RUSHING TO DIE:
The crash of Singapore Airlines Flight 006
[A Singapore Airlines 747-400 crashed during takeoff, from Taiwan on October 31, 2000, with the loss of 82 lives.]
Now that it is clear that the tragic crash of SQ flight 006 at Taipei airport was caused by the captain’s attempting to takeoff on a runway that was closed, dark and under construction, the question is:
How could he have made such an egregious error?
My immediate answer is: A severe case of tunnel vision.
Tunnel vision is a phrase pilots and accident investigators have used for many years to describe a pilot’s mental state, which apparently focuses on a single goal or outcome with such intensity, that other important information is blocked out of the mental process. Such blocked-out information can sometimes be crucial to a safe operation, as this accident proves once again.
While we will have to wait for the findings and conclusions of the official accident report, to fully appreciate all factors that contributed to such a fatal error, it is already apparent why tunnel vision might have occurred.
All airliners have safety crosswind limits for both takeoff and landings. The eye of Typhoon Xangsane was moving toward the Taipei airport and producing winds up to 90 mph. The reported winds and visibility at the airport were still below the plane’s safety limits, when it pushed back from the gate. But, as time elapsed, the winds were bound to increase as the eye of the storm moved closer.
The captain knew the longer it took them to taxi out and takeoff, the more likely it was that those winds might reach or exceed the airplane’s safety limits. If that happened before he commenced the takeoff roll, he would be forced to return to the gate. If he did that, it would be many hours before they would be able to safely depart Taiwan. It probably would have required passengers and crew to go to hotels for many hours because the legal duty times of the flight crew would be exceeded. All that would cost Singapore Airlines a lot of money and would probably produce hostility among many passengers who deemed it imperative to arrive at their destination on time.
Thoughts like that were likely paramount in the captain’s mind and the key to why he failed to see the “red flags” all around him as he moved from the gate to the takeoff roll.
(1) Taxi chart warning:
The TPE airport pilot information chart has the cryptic warning, for pilots encountering limited visibility conditions, as did the pilots of SQ 006:
(2) Runway Lighting System:
The correct runway (05L), had high intensity white lights (HIRL) marking both edges of that runway and also white centerline lights, turned on for the full length. Both those edge and centerline lights were required for takeoff and landings after dark and, additionally, because of the very limited visibility. And, the touchdown zone lights (TDZ) would also be visible, to any pilot lining up on runway 05L for takeoff.
The wrong runway (05R), where SQ 006 crashed, should have had only green centerline lights turned on, indicating to all pilots it was being used solely as a taxiway, not a runway. The white edge lights, should not have been turned on, and there were no TDZ lights. Investigators are attempting to determine if the tower had turned on the white runway edge lights for runway 05R. If tower personnel had made the mistake of turning on those white edge lights, then that would be considered a contributing factor in reinforcing the captain's belief that he was lined up on runway 05L. However, NBC news interviewed one lady who survived the crash without significant injury. She stated she enjoyed night takeoffs because she loved to watch the runway edge lights speed by as the takeoff roll accelerated. But, she didn't see any such lights this time; it was dark as she looked out her window while the plane raced down the runway, prior to impact.
(3) Approach Lighting System (ALS):
Since the active runway (05L), was in use for both landing and departing aircraft, the approach lighting system for that runway would have been visible (it's very bright and can penetrate fog) to the captain of SQ 006, out his left cockpit window as he made a right turn onto what he thought was runway 05L. But, he would not have seen any ALS lights, for the runway he selected, because none was installed on the approach to runway 05R. That runway can be used only for landings in visual conditions and only with special permission (usually for smaller aircraft).
(4) Runway Number Designations:
Both runways were properly marked with very large white numbers painted on the surface at the end. SQ Flight 006 had to taxi over the numbers that read “05R” to begin its fatal takeoff roll. Those numbers could be clearly read by the pilots as they were illuminated with the taxi headlights on that 747-400. [But, see question "e" below in REVISIONS section.]
The flight papers, that provided all the necessary information to plan and conduct that flight, included the notification to airmen that runway 05R was closed for construction work and that only a portion of it could be used for taxi purposes. The captain planned for and knew that he was required to use runway 05L for takeoff. [However, see REVISIONS section below]
Yet, with all those red flags, all three pilots in that cockpit failed to recognize that the plane was lined up to takeoff on 05R, instead of the planned and required runway, 05L.
The captain was highly experienced and had been through the Taipei airport many times before. It is a very common operation, at Taipei, for planes to push back from the gate and then to taxi down runway 23L/05R, on their way for takeoff on runway 05L. It is likely those pilots had done so numerous times before. When that procedure is followed, the plane makes a right turn off of the end of 23L, at taxiway N1, and then stops short of 05L until cleared to taxi onto 05L. Most importantly, when that common taxi procedure is followed (using 23L as a taxiway, as opposed to using it as a runway), the plane does not have to cross any other runway before arriving at runway 05L.
But if, after pushing back from the gate, they taxied down the NP taxiway (sometimes called the "ramp" taxiway), instead of down runway 23L, and if the minds' of the captain and the two first officers were highly preoccupied with the deteriorating weather while also calculating the crosswind component -- to determine if the wind was still below the safety crosswind limit of that 747-400 -- then they might have mentally reverted to the habit pattern of taxiing down 23L. If so, then they subconsciously expected to turn right off that taxiway and then make another immediate right turn into the takeoff position on runway 05L. In other words, their common previous experience, at the Taipei Airport, might have overruled their awareness that they were following a different taxi route than normal and that they had to first cross runway 05R, before they would be in position to turn right onto runway 05L.
All pilots carry information charts for all the airports they fly to, in loose leaf binder form, so they can constantly be revised whenever important information changes. The last revision of the two basic information pages, for the Taipei Airport, was dated April 28th, 2000. It is on the second page of that revision, in the "Departure" paragraph # 5, that the cryptic warning to "exercise extreme caution" [see RED FLAGS (1) section above] is found. That page still advises pilots that 23L/05R can be used for either purpose: a runway (for takeoffs) or for a ground taxi route between an active runway and the terminals.
However, the Runway/Airport layout chart (two more pages), was revised on October 27, 2000, just 4 days before the crash. The change in information that generated that revision? It was:
"CHANGES: Runway 05R/23L redesignated."
According to this new chart, in apparent conflict with the basic information pages, there is no longer a runway designated 05R/23L. Since October 27th, it was designated as taxiway NC.
The second page, of that revision, shows the types of runway lighting for any given runway. Prior to that revision, runway 05R was shown as having only runway edge lights ("RL" -- the acronym for standard runway edge lights). After that Oct. 27th, revision, the column for 05R is missing -- no lights listed at all -- since it is no longer a runway.
a) Did the pilots of SQ 006 have that Oct. 27th revision in their possession?
b) Had they read and understood that change?
c) Did that revision affect the wording of the Notams, in the pilot's flight planning papers, about a portion of 23L/05R being closed for construction?
d) If they had read it, did it somehow mislead them to think there would only be one possible taxi route so as to expect themselves to be at runway 05L immediately after the expected right turn at the end of the taxi route?
e) Had the airport authorities removed the large white painted sign on the end of the old runway 05R, or could the pilots still see "05R" as they taxied into position for takeoff?
f) If they actually did taxi down the NP ("ramp") taxiway, did the tower clear them to cross runway 05R, or did it make any reference to 05R at all? Did the tower, because of that new revision, omit that kind of clearance, that would have been normal and expected ("cleared to cross 05 R"), prior to that new revision? Did this new revision provide necessary safety information to the pilots, or did it simply add to the information overload that surrounding circumstances were already imposing?
One could pose endless questions like these; it is certain accident investigators will be asking many more in this area of inquiry.
Early news reports seemed to imply the plane should never have left the gate because the weather was so bad. But, as is so often the case, news reports are designed to make gains in market share, not to ascertain relevant facts. When severely distraught relatives, leap to quick conclusions (quite understandably) about why they have suffered such a terrible loss, the press, like a pack of swirling vultures, swoops in for the feast. Time and time again they displayed scenes of grief being expressed as rage against Singapore Airlines for attempting to fly in such bad weather.
But neither visibility nor wind was the cause of that crash. There is no reason to infer the captain or Singapore Airlines was negligent in allowing the plane to proceed to takeoff in such weather conditions. While the visibility was low, it was over 900 meters (approximately 2,900 ft.) and that is almost 3 times the required visibility for landing, which is far more hazardous than taking off. The first concrete barrier struck by that 747-400 as it nosed upward, grasping desperately for altitude, was about 1,400 meters (approximately 4,500 ft.) from the starting end of that closed runway. The strong headwind was the only reason the plane was able to exceed the takeoff V1 (maximum abort) speed, prior to first impact. Had the headwind component been a steady 20 kts. stronger, they probably would have cleared all obstructions and there would have been no accident.
Since the runway was 05 (because the magnetic heading was actually 053 degrees), and the wind was reported by the tower as "020 [degrees] at 28, gusts to 50 [knots]," as the takeoff clearance was given to SQ 006, then the headwind component was 15 to 45 kts. and the crosswind component was 13 to 25 kts.
Pilots carry a wind component chart to determine if the crosswind is reaching or exceeding the maximum demonstrated safety limit of the airplane. That is probably why it took the captain a full minute to actually start the takeoff roll, after the tower gave him that takeoff clearance: they were diligently plotting the tower's reported wind on their component chart to ensure it was still below the crosswind safety limit of 30 kts. And, that is probably the most important ingredient in the witch's brew which created their severe case of tunnel vision. They were so intent on being certain the winds were within the maximum safety limits, that they somehow lost track of where the plane really was on the ground. They "saw," not reality, but what they expected to see, what their past experience told them to see. They weren't actually aware of the route they had taken to get from the gate to the takeoff position, for they would have known they were on the end of 05R, if they had been cognizant of the plane's position at all times.
Tunnel vision is a form of distraction -- a very severe form. It has been causal in many previous accidents. Part Two, of this editorial will recount past tunnel vision accidents.
November 12, 2000
Robert J. Boser
The Editor of this Web Page, now retired, was an airline pilot for
33 years and holds 6 specific Captain's type-ratings on Boeing Jet Airliners,
including the Boeing 747-400.