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Accident description
Last updated: 20 November 2017
Status:Final
Date:Friday 10 October 1997
Time:22:10
Type:Silhouette image of generic DC93 model; specific model in this crash may look slightly different
McDonnell Douglas DC-9-32
Operator:Austral Lineas Aéreas
Registration: LV-WEG
C/n / msn: 47446/561
First flight: 1969
Total airframe hrs:56854
Cycles:54800
Engines: 2 Pratt & Whitney JT8D-7B
Crew:Fatalities: 5 / Occupants: 5
Passengers:Fatalities: 69 / Occupants: 69
Total:Fatalities: 74 / Occupants: 74
Airplane damage: Destroyed
Airplane fate: Written off (damaged beyond repair)
Location:21 km (13.1 mls) E of Nuevo Berlin (   Uruguay)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Posadas Airport, MI (PSS/SARP), Argentina
Destination airport:Buenos Aires-Jorge Newbery Airport, BA (AEP/SABE), Argentina
Flightnumber:AU2553
Narrative:
Austral flight AU2553 took off from Posadas, Argentina at 21:18 for a domestic flight to Buenos Aires-Aeroparque. Before departure there was no specific warning for weather conditions to be encountered during the flight.
En route at FL350 the aircraft encountered bad weather with Cumulonimbus clouds (reportedly topping at 49000 feet), an outside air temperature of -59°C and windshear conditions with winds at 80 km/h.
The aircraft deviated from the airway and entered the Montevideo Flight Information Region (FIR) without contacting the Montevideo controller.
At 22:04 the aircraft entered an area with icing conditions. Three minutes later the first officer, who was pilot flying, initiated a descent without prior permission. Meanwhile the captain contacted Ezeiza Control, requesting permission to descend. Ezeiza Control radioed that the flight was over Uruguay territory and that they needed to contact Montevideo Control for permission.
During the descent the first officer complained that his airspeed indicator did not seem to be working correctly.
Descending through FL300, the first officer extended the slats. The pilots were trained to extend slats when recovering from approach to stall situations at 10-12 000 feet. However, the actual airspeed at the time of extension was higher than permitted. This exceeded the design limit, causing an asymmetry. The pilots lost control of the plane which then entered an uncontrolled descent, crashing in a swampland on the banks of the Uruguay River. The wreckage was found at 04:40 the next morning in a 25 feet deep, 80 feet wide crater.
Anomalous airspeed indications preceded the slat extension (a sudden increase from 200 knots to 450 knots IAS in 4 seconds), possibly due to icing of the pitot tubes.

Probable Cause:

PROBABLE CAUSES: (translated from original Spanish report)
IMMEDIATE CAUSE: "The Accident Investigation Committee Aviation of the Republic of Uruguay, determined that the immediate cause of the accident was likely that at a pressure altitude of 30,000 ft, the first officer, who was in charge of the controls, found himself in a flight condition which induced him to extend the slats.
He did this at a speed much higher than the limit of the structural design of the slats and by extension damage occurred, causing an asymmetry, with consequent loss of control fro which he was unable to recover.
The co-pilot's interpretation as to the need to extend the slats would have been a result of erroneous indications of low speed (IAS), caused by blockage of the pitot tubes which resulted from atmospheric icing.
It was not possible to determine if the obstruction was caused by the crew by not activating the heating system via the selector switch, or failure of that system.
CONTRIBUTING CAUSES:
a) No indication of Mach No. on the speed indicators installed in the accident aircraft within its flight envelope, with air speeds below 250 KIAS.
b) Lack of training of the pilots in flight instrument failures and upset recovery.
c) Lack of training of the pilots in the recovery of approach to stall in the DC-9 aircraft in "clean configuration" in accordance with the procedures specified in the FCOM, section 5, 10-0-0, code 30.
d) Lack of instruction and pilot training in crew resource management (CRM).
e) Absence of a warning light PITOT/STALL-HEATER OFF on the annunciator panel of the aircraft.
f) Deficiency in procedures for operational flight dispatch.

Accident investigation:
cover
Investigating agency: DINACIA Uruguay
Status: Investigation completed
Duration: 1 year and 2 months
Accident number: Final report
Download report: Final report

Classification:
Thunderstorm

Loss of control

Sources:
» Aviation Week & Space Technology 03.11.1997 (41)
» Aviation Week & Space Technology 20 October 1997 (65)
» ICAO Adrep


Follow-up / safety actions

DINACIA Uruguay issued 24 Safety Recommendations

Show all AD's and Safety Recommendations

Photos

photo of McDonnell Douglas DC-9-32 LV-WEG
FDR readout of last 90 seconds
photo of McDonnell Douglas DC-9-32 LV-WEG
The monument remembering the victims of the crash of Austral flight 2553.
photo of McDonnell Douglas DC-9-32 LV-WEG
Add your photo of this accident or aircraft
 

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Posadas Airport, MI to Buenos Aires-Jorge Newbery Airport, BA as the crow flies is 828 km (518 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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