Brief Description of the Occurrence
On the night of 31 October 2000, a Boeing 747-400 of Singapore Airlines Flight SQ006 was scheduled from Singapore Changi Airport to Los Angeles International Airport via Chiang Kai-shek International Airport (now Taiwan Taoyuan International Airport). The flight was uneventful from Singapore to Taiwan. However, the weather in Taipei was windy and rainy. The met department had also issued a warning of an incoming typhoon. After the layover, the flight was ready for departure. During the take-off run, the aircraft hit construction equipment parked on the runway. As a result, the aircraft could not continue its take-off roll and disintegrated into large portions. It also caught heavy fire due to fully refueled.
“When the right turn was the wrong turn”
Casualties and Fatalities
Out of the 179 passengers on board, 81 immediately lost their lives whereas, 98 survived the impact. Two of them later succumbed to their injuries. The pilot and Co-pilot also survived the accident.
Read more: Boeing Commercial Airplanes Division
The investigation of the accident was conducted by the Aviation Safety Council (ASC) of Taiwan following Annexure 13 of (International Civil Aviation Organization (ICAO) since the aircraft crashed in Taiwan.
Details of the Investigation
Events Prior to Taxiing out
Before the taxi, the Captain and Co-pilots had asked the ATC to use the longer Runway 05L rather than Runway 06, which was just on the opposite side of the passenger terminal. Singapore Airlines used to use the same runway. However, due to strong wind and heavy rain caused by an approaching typhoon, the aircraft couldn’t take off from Runway 06. Due to shorter length amidst such harsh weather conditions, the aircrew had opted for the Runway 05L, which was farther from the passenger terminal. Although not directly related to the accident, a fact later found during the investigation that the Captain had used Runway 05L more than two years ago.
Starting the Taxi
Data readouts from the FDR and CVR recovered from the burnt aircraft confirmed that the aircraft’s Captain failed to follow its correctly acknowledged ATC clearance along taxiway N1 and onto Runway 05L, a 60-meter wide instrument runway with Cat 2 signage, markings, and lighting. Instead, after turning right onto taxiway N1, at which point the aircraft should have continued straight ahead to reach the parallel Runway 05L (The runway declared for take-off), it turned prematurely to the right onto Runway 05R. (A temporarily closed 45-meter wide non-precision runway).
What Really Happened?
Although Runway 05R was mentioned in the NOTAM (Notice to Airmen) available to the crew advising that it was closed partway along its length with the initial section available for taxi use only, it was learned during the investigation that permanent conversion of Runway 05R to the status of a taxiway to be designated NC, was pending at the time of the accident and no change had been made to the runway status lighting. The later investigation also revealed no indications of its non-runway status readily available at the point on taxiway N1.
The Last Pin in the Coffin!
The aircraft is equipped with a Para Visual Display (PVD) [ an instrument that guides the pilot along the runway centreline during roll-out in poor visibility]. Primary Flight Display (PFD) [Electronic Flight Instrument System, is the pilot’s primary reference for flight information. However, most Primary Flight Displays are configured with a central attitude indicator on board. Upon entering the wrong runway 05 R, the flight crew did not check the Para Visual Display (PVD) and the Primary Flight Display (PFD). Both of these instruments must have indicated that the aircraft was lined up on the wrong runway. This was the last pin in the coffin.
Further to the investigations, it was also noted there was no taxiway centreline marking across the 05R threshold, only one leading onto the 05R runway centreline. This latter centreline was also much more clearly lit than continuing the unmarked taxiway centreline straight ahead towards runway 05L (The runway cleared for take-off).
The Ultimate Disaster
Due to the obscured visibility caused by the harsh weather, the flight crew did not see the construction equipment parked on the Wrong Runway 05R, just over a kilometer away from where the take-off roll began. By the time the pilot noticed the equipment, it was too late to swerve the plane away from speeding towards the obstruction as the aircraft’s nose had already left the ground. At 11.17 pm, about 33 s after the take-off roll started, the plane collided with the parked equipment.
The impact broke the plane into two parts and caused the filled fuel tanks to explode. The large fire that followed destroyed the forward section of the aircraft and the wings, killing many seated in the plane’s middle section. Many others suffered burns. The fire was eventually extinguished at 12.00 am.
The crash of SQ006 is the first and last fatal crash in the history of the Singapore Airlines till date.
There are multiple grey areas in this investigation.
- Like all the accidents, this occurrence also started with an event, and then the chain followed.
- Unavailability of a proper warning sign before entering the Runway 05R was the root cause of this occurrence. The reason being, despite all the other contributory factors, this particular factor particularly contributed to the accident. Similarly, the unavailability of taxi and runway lights also created confusion for the aircrew. Whatever lights were visible, they mistook it as the lights on Runway 05L (the runway cleared for taking off)
- Since the aircrew had not used the Runway 05L for quite a while, therefore, they were not too much acquainted with this runway. The Captain, in particular, had been using Runway 06 for the last two years.
- The second most critical factor attributable to this accident was the negligence of the pilot to overlook the displays at the PVD and PFDs. If they had given it due importance, they would have stopped and asked the ATC for clarity.
Read More: What is a NOTAM?
- The aircrew did not give importance to the issued NOTAMS first. Secondly, they should have asked ATC for any ambiguity in NOTAM before the departure.
- Although it was raining and a typhoon was approaching, therefore, a kind of stress was there on the minds of the aircrew. It generally happens otherwise. Departure gets canceled due to severe weather conditions. Generally, the pilots endeavor to avail themselves even the shortest weather window in case of bad weather. Although the aircrew later claimed that they were not in a hurry and had no stress for a quick departure.
- The ATC also did not keep a check on the departing flight and did not follow up as soon as they started taxiing.
- Due to heavy rain, the visibility was obscured. The ATC also failed to keep an eye on the aircraft through binoculars. Had it followed it visually, it would have stopped the aircraft as soon as the aircraft took the first turn to the wrong runway.
An Important Lesson Learnt
- Another important lesson learned in this investigation was about Crew Resource Management (CRM). The first officer did not challenge the Captain’s decision to overlook the PVD and PFD displays and continued the taxi.
The Taiwan Investigation Agency put the entire blame on the aircrew for its negligence in managing the entire situation. However, Singapore Airlines contested the investigation report and highlighted the deficiencies in the infrastructure, management of ATC, and airport authorities. The airlines blamed the Taiwan Airport authorities for their negligence in improper management of the airside.
The crash of Singapore Airlines Flight SQ 006 was miserable. It was a combination of human errors, loss of situational awareness, complacency, lack of crew resource management, infrastructure deficiencies, and communication. An aviation environment is very dynamic, and it demands complete focus and presence of mind. A simple slackness at any stage of flight operations can actually turn a normal situation into a worst one, like the one that happened in Flight SQ 006.