A Cessna 689 Citation Sovereign was operating an executive flight fromSan Fernando International Airport to the private Agropecuaria Río Juramento airstrip near Joaquín V. González. At Salta Airport a short stop was made before continuing to the final destination. Onboard a crew of two and 3 passengers.
The aircraft in its final position, some time after the mishap (Source and © JST)
At 12.15 local time, the aircraft lifted off from Salta Airport for the short flight to the private airstrip.
As the airstrip was not in the TAWS (Terrain Avoidance and Warning System) database the crew opted to silence the aural TAWS alarms to avoid nuisance warnings. This was not in accordance with the Airplane flight Manual, which gives the following operation limit for the TAWS;
"In order to avoid unwanted alerts, the Enhanced Modes (Terrain Awareness Alerting and Terrain Clearance Floor functions) must be inhibited by selecting TERR INHIB to ON when within 15 nm of landing at an airport for which any of the following conditions apply: a. The airport has no approved instrument approach procedure. b. The longest runway is less than 3500 feet in length. c. The airport/approach is not listed in Honeywell Avionics, Inc.
Document 060-4267-000, Revision A, or latest revision."
The aircraft on soft ground (Source; pbs.twimg.com © Unknown)
(TAWS compares the aircraft's position with a terrain database if an aircraft approaches an airfield that is not in the terrain database the TAWS system will give false alerts, for more information on TAWS click here)
During the final approach to runway 11, both the pilot were distracted by a flock of medium-size birds close to their path. Just before touchdown, the crew sensed that the aircraft was closer to the ground than normal, without the (normal) sensation of the wheels touching the runway. At the moment the fuselage struck the runway the captain (who was the pilot monitoring) realised the gear was not down, and quickly selected the gear down. However, there was not enough time for the gear to complete the down cycle. Without the gear down and locked, the aircraft settled on its belly and slid for 350 meters down the runway before drifting to the left of the runway and exiting the paved area of the runway and continuing on its belly for another 210 meters. Coming to a stop on soft ground on a heading of 340º on a perimeter wire. An evacuation was initiated and all occupants escaped without injury.
The aircraft as it came to a stop (Source; lagacetasalta.com.ar © Unknown)
The accident was investigated by the Argentinian Transportation Safety Board (JST Argentina). In their report (available by clicking here, please note the report is in Spanish) they concluded that the following factors played a role in the accident;
The cockpit speakers were muted before take0-off, leaving only audio available through the crew headsets.
All warning and terrain proximity warnings were muted
The crew removed their headsets during the final approach
The crew got distracted by the flock of birds
Checklists were not used
The landing gear was not extended