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ASN Wikibase Occurrence # 207794
Last updated: 2 December 2021
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Date:19-FEB-1994
Time:12:30
Type:Silhouette image of generic P68 model; specific model in this crash may look slightly different
Partenavia Costruzioni Aeronautiche S.p.A P.68B
Owner/operator:
Registration: VH-PNS
MSN: 71
Fatalities:Fatalities: 0 / Occupants:
Other fatalities:0
Aircraft damage: Substantial
Location:8km W of Carnarvon, WA -   Australia
Phase: Unknown
Nature:Training
Departure airport:Carnarvon, WA
Destination airport:Carnarvon, WA
Investigating agency: BASI
Narrative:
The aircraft was involved in Civil Search and Rescue Unit training at the time of the occurrence and the trainee dropmaster was undertaking his first live dispatch of a twin raft training pack under the supervision of an instructor. The aircraft was being flown at 120 knots and 200 feet above sea level for the exercise. The drop proceeded normally until the first raft pack was dispatched after which the trainee retained his grip on the second raft pack beyond the point in time when the second pack should have been dispatched. As the rope reached full length a tug was felt and shortly afterwards the first raft pack entered the water placing a much greater load on the rope causing the second raft pack to be pulled from the trainee's grip. It struck the rear door frame before exiting the aircraft, causing substantial damage.

Raft packs connected by 440 m of rope are normally dispatched from the aircraft at six second intervals allowing the rope to be pulled completely from special containers attached to each raft pack. The raft packs are normally located one on top of each other and protrude through the door. They are pushed outwards and downwards by the dispatcher to ensure they remain clear of the aircraft. The dropmaster may also use an alternative procedure by waiting until he feels a tug on the rope before dispatching the second raft. During training, raft packs made from a solid wooden cylinder and webbing are used in lieu of rubber rafts. The training pack has less elasticity than the actual pack. When an actual raft is dropped it begins to inflate during its descent and will not generally contact the water before the second raft is released. However, a training raft pack does not inflate and therefore it falls at a faster rate, entering the water sooner than an actual raft. On this flight the early entry into the water of the training pack led to the uncontrolled release of the second raft and the subsequent damage to the aircraft. The twin raft deployment system does not include a weak/frangible link to protect the aircraft from damage resulting from such circumstances.

The trainee dropmaster had been trained and subsequently briefed for a single raft drop. On the day of the occurrence the aircraft to be used for the single raft training became unserviceable and the exercise was re-scheduled for a twin raft drop. He had not been trained or briefed for the twin drop until immediately prior to departure. Before each flight the crew normally received a briefing from the pilot-in-command on the procedures and calls to be used during the drop. During the preflight briefing by the pilot-in-command, it became evident that the trainee dropmaster was not familiar with the twin raft drop procedures. The briefing was discontinued to allow the the trainee dropmaster to be given instruction on twin raft drops by the dropmaster instructor. The preflight briefing was subsequently resumed but the dropmaster instructor did not attend this briefing as he had become occupied with other duties. The trainee did not carry out any dummy runs to practise the twin raft drop procedures. During the flight the dropmaster instructor introduced procedures that had not been explained during the preflight briefing. In addition, the intercom between the dropmaster and pilot failed and hand signals (a normal alternative procedure) were used. Additionally, the clock, used for timing the drop sequence, was stopped during the live drop run causing the dropmaster to lose his timing reference.

Sources:

https://www.atsb.gov.au/publications/investigation_reports/1994/aair/199400431/
https://www.atsb.gov.au/media/4933620/199400431.pdf

Accident investigation:
cover
  
Investigating agency: BASI
Status: Investigation completed
Duration:
Download report: Final report


Images:

Photo of VH-PNS courtesy AirHistory.net


Carnarvon (YCAR / CVQ)
16 April 1977; (c) Geoff Goodall (via David Carter)

Revision history:

Date/timeContributorUpdates
18-Mar-2018 07:14 Pineapple Added

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