Procedures related event - Melbourne Airport, Victoria, on 4 November 2007, HS-TJW, Boeing 777-2D7

On 4 November 2007, a Boeing Company 777-2D7 (777) aircraft, registered HS-TJW, was being operated on a scheduled passenger service from Bangkok, Thailand to Melbourne, Vic. with 17 crew and 277 passengers on board. During the conduct of a non-directional beacon (NDB) non-precision approach to runway 16 at Melbourne, the crew descended the aircraft below a segment minimum safe altitude. Soon after, the crew received two enhanced ground proximity warning system cautions. At that time, the crew became visual with the ground below and the Melbourne aerodrome controller observed the aircraft 'unusually low for an aircraft'. The crew levelled the aircraft and made a visual approach and landed, on runway 16.

The investigation found that the aircraft had descended below a critical altitude whilst carrying out an NDB approach and that the crew did not monitor the aircraft's progress correctly during the NDB approach.

The aircraft operator had known about the difficulties in flying approaches without constant angle approach paths and was in the process of training flight crews on procedures specific to NDB approaches when the incident occurred. In October 2007, the operator introduced a training program to instruct pilots on a new method to conduct those approaches. At the time of the incident, the pilots of the 777 had not undergone that training.