the helicopter at an acute angle to the rear right at an estimated distance of about 200 m. The two aircraft crossed at 07:32:07 UTC at a distance of 0.1 NM (185 m) with an altitude difference of 225 ft (68 m), with the helicopter slightly above the approaching Citation. The crossing took place at about 3.5 NM (about 6 km) from runway threshold 10 to about 2900 ft AMSL. At 07:32:11 UTC the TCAS evasion order ended. This was immediately followed by the "terrain, terrain" warning of the Enhanced Ground Proximity Warning System (EGPWS), whereupon PF again cut the ILS glide path from below. Afterwards the HB-ZWN flew on to the excursion point Victor, while the D-CBEN landed uneventfully on runway 10 of St. Gallen-Altenrhein.
As the controller later stated, he had followed the departure of HB-ZWN first visually, then on his screen (Tower Air Situation Display - TASD). In German, he informed the HB-ZWN pilot that he had not followed his instructions and that an Air Traffic Incident Report (ATIR) would be generated. The helicopter pilot, however, was of the opinion that he was south of the runway axis. As he later stated, he had had the aircraft in sight for some time. At that time he was not aware that the departure route to waypoint Victor along the shore would cross the runway axis above the village of Horn. Likewise, it was only after the dangerous approach that he realized that in such a case it was permissible to deviate from the standard route. The volume of traffic was low.

The serious incident, in which a helicopter pilot departing under visual flight rules crossed the flight path of a business aircraft flying under instrument flight rules, was caused by the helicopter pilot not following the air traffic controller's instructions and the latter's failure to monitor the helicopter's flight path sufficiently. The low flight experience as well as an inadequate flight preparation of the helicopter pilot contributed to the occurrence of the serious incident.



Accident investigation:
Investigating agency: STSB Switzerland
Status: Investigation completed
Duration: 1 year and 7 months
Download report: Final report


Photo of D-CBEN courtesy

Shannon (EINN / SNN)
14 May 2021; (c) Derek Gaynor

Revision history:

21-Oct-2020 12:21 harro Added

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