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30 July 2013

FAA suggests non-US airline crews lack basic piloting skills

On Sunday 28 July 2013, the FAA issued a recommendation that non-US airlines landing at San Francisco International airport (SFO) use their GPS systems to help guide them during landings operated under visual flight conditions at the airport's longest runways, including runway 28L, which was the one being used by the Asiana 777 that crashed at SFO on 6 July 2013 . This implies that non-US pilots may not have the basic piloting skills needed to consistently land aircraft at SFO under visual flight rules.

Dr. Todd Curtis on new FAA recommendations

An FAA representative stated that the recommendation was a response to concerns that some non-US airline pilots may not have sufficient experience or expertise to land an airliner using visual approach procedures, which don't rely primarily on electronic landing aids.

Neither the FAA or the NTSB has stated that the visual approach procedures were a factor in the crash of Asiana flight 214 on July 6th. However, since that crash, the FAA has revealed that an unspecified number of flights involving Asiana, EVA Air, and other non-US carriers have had more aborted landing attempts than usual at SFO.

Since last week, the FAA has instituted a different landing protocol for visual approaches on runway 28L, the intended landing runway for Asiana flight 214, and the parallel runway 28R. That protocol will have air traffic controllers at SFO requesting that non-US airliners use a GPS-based navigation system to assist those flight crews in landing on either of those runways.

In a visual approach, pilots typically don't rely on a variety of electronic aids like an instrument landing system to align the aircraft with the runway and to keep to the aircraft on the proper glide slope. On runway 28L, the glide slope system was not operable on the day of the accident, and is scheduled to be out of commission until 22 August 2013. During a visual approach, pilots may use the glide slope system, as well as other systems like the precision approach path indicator (PAPI) system, which was used by the crew on Asiana fight 214.

While the FAA did not state when the recommendation for non-US airlines would be lifted, it would likely not be necessary once the glide slope system is back in operation.

Additional information

26 July 2013

Disturbing implications of the recent 787 fire in London

The recent 787 fire at Heathrow Airport in London appeared at first to be a relatively minor event with a limited impact beyond the aircraft involved. However, when the investigative authority, the Air Accidents Investigation Branch (AAIB) of the UK, released its preliminary report on the event, the recommendations that were made implied that the problem had the potential to be far more serious had it occurred in flight.

Key findings of the AAIB report
The initial AAIB report, stated that the fire damage coincided with the location of the emergency locator transmitter (ELT), and although the AAIB did not state that the ELT was the source of the fire, the aircraft was unpowered at the time of the fire, and no other aircraft systems in the area contained an energy source capable of starting a fire. The ELT is designed to operate without any power from the aircraft's electrical system, and is powered by a set of chemical batteries using a Lithium-Manganese Dioxide (LiMnO2) composition. This kind of battery represents a different technology from the lithium-ion batteries associated with the fires on two different 787 aircraft in January 2013.

What the fire fighters encountered in London
According to the AAIB, when fire fighters entered the aircraft through the front left door (the 787 has four pairs of doors), they encountered thick smoke and had to open at least two other cabin doors to clear the smoke. They were unable to extinguish the fire with a handheld Halon fire extinguisher, and had to forcibly remove a ceiling panel and use water from a fire hose to put out the fire. While this was apparently not an complicated procedure for the fire crews on the ground, it could have been an entirely different situation had this occurred in the air.

Visible external damage to 787 in London

Why a fire in flight would have been much more dangerous
The AAIB investigation is ongoing, and the organization has not identified the ELT as the source of the fire. However, if the ELT turns out to be the source of this particular fire, it raises the very disturbing possibility that this kind of fire could have occurred not just on the ground in an empty aircraft, but also while the aircraft was in the air. This could potentially be a far more serious event in the air for the following reasons:

  • Unlike on the ground, opening one or more doors to evacuate smoke is not an option in flight,
  • While there are handheld fire extinguishers in the cabin that flight attendants can use in an emergency, equipment or other tools suitable for removing ceiling panels are not typically available to cabin crew.
  • While the fire fighters in the London incident had access to water hoses to put out the fire, no such option would be available to an airborne 787.
  • in the event of an onboard fire, typical emergency procedures include landing at the closest suitable airport, but since the 787 often flies on routes that are an hour or more from a suitable airport, passengers and crew could be exposed to large amounts of smoke and fumes for a significant amount of time.
  • Emergency oxygen systems may not have been useful for passengers since these systems are typically designed to supply supplemental oxygen, in other words, passenger would be breathing a combination of oxygen from the emergency oxygen system and ambient air from the cabin, including any smoke or fumes that are present in the cabin.

A nightmare scenario
Simply put, the aforementioned conditions imply that had this event occurred in the middle of a flight, the cabin crew may have been unable to reach the source of the fire, and even if they did, they may not have been able to put the fire out. The aircraft involved in the fire at London's Heathrow airport sustained damage to the composite structure of that airplane's fuselage. Conceivably, if the fire had been allowed to burn for a significant amount of time, a situation that could have occurred had the airplane been inflight, the fire could have led to significant damage to the aircraft's systems, or could have caused the aircraft to lose its structural integrity. Either outcome could have led to the loss of the aircraft and all on board.

An additional twist to this story
While the previous scenario may be disturbing to the average passenger, what may cause additional concerns, especially to aircraft manufacturers and airline operators, is the possible role of the ELT in the fire in London. This is a system that is noteworthy for not being a source problems that could lead to the loss of an airliner. In fact, according to the AAIB, the manufacturer of the ELT involved in the London fire, Honeywell, has produced some 6,000 ELT units of the design used in the Ethiopian 787 involved in the London fire event, and that event is the first incident where the ELT system generated a significant level of heat.

Actions taken to deal with the threat
Following the recommendations of the AAIB, the FAA and other regulatory agencies around the world have ordered that 787 ELTs be deactivated, inspected, or removed. Until the AAIB, Boeing, and Honeywell figure out the role played by the ELT in the London fire, questions will remain as to whether the 787 ELT represents an unexpected and potentially fatal risk to 787 passengers.

25 July 2013

Key safety and technology trends affecting airline passengers

The last few weeks has seen the world media pay a tremendous amount of attention airline safety issues, especially in the wake of the fatal crash landing of Asiana flight 214 in San Francisco on 6 July 2013 and the landing incident on 22 July 2013 involving a Southwest Airlines 737 in New York. These two events have actually highlighted several of the key safety trends in aviation that will likely affect passengers not only in the US, but around the world.

How the crash of an Asiana 777 demonstrated improvements in aircraft
This accident represented not only the first fatal accident involving the 777, but the first fatal accident involving a large jet airliner in the US in almost 12 years. Perhaps more significant was that an accident that resulted in significant damage to the aircraft and a post-crash fire resulted in only three fatalities.

777 accident in San Francisco

While luck plays a part in any fatal accident with survivors, perhaps a more significant role was played by improvements in aircraft design and crew procedures that have occurred over the last few decades, including the following:

  • Aircraft designs that minimize the risk of rupturing fuel tanks when landing gear are sheared away,
  • Cabin materials that are designed to be both more fire resistant and less prone to give off dangerous fumes if they do catch fire,
  • Passenger seats that are designed to withstand greater crash forces,
  • Crew training that emphasizes coordination of cabin crew and flight crew actions during emergencies, and
  • Stricter requirements for passenger evacuation to allow the evacuation of a full aircraft in 90 seconds or less, even if half of the exits are not useable.

How safe is flying?
Since the beginning of large scale airline operations, and especially in the last 30 years, the risks of flying, specifically the risk of a fatal event that kills passengers, has steadily decreased, and the likelihood of survival increasing, in part through innovations in technology and procedures. These improvements are happening because of deliberate efforts by the aviation community and the governments that regulate aviation to identify risks and find ways to eliminate them, make them less likely to occur, or lessen the effects of unwanted outcomes like plane crashes.

Working on the important risks
Aircraft manufacturers, international aviation organizations, and government regulators regularly share information on where the major problems are and what steps have to be taken to address them. The two recent accidents in the US, both of which are being investigated by the NTSB, will be part of this sharing process. They were both landing related accidents, which happens to be a area of high interest among airline manufacturers, airlines, and regulatory authorities.

The findings of the investigation, as well as any recommended changes to technology or procedures, will be provided not only to the organizations involved in the accidents, but to the general public, and will likely contribute to future changes to airline industry, changes that will make these kinds of accidents less likely.

How technology puts power in the hands of the people
The recent accidents in San Francisco and New York were also examples of how technology in the hands of passengers and the public has radically changed the relationship the public has with the airlines. In both cases, news of the accidents, including photos and videos, went out not only through traditional news media, but also through Twitter, YouTube, Vine, and other social media applications. In the case of the crash in San Francisco, the NTSB used Twitter and YouTube to put photos, press conferences, and other information from the investigation online, allowing any interested person to get the information direct from the source, without waiting for traditional media to filter the content.

737 landing accident at LaGuardia

Other key technology trends
The growth in the availability of affordable and portable online access continues to be a reality in virtually all areas of the globe. While it is impossible to say where that technology is going, it is clear that there are several areas where this technology has made a huge difference to airline passengers compared to ten or even five years ago:

  • Allow for easy ticket price comparisons and ticket purchases online,
  • Provide personalized in-flight entertainment,
  • Provide passengers with the means to document accidents, incidents, and poor airline customer service, and to share it with the world, and
  • Allow passengers to access a full range of information about an airline 24 hours a day.

Perhaps the greatest change for passengers is that the existence of the Internet makes the entire aviation system much more transparent to everyone. When accidents occur, the news flashes around the world in seconds. It has become very difficult for an airline, aircraft manufacturer, or government agency to hide the truth about their activities from the public, either because someone publishes a photo or other information that reveals the truth, or because information such as accident and incident data that used to be very difficult for the public to find is now much easier to find.

This last point may not be important to airline passengers who live in countries with a free and open press where critical reporting on the activities of governments and corporations in the norm. In many parts of the world, especially countries where there has been a rapid increase in the standard of living and much greater access to air travel services, having the ability to find information from sources that are not controlled by their government, especially information about airlines that are often partly or completely controlled by their government, would be next to impossible without access to the Internet.

24 July 2013

NTSB launches investigation of Southwest Airlines LaGuardia accident

22 July 2013;Southwest Airlines 737-700; flight 345; LaGuardia Airport, New York, NY: The airliner, with 145 passengers and five crew members on board, was on a scheduled flight from Nashville, TN to New York, had a problem after landing which led to a collapsed nose landing gear and a runway excursion.

After the aircraft came to a stop in a grassy area adjacent to the runway, the occupants evacuated the aircraft using the emergency slides. Nine of the occupants were treated for minor injuries, and no one was serious injured or killed.

The NTSB has launched a formal investigation of this accident, and has already begun processing the information from the cockpit voice recorder and flight data recorder. While this is not a major investigation on the scale of what is happening with Asiana flight 214, this will be a more extensive investigation than what would normally happen after a typical landing gear accident. This is likely because of the level of damage caused by this event.

As can be seen in the photo below, the nose landing gear not only collapsed, it was also pushed up into the electronics bay beneath the cockpit.

Why so much media attention to this accident? While the response of the NTSB is typical for this kind of accident, the media response is not. While it did not garner the kind of nonstop coverage that happened on major cable news shows after the Asiana crash, it has two qualities that are often associated with high levels of media coverage of airline events:

  • It involved a major US airline, and
  • It occurred in New York, the most influential media market in the US, and arguably in the the entire English-speaking world.

The last point is possibly the most important since not only do many US news and broadcast media organizations have headquarters in New York, many of the people who work at those organizations use the airport where the accident occurred. Had the same event occurred at a US airport that was not in a major media market, it is unlikely that this event would have led to much media coverage.

Additional resources
Previous Southwest events

Photo: NTSB; Video: Bobby Abtahi

18 July 2013

AAIB releases bulletin on 787 fire plus additional 777 crash interviews

On 18 July 2013, the UK's Air Accidents Investigation Branch (AAIB) released a special bulletin related to the 12 July 2013 fire on an Ethiopian Airlines 787 at London's Heathrow airport. The AAIB made two safety recommendations, the first was to advise the FAA to initiate action to have 787 operators deactivate the emergency locator transmitter (ELT), and the second was to have the FAA conduct a safety review of the installation of ELTs in other aircraft where the ELTs are also powered by lithium batteries.

While the AAIB does not have any authority to implement these recommendations, it is very likely that the FAA, Boeing, and all of the 787 operators will respond relatively quickly to the recommendations.

AAIB summary of the fire
The AAIB special bulletin contained the following key information about the events leading up to the fire:

  • The Ethiopian Airlines 787 landed at Heathrow at 0527 hours on 12 July 2013 after an uneventful flight, with no technical problems reported by the crew.

  • After it was towed to a parking area, external power was turned off, and the aircraft was left unpowered.

  • An employee in the air traffic control tower noticed smoke coming from the aircraft at 1534 hours, and fire fighters arrived about one minute later.

  • After a fire crew entered the aircraft, they observed indications of fire above the ceiling panels, and had to move a ceiling panel in order to put out the fire.

  • A later examination revealed extensive heat damage in the rear fuselage in the crown area, just to the left of the centerline, an area which coincided with the location of the ELT.

  • The ELT, which was powered by a set of chemical batteries containing a Lithium-Manganese Dioxide composition, was the only aircraft system in that area that had the potential to initiate a fire when the aircraft was unpowered.

About emergency locator transmitters
ELTs are battery-powered radio transmitters that are carried aboard airliners, other civil aircraft, and most military aircraft. Thay are designed to survive most accidents, and to transmit a signal that can be used by rescue crews and even satellite-based monitors to locate a crash site. The FAA requires the use of ELTs on commercial airliners.

According to the AAIB, the manufacturer of the ELT associated with the recent 787 fire (Honeywell) has produced about 6,000 ELTs for use in a wide range of aircraft, and this the first time the manufacturer has what the AAIB calls a 'thermal event.'

The ELTs used by Boeing in the 787 are all made by Honeywell, and they are powered by a set of five non-rechargeable batteries, each of which is roughly the size of a common household "D" cell battery.

What's next for the 787
There are currently 68 787 aircraft flying with 13 operators around the world. Although the FAA has not made a formal request for airlines to implement the AAIB recommendations, it is likely that Boeing and the airlines will take action relatively quickly. If the recommended actions are taken, in the short term 787s may be flying without ELTs.

While flying without ELTs may make it harder to find an aircraft that has an emergency in an unpopulated area, the FAA can allow airliners to fly for short periods of time without a working ELT, so implementing these AAIB recommendations will likely not cause the FAA to ground the 787. Other regulatory bodies around the world typically follow the actions of the FAA in situations such as this one.

Media interviews with Dr. Todd Curtis about the Asiana 777 crash
The following three interviews with Dr. Curtis were made in the days immediately following the crash of Asiana flight 214

- WGN radio - The Dean Richards show on 8 July 2013
- Bloomberg television interview 8 July 2013

CCTV America 8 July 2013

Additional information

17 July 2013

Update on 787 fire in London plus radio interview on 777 crash

Update on the 12 July 2013 787 fire in London
On 12 July 2013, an Ethiopian Airlines 787 caught fire while parked on an apron at London's Heathrow Airport. There were no passengers on the aircraft at the time of the fire, and no one was injured or killed.

The initial witness and physical evidence shows that this event resulted in smoke throughout the fuselage and extensive heat damage in the upper portion of the rear fuselage. The photo below shows that the fire burned through the top of the fuselage in the rear of the aircraft between the two rear doors and near the base of the vertical fin.

(click to enlarge)

The British Air Accidents Investigation Branch (AAIB) is investigating the fire, and has not yet released any statement about the likely causes of the fire. However, several things are known about the investigation:

  • The aircraft had arrived from Addis Ababa, Ethiopia about nine hours before the fire was discovered.

  • In addition to the AAIB, participants in the investigation include the FAA, NTSB, the Civil Aviation Authority of Ethiopia, Boeing, Ethiopian Airlines, and Honeywell International.

  • Honeywell is the manufacturer of the emergency locator transmitter (ELT) used in the 787.

  • The battery in the ELT is based on a lithium manganese-dioxide technology and not on the lithium-ion technology associated with the batteries that caught fire on two different 787 aircraft in January 2013.

  • The fire was in the rear of the fuselage, and was remote from the areas of the aircraft containing the main battery and the auxiliary power unit batteries, the batteries associated with the grounding of the entire 787 fleet earlier this year.

Dr. Todd Curtis interviewed by eFM radio in South Korea
In the following July 15, 2013 interview on the South Korean eFM radio show Prime Time with Henry Shinn, Dr. Todd Curtis discussed several issues associated with the ongoing investigation into the July 6, 2013 crash of an Asiana 777 in San Francisco, CA, including speculation about the cause of the crash, the role of automated systems in the cockpit, and the NTSB investigative process. Many of the issues raised in this interview included questions about the 777 crash answered in a previous article.

Additional information

15 July 2013

Questions about the crash of Asiana flight 214

Over the past week, numerous questions and comments about the Asiana plane crash have been sent to Dr. Todd Curtis at Below are answers to some of the more popular questions posed by the public and the news media.

According to international protocol, who will be in charge of the investigation?

According to section five of Annex 13 to the Convention on International Civil Aviation, the state of occurrence of the accident (in this case, the United States) is required to begin an investigation, and has the option of delegating the investigation to another state or to a regional organization. Typically in the US, the NTSB leads airline accident investigations, unless it is determined to be caused by a criminal act. If that is the case, the FBI takes the lead in the investigation. So far, there is no indication that there was a criminal act, so the NTSB will likely lead and complete the investigation.

How long until this investigation is completed?

Typically, an NTSB investigation takes over a year to complete. The NTSB has published 13 reports on aircraft accidents that have occurred since the beginning of 2009. The shortest time until completion was just over nine months, and the longest was just under 27 months.

The information presented so far by the NTSB seems to point to either a case of pilot error or mechanical failure. From what you have seen, is there any way that you can say which one is more probable?

It is too early to focus on any one possible cause since the NTSB is still in the early part of the investigation, and has only processed and released some of the factual data from the investigation. It is also possible that the probable cause (or probable causes) may include something besides pilot error or mechanical failure. As the investigation continues, the NTSB will know more about the causes of the accident.

While Asiana Airlines stated that the pilot who was in control during the landing was an experienced airline pilot, his limited experience with the 777 seems to lend weight to the pilot error argument. What is the appropriate length of time for a pilot to be trained?

That question is beyond my expertise, but I will say that standards for airline pilots are extremely high around the world, and part of that high standard includes extensive training when airline pilots transition to new aircraft. That training includes ground school to familiarize pilots with systems and procedures, as well as training in high-fidelity aircraft simulators, including full motion simulators, that simulate the sights, sounds, and sensations pilots would experience in an actual aircraft. These training programs have often been developed in concert with the manufacturer to ensure that the training reflects the behavior of the aircraft.

The South Korean government as well as the world's largest organization of airline pilots, the nternational Federation of Air Line Pilot's Association, criticized the NTSB for revealing too much from the Asiana flight 214 investigation. What do you think about the press conferences held by the NTSB since the accident?

The press conferences have been an excellent source of information about the investigation. In my opinion, the kind of information the NTSB has provided is similar to what has been provided from past accidents. The biggest differences between this investigation and prior major investigations have been the access provided to the public and the NTSB's use of social media to inform the public of the availability of recorded press conferences, photographs, and other information from the investigation. In short, the NTSB is providing information much more quickly, and in a more accessible manner than before, but the kind of information being released is consistent with what has been released in the past.

The 777 is reportedly one of Boeing's flagship products and has a strong safety record. Why do you think this is the case?

There are many reasons for this record, and one of them are the high certification requirements of the FAA. At the time of its development, the 777 incorporated regulatory requirements of the FAA, and of the equivalent organizations in Europe and elsewhere. One of those requirements was the inclusion of 16G passenger seats.

A 16G seat is one that is tested in ways that simulate the loads that could be expected in a survivable accident. These seats must withstand two different accident scenarios, one in which the forces are mostly in the vertical or downward direction, and one in which the forces are predominantly in the forward or longitudinal direction. The highest load factor these seats must withstand is in the forward direction at 16Gs (16 times the force of gravity). It is unclear what kinds of forces were experienced by the seats on flight 214, but the NTSB will determine that as part of the investigation.

All aircraft certified by the FAA after 1988 had to have these seats, and since the 777 was certified after 1988, every 777 was delivered with these kinds of seats. The previous FAA standard for commercial airliners was 9G seats.

There are several other regulatory requirements and industry innovations that were incorporated into the 777, and I will mention just a few:

  • Cabin materials that are more fire resistant and less likely to produce dangerous fumes when burned,
  • Evacuation requirements that include emergency lighting on or near the cabin floor so that they can be more easily seen in a smoke-filled cabin.
  • Ground proximity warning systems to help warn pilots when they are flying too low or flying in an area of rising terrain,
  • Collision avoidance systems that warn pilots when other airliners are on a collision course or about to pass at an unsafe distance,
  • Emergency exit systems that allow a 777 with a full load of passengers to evacuate all passengers in 90 seconds or less while using only half of the eight available exits,
  • Multiply redundant aircraft systems, including a flight control system that will allow differential engine thrust to be used if flight control surfaces are not working,
  • Main landing gear that are designed to break off in a hard or crash landing in such a way that the wing fuel tanks are not punctured, and
  • Communications systems, including radios to communicate with airport personnel and cabin public address systems, that will continue to operate after a crash even if electrical power is no longer available from the engines or auxiliary power unit.

As an aviation safety expert, what do you think made this crash so survivable?

Very likely several of the items mentioned in the previous answer helped to keep the number of fatalities low, particularly the use of fire resistant cabin materials, the design of the emergency evacuation systems, the design of the main landing gear, the availability of aircraft communications systems, and the presence of the emergency exit lighting on or near the floor. Another factor was the prompt response from emergency and medical personnel who were at and near the airport.

According to the NTSB, the pilots ordered the passengers to remain seated for 90 seconds after the plane came to a halt, until the cabin crew noticed a fire when the evacuation was initiated. Were 90 seconds too long?

The decision to evacuate an aircraft after a crash is made by the crew based on the conditions inside and outside the aircraft. According to the NTSB, the crew made the decision to evacuate when fire was seen outside the cabin. The NTSB will review the accident to determine if there were any problems or errors in the timing of the evacuation decision or the execution of the evacuation.

According to international protocol, how are accident victims usually compensated?

Compensation for events involving international flights is covered by the Montreal Convention, and damage sustained by a passenger or a passenger's baggage in the event of an accident is not subject to any financial limit. How the compensation happens can be complex, especially since the accident took place in the United States. Because of the location of the accident, there may be a variety of international, federal, and state of California laws that may be relevant. Typically, the parties involved agree to a settlement without having a trial, and the terms of the settlement are not shared with the public.

Who is responsible for paying for the claims of victims?

Usually, any private company, government organization, or private individual that has some or all of the legal responsibility for the accident may have to pay victim claims. While many different entities may be legally responsible, in the US, typically only private companies end up paying compensation to victims or their families.

Does the NTSB determine who is legally responsible for paying for the claims of victims?

The NTSB investigation is separate from the process for determining legal liability. While the NTSB investigation is typically completed in about a year, legal proceedings involving victim compensation may take much, much longer to complete.

There remains substantial data from Boeing and the airline that must be reviewed. What do you think is the focal point of this ongoing investigation?

I currently don't have an opinion about what the focus will be because the investigation is still in the early stages. The focus of the NTSB investigation is to determine the probable cause or probable causes that led directly to the accident, as well as to identify those contributing causes that indirectly led to the accident. As the NTSB stated in several of their briefings last week, there is still a substantial amount of information that has to be gathered and analyzed before they will be able narrow the focus of the investigation.

As far as safety is concerned, what long-lasting influence will this accident have in the aviation field?

The long term effects will largely be determined by the recommendations that come out of the NTSB investigation, and any additional insights that the industry may gain from this accident. Until the investigation is complete, it is very difficult to predict the long-term influences of this accident.

Additional information 13 July 2013 summarizing the two prior NTSB press conferences 10 July 2013 article on the role of the autothrottle 8 July 2013 article on early findings of the crash investigation
Other Asiana plane crashes
Other 777 plane crashes
Accident details from Aviation Safety Network
Wikipedia page on this accident

The day after the crash, Dr. Curtis of and Capt. Tom Bunn of the SOAR fear of flying program, who both spent several hours on the day of the crash on cable news programs providing expert commentary, discussed the media's response to the accident and shared their thoughts on the early reports of the crash.

13 July 2013

Summary of final two NTSB briefings on Asiana 777 plane crash in San Francisco

On Wednesday, 10 July 2013 and Thursday, 11 July 2013, NTSB conducted their final two press conferences in San Francisco, and covered a variety of issues around the accident, including the operation of the autopilot and autothrottle, damage to the airplane, injuries to the flight attendants, the evacuation of the aircraft, and other initial factual findings from the investigation.

The NTSB emphasized in both of these press conferences that the information was factual in nature, and in many cases had not yet been confirmed or corroborated. For example, statements received from the flight crew still have to be matched up with information from sources such as the cockpit voice recorder (CVR) and the flight data recorder (FDR).

Cockpit automation and its role in the crash
As mentioned in a previous article, use of the autothrottle by the crew to maintain speed was an issue because although the crew was heard on the CVR stating that the target speed was 137 knots, the aircraft was significantly slower than that speed before the crash. In Wednesday's press conference, the NTSB stated that there were five distinct autothrottle modes used in flight, and in the last 2.5 minutes of flight, there were several autothrottle and autopilot modes used.

As explained by the NTSB, the autopilot helps pilots manage pitch, roll, attitude, and heading; while the autothrottle helps to control speed or thrust. The two systems can work together, and the NTSB has to determine, with the help of Boeing, the following:

  • Whether autopilot and autothrottle modes were commanded by the pilots or activated inadvertently,
  • How the various autopilot and autothrottle modes are designed to work, and
  • What are the ways the systems are expected to respond in the various modes.

Comparison to automobile cruise control
NTSB chair Deborah Hersman used an analogy to a much simpler automated system to illustrate the role that an autothrottle plays. Like in an airliner, a car's cruise control can be set to a specific speed, but it is up to the driver to monitor the speed. Also, cruise control may not engage if the car is in a particular mode, for example below a certain speed. While in cruise control, the driver may be allowed to increase or decrease speed within certain limits. Disengaging cruise control can be done by disarming the system or by hitting the car's brake.

Status of the pilots on flight 214
There were a total of four pilots on board, and they consisted of two crews. The first crew consisted of a training captain going through his initial operating experience (IOE) on the 777 and an instructor pilot (IP) who was a training captain. The relief crew consisted of a captain and a first officer (FO) This first crew performed the takeoff from Seoul and flew for several hours before the relief crew took over, and then the first crew flew approximately the last 1.5 hours of the flight.

Shortly before landing, when the aircraft was at around 10,000 feet, the relief FO entered the cockpit and was in the jumpseat for the rest of the flight. The NTSB provided details on the experience of the three pilots in the cockpit:

  • The training captain was in the left seat at was the pilot flying (PF),
  • The training captain had about 9,700 total hours, including about 5,000 as pilot in command (PIC),
  • The PF was hired by Asiana in 1994, and trained in Florida,
  • The PF was rated to fly the 737, A320, 747, and 777, and from 2005-2013 flew the A320, serving as an A320 captain before moving to the 777,
  • The PF was also a ground school and simulator instructor for the A320 and A321
  • The IP was also a 777 captain who served in the South Korean air force for about 10 years before joining Asiana,
  • The PF's IOE was to consist of 60 flight hours and 20 flight legs, and had gone through 10 flight legs and about 35 flight hours at the time of the crash,
  • The IP had about 13,000 flight hours, including about 3,000 in the 777, and 10,000 as a PIC,
  • The IP served as the PIC on flight 214, and was sitting in the right seat,
  • This flight was the first time that the PF and the PIC had flown together, and it was the PIC's first trip as an instructor pilot
  • The relief FO was a former F-5 and F-16 pilot in the South Korean air force, and had about 4,600 total hours, including 900-1,000 hours in the 777,
  • The relief FO had flown to San Francisco five or six times as an observer.

Landing aids in use at the airport
Air traffic control was allowing pilots to operate under visual flight rules (VFR) when flight 214 was approaching the San Francisco airport (SFO), which means that pilots were not required to use the instrument landing systems at the landing runway (28L) or any automated systems on their aircraft. One of the electronic aids that provide aircraft guidance on their glide slope was inoperable, but this had been published for some time and all flight crews using the airport should have been able to see this information. The NTSB has not stated if this crew were aware of this.

A glide slope aid that was in operation at runway 28L were the precision approach path indicator (PAPI) lights, a set of four lights arranged in a horizontal line that provide pilots with a visual indicator of whether the aircraft on the glide slope, above the glide slope, or below the glide slope.

A pilot who is on the glide slope would see two sets of red lights on the left and two sets of white lights on the right. In the example shown here (not from SFO), the three left indicators are red and the right one is white, indicating that the aircraft is slightly below the glide slope. Four red lights would indicate that the aircraft is well beloe the glides slope, and four white lights is an indicator of being well above the glide slope.

Final approach sequence
Over the last two press conferences, the NTSB discussed the following key parts of the final approach:

  • The approach path took the aircraft directly over SFO, followed by a wide teardrop left turn to line up with the runway (see below),

    (click to enlarge)
  • Air traffic control (ATC) called for a maximum airspeed of 180 knots until the aircraft was five miles out,
  • The IP recalled that the aircraft was above the intended glide path at 4,000 feet, and that vertical speed mode was set at 1,500 feet per minute,
  • ATC gave a landing clearance about 1.5 miles from the runway, about 90 seconds prior to the crash,
  • There was a sink rate callout prior to the aircraft reaching 500 feet,
  • At about 500 feet, the FP noted a blinding flash of light directly in front of the aircraft but not on the runway,
  • The FP stated that he looked away into the cockpit, and was able see the cockpit instruments, including the speed tape,
  • There was no mention of the light on the CVR,
  • The FP believes it may have been a sun reflection, and the NTSB is determining if this could have been the case,
  • There was an automated 500 foot callout about 35 seconds before the crash,
  • Shortly after this callout, the landing checklist was completed,
  • At about 34 seconds prior to impact, the IP noted that the aircraft was below the glide path at 500 feet, and speed was at about 134 knots, with three red PAPI lights showing, and told the PF to pull back
  • Autothrottle was armed and set at 137 knots
  • between 500-200 feet, the IP noted that there was a lateral deviation and that the aircraft was low,
  • At 200 feet, the IP noted four red PAPI lights, that the speed tape was hatched (a visual indicator of an impending stall), and that the autothrottle had not maintained speed,
  • There was an automated 200 foot callout 18 seconds before impact,
  • There was an automated 100 foot callout nine seconds before impact,
  • Almost immediately after this 100 foot callout, a crew member mentioned airspeed (the NTSB noted that there were no mentions of speed heard on the CVR between 500-100 feet),
  • About three seconds before impact, there was a call for a go around,
  • The IP established a go around attitude, and went to push the throttles forward manually, but saw that the FP had already done so,
  • A second call made for a go around was made by a different crew member about 1.5 seconds before impact.

Crash sequence

  • The main landing gear hit the sea wall first, followed by the tail section,
  • The main landing gear sheared away from the aircraft as designed, and the wing fuel tanks were not punctured by the gear separation or during the the rest of the crash sequence,
  • Cabin flooring and galley components were found on the chevrons in the runway overrun area between the sea wall and the runway threshold,
  • The initial impact displaced rocks from the sea wall and some of them were distributed several hundred feet along the debris trail (see photo below),

    (click to enlarge)
  • All passenger seats stayed inside the cabin, but three flight attendant seats were ejected onto the runway,
  • Door 4L detached from the aircraft at some point in the crash sequence
  • Six of the 12 flight attendants were interviewed, and they stated that two of the eight escape slides inflated inside the cabin after a secondary impact (from a witness video, it appears that the aircraft rotated almost 360 degrees counter clockwise, with the rear of the cabin rising up at an angle before hitting the ground at the end of the crash sequence),
  • The right engine had detached from the wing, had rotated about 90 degrees counter clockwise, and was laying alongside the fuselage (see photo below).

(click to enlarge)

Post-crash actions and fire

  • After the aircraft came to a stop, the lead flight attendant (who was near door 1L) went to the cockpit for advice, and was advised not to initiate evacuation (see door layout in photo below),

    (click to enlarge)
  • Fire extinguisher switches were pulled for both engines and the auxiliary power unit,
  • The flight crew was able to communicate with the control tower, and the cabin crew was able to use the public address system to communicate to passengers,
  • A flight attendant who was trained as a lead flight attendant was at door 2L, saw fire outside door 2R near row 10 of the aircraft, and sent the other flight attendant at door 2L to the front of the cabin to inform the rest of the crew about the fire and the need to evacuate (in earlier briefings, the NTSB stated that the source of the fire was a ruptured oil tank that leaked fuel onto hot engine parts from the right engine),
  • Passenger evacuation began about 90 seconds after the aircraft came to a stop, escape slides were first deployed from door 2L and then from door 1L, and passengers also escaped from door 3R,
  • The control tower called for emergency vehicles after the aircraft hit the runway, the first vehicle arrived about two minutes after the crash, and extinguishing agent was first applied about three minutes after the crash,
  • Cabin emergency exit lighting came on during the evacuation,
  • There were six flight attendants who were injured and hospitalized: three seated in the rear of the plane who were ejected out onto the runway, another flight attendant in the rear who was injured, and two who were injured by the slides that deployed inside the cabin including one at door 1R and a second at door 2R,
  • The remaining six flight attendants had evacuated most of the passengers by the time the fire had spread to the cabin,
  • Aiport fire crews entered the cabin with a fire hose to help fight the fire,
  • Flight attendants helped to fight the fire with fire extinguishers, and also used the extinguishers to help extract the two flight attendants who were trapped by the two escape slides that deployed inside the cabin.

Cabin damage
Prior to the cabin fire, a firefighter entered door 2L and turned right to walk toward the rear of the cabin, and along the way observed that seats in that section were almost pristine, with minimal damage detectable, and that one could just fluff the pillows to get that section ready for the next flight. As he walked toward the rear, he observed more cabin damage, with a sharp contrast between the front and back of the passenger cabin. The photo below shows the pristine area of the cabin that was later damaged by fire.

(click to enlarge)

The NTSB structures team noted that from the cockpit to rear spar of the center wing box, the cabin floor was structurally sound. Aft from the rear spar to doors 3R and 3L, in the passenger seating compartment, support structure were compromised on the right side (flayed out from the aircraft), but still sound on the left side. Between doors 3 and 4, the floor was canted down at an angle, with damage progressively worse towards the back, and there was no cabin floor behind door 4.

Dr. Curtis and Capt. Tom Bunn discuss the crash
The day after the crash, Dr. Curtis of and Capt. Tom Bunn of the SOAR fear of flying program, who both spent several hours on the day of the crash on cable news programs providing expert commentary, discussed the media's response to the accident and shared their thoughts on the early reports of the crash.

Additional information 10 July 2013 article on the role of the autothrottle 8 July 2013 article on early findings of the crash investigation
Other Asiana plane crashes
Other 777 plane crashes
Accident details from Aviation Safety Network
Wikipedia page on this accident

Photos: Wikipedia, NTSB

10 July 2013

Asiana 777 accident investigation and the role of the autothrottle

During the Tuesday, 9 July 2013 NTSB press conference, numerous facts about the accident were revealed, including details about the training and experience of the pilots in the cockpit, and the fact that the initial impact not only tore the tail section off the aircraft, but also caused two flight attendants seated in the rear of the aircraft to be ejected out of the cabin. Both survived, but were injured.

Perhaps the most revealing information from the conference was evidence gathered from statements from the pilots, that seemed to indicate that the while the pilots had planned to use the autothrottle to control the aircraft's airspeed during landing, the autothrottle was not engaged at the time the crew was attempting to execute a go around in order to attempt another landing.

The NTSB emphasized that this was preliminary factual information that has yet to be corroborated with other data from sources such as the flight data recorder. However, it implies that one of two possible scenarios may have occurred during the latter stages of the flight:

  1. The crew intended to use the autothrottle, but did not take all the steps needed to engage the autothrottle, or
  2. The flight crew took steps to engage the autothrottle, but the autothrottle either did not engage or it disengaged at some point.

Basic autothrottle operation
In order to understand the possible significance of these preliminary NTSB findings, it helps to have a bit of background knowledge on how autothrottles are used.

In the 777, as in many modern airliners, the autothrottle allows a pilot to control the power setting of an aircraft's engines automatically rather than manually. Flight crews use the autothrottle to maintain, or try to attain a particular value for either speed or thrust without having to manually adjust throttle settings. For example, a pilot may want to maintain a specific airspeed, and would use the autothrottle to maintain that airspeed while the pilot may be manually controlling other aspects of the flight.

The autothrottle can also enhance safety by keeping the aircraft within safe operating limits. For example, if the pilot commands the autothrottle to attain a speed that is at or below a minimum safe speed or above a maximum safe speed, the autothrottl will not allow the aircraft to fly at those unsafe speeds.

Arming and engaging the autothrottle
In the 777, using the autothrottle to control airspeed is a two-step process. First, the autothrottle has to be armed using two switches (one for each engine) on the mode control panel (MCP). Being armed means the autothrottle is available to be used. The second step is to engage the autothrottle, which means it is now being used to control airspeed. The autothrottle is engaged by using an appropriate switch on the mode control panel.

Mode control panel
The cockpit of many modern airliners, including the 777, have a mode control panel (MCP), which contains the controls that the flight crew would need to automatically manage the aircraft's flight, and in the 777, the MCP controls a number of functions, including the autopilot and autothrottle.

Below are two photos depicting the 777. The first is a representation of the MCP from a NASA computer simulator, and the second is from the cockpit of a 777 and shows both the MCP and several cockpit display screens. Note the neither one may represent the exact configuration of the MCP in the Asiana accident aircraft.

(click to enlarge)

(click to enlarge)

The following video describes how a simulated version of the 777 MCP behaves. The first couple of minutes describes how the autothrottle has to be armed before it can be engaged and used to control speed.

Is the autothrottle the key to the cause of the accident?
The NTSB emphasized in their press conference that all of the information that they have released so far is factual in nature, and that they have no intention of speculating or deciding upon a cause or causes of the accident at this stage of the investigation. Also, the information gathering stage of the investigation is ongoing, and there may be other facts that the NTSB either has not yet discovered or has not yet released to the public.

Another perspective on this accident
For an excellent perspective on this accident and the revelations from the early part of the investigation, I highly recommend the Slate article of Patrick Smith, a professional airline pilot and recent guest of the podcast.

Dr. Curtis and Capt. Tom Bunn discuss the crash
The day after the crash, Dr. Curtis of and Capt. Tom Bunn of the SOAR fear of flying program, who both spent several hours on the day of the crash on cable news programs providing expert commentary, discussed the media's response to the accident and shared their thoughts on the early reports of the crash.

Additional information 13 July 2013 article 10 July 2013 article on the role of the autothrottle 8 July 2013 article on early findings of the crash investigation
Other Asiana plane crashes
Other 777 plane crashes
Accident details from Aviation Safety Network
Wikipedia page on this accident

Photos:, NASA

08 July 2013

Early findings in the Asiana 777 crash investigation

6 July 2013; Asiana Airlines 777-200ER; HL7742; flight 214;San Francisco, CA: The aircraft was on a schedule international flight from Seoul, South Korea to San Francisco, and the rear of the aircraft struck a seawall just short of the runway while landing. The tail section broke apart, and both horizontal stabilizers and the vertical fin separated from the aircraft. Both engines and the main landing gear also separated from the aircraft.

In the photo on the right, the vertical fin and horizontal stabilizers (also called the tailplane) are very early in the debris trail, and in the overrun areas just before the runway threshold.
The aircraft caught fire after it came to rest, but not before all of the crew and most of the passengers were able to escape. All 16 crew members survived, but two of the 291 passengers were killed.
In the NTSB press conference on Sunday July 7th, the day after the accident, the NTSB revealed a variety of preliminary information about the sequence of events that led to the crash, including the following:
  • Prior to the crash, the aircraft did not experience any significant problems with performance or with its systems,
  • Both the cockpit voice recorder and the flight data recorder (the black boxes) were recovered and were being evaluated by the NTSB
  • The pilots had stated that their intended landing speed was 137 knots, but at the time of the crash the aircraft was flying at a substantially slower speed,
  • The data indicate that the throttles were at idle and the airspeed slowed below target approach speed during the approach,
  • Sound of stick shaker (indicating an impending stall) began about four seconds prior to impact,
  • The throttles were advanced a few seconds prior to impact and the engines appear to respond normally.
  • The crew stated an intention to execute a go around about 1.5 seconds before impact, and
  • The crew did not transmit any kind of distress or emergency call.
On Sunday, Asiana Airlines also revealed that the pilot responsible for performing the landing had landed other aircraft at San Francisco's airport, but the accident flight was the first time the the pilot had attempted to land a 777 at that airport.
Given the distribution of the wreckage in the debris trail, both horizontal stabilizers, the vertical fin, and at least two of the three landing gear separated very early in the crash sequence, making it very unlikely that the crew would have been able to keep the aircraft on the runway.
Crash video released
On Sunday, CNN released a video taken from near the airport that shows the entire crash sequence. The video shows that the aircraft rotated counter clockwise after the tail section separated, and the rear of the fuselage was lifted up at least 20 feet before it slammed down on the ground. It is possible that much of the serious structural damage seen at the rear of the fuselage, including a ruptured aft pressure bulkhead, occurred when this part of the plane slammed down toward the end of the crash sequence.
Status of landing aids
While one of the navigational aids on the landing runway (28L) that provides glide slope guidance was not operational, this should have been known to the crew because it was published as a notice to airmen (NOTAM), and there were several other options that the crew could have used for approach guidance. Since aircraft were landing under visual flight (VFR) rules at the time, there was no requirement to use these landing aids.

NTSB photos

Dr. Curtis and Capt. Tom Bunn discuss the crash
The day after the crash, Dr. Curtis of and Capt. Tom Bunn of the SOAR fear of flying program, who both spent several hours on the day of the crash on cable news programs providing expert commentary, discussed the media's response to the accident and shared their thoughts on the early reports of the crash.

Additional information article 13 July 2013 article article 10 July 2013 article on the role of the autothrottle
Other Asiana plane crashes
Other 777 plane crashes
Accident details from Aviation Safety Network
Wikipedia page on this accident
Photos: BBC, Getty Images, NTSB