Investigation of San Francisco plane crash underway
Gabriel Black and James Brewer
11 July 2013
In a series of press conferences The National Transportation Safety Board (NTSB) has begun releasing details of its investigation into Asiana Airlines Flight 214, which crash landed at San Francisco International Airport (SFO) on Saturday, killing 2 and injuring 181 passengers. Such investigations normally take months before conclusions are reached, so the details that have been released have fueled considerable speculation in the media.
Also under scrutiny is the death of one of the two Chinese teenagers killed in the crash of the South Korean airliner. The San Francisco police are investigating whether firefighters ran over the injured girl, killing her. Her body shows signs of having been run over. Currently the coroner is completing an autopsy in order to deliver a final verdict on what happened.
One hundred and eighty people on board were admitted to the hospital. Two of the injured are unable to move their legs and many will undergo surgery on their spines. Geoffrey Manley, the head of neurosurgery at San Francisco General Hospital, told USA Today that several people have crushed vertebrae and many more have other forms of spinal injuries. These were apparently caused by passengers’ spines being shaken as the plane bounced before skidding to a halt.
According to the NTSB the aircraft, attempting to land on runway 28L during mid-day with clear skies, came in too slow. Voice recordings from the cockpit reveal that seven seconds before impact the pilots became aware that their speed was well below what was required of their aircraft. At that moment the pilots attempted to give the engines more power, but their attempt was unsuccessful. Without sufficient vertical movement a plane cannot be steered, nor can it remain in the air. If it does not have enough lift from its wings it will stall and fall to the ground.
Four seconds before impact, the aircraft’s computers shook the control sticks, alerting the pilots that the plane was indeed stalling. One second later, the plane was at its lowest speed in the descent—103 knots, or 118 mph. The engines were being pushed to go faster but the plane could not increase its speed to the desired 137 knots (157.7 mph). At the last second, the pilots tried aborting the landing. This, in conjunction with the last second thrust from the engines, caused the aircraft to tilt its nose upwards, making its tail low to the ground.
At impact, the plane was just meters from the San Francisco Bay. The tail smashed into the sea wall, breaking off the tail and tail cone. The crash landing also caused the landing gear to snap off. The plane skidded along on its belly, breaking off both engines. Near the end of its slide, it rotated on its nose, causing the cabin to momentarily be pushed back in the air as the craft pivoted. In amateur video the plane can be seen tilting upwards before impact, crashing, sliding, and then pivoting on its front-end before coming to a halt.
A fire that broke out upon impact caused the majority of damage. According to passenger accounts the evacuation proceeded quickly, save for two inflatable escape slides that expanded inside the cabin, nearly suffocating a flight attendant. Despite the growing flames, flight attendants remained in the aircraft until all the passengers had been evacuated. Some of the injured were carried out by fellow-passengers and flight crew.
The question arises: Why did the pilots not notice that they were well under the desired speed until seven seconds before impact? The following are some of the factors that may have contributed to the crash:
• The glide slope system on runway 28L, was inoperative. The system provides vertical guidance to keep a plane at the right elevation and angle during its approach. A notice on the Federal Aviation Authority’s web site reported that the system would be out of service from 1 June to 22 August due to construction.
• The auto-throttle control on the Boeing 777 was not functioning. The pilots had set the airspeed on the device to a proper landing approach speed of 137 knots, but it had fallen to 108 knots. The slow airspeed resulted in the aircraft’s approach being lower than its proper glide path (the approach trajectory necessary for a safe landing by a particular aircraft at a specific runway).
• The co-pilot, Lee Kang-guk, who was landing the aircraft, had only 43 hours of experience flying the Boeing 777, and was unfamiliar with landing at SFO airport.
• The pilot who was responsible to oversee the landing, though a veteran, was relatively new to the Boeing 777 as well.
Captain Chesley “Sully” Sullenberger, the veteran commercial pilot who executed the successful crash-landing on the Hudson River in 2009, spoke to the media about the lack of the Glide Path technology: “The pilots would have had to rely solely on visual cues to fly the proper glide path to the runway, and not have had available to them the electronic information that they typically have even in good weather at most major airports.
“What that means is that then the automatic warnings that would occur in the cockpit when you deviate below the desired electronic path wouldn’t have been available either. So we don't know yet if that’s a factor in this particular situation, but that’s certainly something they’ll be looking at.”
The pilots, four in total (split into two crews), were being interviewed Tuesday afternoon for the second time by officials. Until the interview process is complete, which is being done through translators, the pilots are not allowed to make any public statements.
The Airline Pilot Association, the world’s largest pilot union, criticized the investigation for having “already determined probable cause” and announcing details in piecemeal fashion before concluding the investigation. The association asked the investigation led by NTSB to “elaborate on factual material that has been excluded from public releases but must be considered in determining not only what happened, but why.” The NTSB responded by stating that “for the public to have confidence in the investigative process, transparency and accuracy are critical.”