On September 26, 1997, Garuda Indonesia Flight 152 was operating a scheduled domestic service from Jakarta to Medan using an Airbus A300B4-220 registered PK-GAI.
The aircraft carried 222 passengers and 12 crew members. As it approached Medan’s Polonia Airport, the weather was poor, with reduced visibility and mountainous terrain surrounding the airport.
The flight was being radar-vectored for an ILS approach to Runway 05. Controllers initially instructed the crew to turn left to heading 240 degrees and later to heading 215 degrees.
At about 1:30 p.m., Flight 152 was cleared to descend to 2,000 feet and was instructed to turn right to heading 046 degrees to intercept the runway localizer.
A critical chain of confusion then developed. Another aircraft, Merpati Nusantara Flight 152, had been handled by the same controller earlier. The controller initially addressed Garuda Flight 152 using the wrong call sign, causing the crew to disregard the transmission.
When the correct call sign was used, parts of the previous instruction were repeated, but important information concerning the side of the airport from which the approach was to be made was not clearly communicated.
Believing the aircraft was expected to approach from the opposite side, the captain began turning left instead of right. The first officer eventually noticed the mistake and questioned the captain.
The controller confirmed that the aircraft should turn right, creating further confusion as the crew attempted to establish the correct heading.
While the cockpit crew concentrated on the heading problem, the aircraft continued descending. The crew failed to maintain the assigned 2,000-foot altitude and the Airbus descended toward high terrain.
The radar system’s relatively slow update rate also contributed to the controller having an inaccurate picture of the aircraft’s position and movement.
At approximately 1:32 p.m., Flight 152 struck trees and mountainous terrain near Buah Nabar, about 27 kilometres from the runway threshold. The aircraft impacted at approximately 1,550 feet above sea level and was destroyed. All 234 people aboard were killed. There were no survivors.
The subsequent investigation concluded that the accident was a controlled flight into terrain caused by a combination of flight crew and air traffic control errors. The investigation found that confusion over the direction of the turn reduced the crew’s awareness of their altitude while they were focused on resolving the lateral-navigation problem.
Investigators also identified weaknesses in pilot conversion training between the Airbus A300B4-FFCC and A300-600 variants, whose cockpit instrumentation differed significantly. The report also highlighted inadequate vectoring charts used by controllers and the failure of the aircraft’s ground-proximity warning system for undetermined reasons.
The crash exposed how several relatively small communication, navigation, training and equipment issues could combine within minutes to produce a catastrophic outcome. The loss of Flight 152 became a major lesson in cockpit situational awareness, clear ATC communication and the importance of preventing controlled flight into terrain.
