Amazon Sky AN26 near Lima on Dec 17th 2012, impacted Andes mountain

Last Update: September 7, 2013 / 17:13:30 GMT/Zulu time

Bookmark this article
Incident Facts

Date of incident
Dec 17, 2012

Classification
Crash

Aircraft Registration
OB-1887-P

Aircraft Type
Antonov An-26

ICAO Type Designator
AN26

Peru's Comision de Investigacion de Accidentes de Aviacion (CIAA) released their final report in Spanish concluding the probable cause of the crash was:

sudden shut down of both engines in cruise flight in adverse weather conditions due to incorrect use of the engines' anti ice systems.

Contributing factors were:

- poor flight planning with the flight crew not complying with routings authorized by company operations

- poor crew resource management failing to detect ice accretion and to engage the engine anti ice systems

- incomplete simulator training not providing specific lessons with respect to anti ice systems and specific lessons of landing with two engines inoperative

- departure for the flight although reported weather conditions at destination made a required visual landing impossible

- lack of procedures in the flight crew operating manual for the case of illumination of ICE indication

- lack of procedures in the flight crew operating manual for a restart of engine(s) in case of both engines having failed

- adverse weather conditions that caused ice to accumulate on the airframe and engines

The CIAA reported that the aircraft was flown by a captain (56, ATPL, 13,145 hours total, 12,308 hours on type), a first officer (33, CPL, 1,373 hours total, 1,193 hours on type), a flight engineer (38, FEL, 2,185 hours total, 2,130 hours on type) and a navigator (35, NavL, 657 hours total, 602 hours on type).

The aircraft had departed normally and was enroute at FL210 when the crew announced they were visually descending towards Malvinas Airport and cancelled their IFR flight plan. The air traffic controller inquired with the flight crew about their estimated time of arrival at Malvinas which was provided as 45 minutes later. This proved to be the last communication with the aircraft, which impacted terrain about 2 minutes after that communication.

A search found the wreckage of the aircraft the following day distributed over an area of about 2.5 square kilometers on Mount Huique, Tomas district, first ground contact at coordinates S12.1377 W75.7171 at 15,022 feet MSL.

The investigation determined that reported and forecast weather conditions at the estimated time of arrival indicated visibility of 10km or more, scattered cloud at 1200 feet and overcast cloud at 10,000 feet preventing a visual approach to the aerodrome. The alternate aerodrome at Pisco also reported overcast cloud at 6000 feet and thus was not available for a visual approach as needed.

The investigation reported that Peru's Servicio Nacional de Meteorología e Hidrología SENAMHI (National Service for Weather and Hydrology) could not provide any information. The investigation therefore referred to the overlay features provided by wunderground, that superimposes satellite images over Google Earth images, and entered the planned flight path (yellow), actual flight path (blue) and relevant waypoints (see image below).

The cockpit voice recorder and flight data recorder were recovered from the crash site and read out by the Interstate Aviation Committee (MAK) in Russia. Both recordings were good quality.

According to the cockpit voice recorder the flight crew requested cancellation of IFR flight plan and descent to FL195 to continue visually at 15:24Z, which was approved by the controller. Between 15:26Z and 15:29Z the ground proximity warning issues five "terrain" warnings, ATC terminates radar services at 15:29Z. The GPWS issues another terrain warning at 15:36Z, at 15:40Z the navigator reports the presence of ice. At 15:40Z, a few seconds after the navigator's comment about ice forming, ATC contacts the aircraft and inquires about the estimated time of arrival at Malvinas Airport, the crew provides an estimate of 16:27Z. Between 15:41Z and 15:42Z the sounds of activation of seven switches were recorded, at 15:41:23Z the engineer announced "engine failure", at 15:41:27Z the engineer announced "both engines failed", the first officer confirms "BOTH engines failed". The captain is heard to instruct to relight the engines, several switches are operated, the engineer announces "Yeah, relight", the captain instructs "aim for the valley, aim for the valley", the first officer exclaims "no, no engine relighted", the GPWS issues "TERRAIN! TERRAIN! PULL UP!" twice, at 15:42:26 sounds of first impact are recorded.

The flight data recorder contained at least two flights including the accident flight and confirms that both engines ran down simultaneously coinciding with the engineers exclamation that both engines had failed.

The CIAA analyzed that the crew continued on runway heading for about 30nm after departure taking the aircraft south of the Lima aerodrome along the coast before the aircraft turned left, a route that was not contained in the company's approved route manual for the flight to Malvinas, which required the aircraft basically to turn east after departure.

After the aircraft turned east the commander commented that the ridges were covered in cloud, the first officer annotated that the clouds would reach up to FL350. 3-4 minutes later the commander requested the cancellation of IFR with Lima control.

There is no evidence that during the climb before and after the turn to east the aircraft's anti-ice systems had been activated.

After the crew had cancelled IFR and had descended to FL195 the aircraft descended gradually indicative of the formation of ice and degradation of flight performance, the navigator detected the presence of ice. The crew subsequently went on to activate the anti-ice systems, during that process both engines stopped, both propellers went into their feathered positions. The crew attempted to relight engine #2 (right hand), which succeeded a few seconds prior to first impact, the engine failed again on impact, the aircraft bounced off before impacting ground a second time.

Following the failure of both engines the crew rolled the aircraft right to about 30 degrees of bank to aim for the valley instead of continuing slightly left for the possible escape path ahead, the escape path via Cockaine however was partially obscured by clouds. This maneouver reduced the altitude and shortened the time available to relight the engines.

The CIAA analyzed that the operation of the anti ice systems is essential when operating in level flight with cloud formations present leading to accretion of ice and the activation of according ice warning lights in the cockpit.

The CIAA analyzed that there was no evidence of load distribution, aircraft gross weight, fuel, navigational aids, air traffic control performance or malfunction of other aircraft systems contributed to the accident. In particular the CIAA analyzed that the failure of both engines was not the result of any system malfunction but the result of ice accretion in the engine inlets. There is evidence however, that engine #2 was in the process to run up and the propeller was about to exit the feathered position at the time of first impact.

The remains of the aircraft (Photo: CIAA):


Overview of crash site (Photo: CIAA):


Impact sequence (Photo: CIAA):


Superimposed satellite image and flight path (Graphics: CIAA/wunderground):
Incident Facts

Date of incident
Dec 17, 2012

Classification
Crash

Aircraft Registration
OB-1887-P

Aircraft Type
Antonov An-26

ICAO Type Designator
AN26

This article is published under license from Avherald.com. © of text by Avherald.com.
Article source

You can read 2 more free articles without a subscription.

Subscribe now and continue reading without any limits!

Are you a subscriber? Login
Subscribe

Read unlimited articles and receive our daily update briefing. Gain better insights into what is happening in commercial aviation safety.

Send tip

Support AeroInside by sending a small tip amount.

Newest articles

Subscribe today

Are you researching aviation incidents? Get access to AeroInside Insights, unlimited read access and receive the daily newsletter.

Pick your plan and subscribe

Partner

ELITE Logo

ELITE Simulation Solutions is a leading global provider of Flight Simulation Training Devices, IFR training software as well as flight controls and related services. Find out more.

SafetyScan Pro

SafetyScan Pro provides streamlined access to thousands of aviation accident reports. Tailored for your safety management efforts. Book your demo today

AeroInside Blog
Popular aircraft
Airbus A320
Boeing 737-800
Boeing 737-800 MAX
Popular airlines
American Airlines
United
Delta
Air Canada
Lufthansa
British Airways