Industry's Role in Aviation Safety

From the very earliest days of commercial flight, airlines, aircraft manufacturers, pilot organizations and other segments of the aviation industry have teamed with governments and international organizations to make flying as safe as possible.

While the industry is highly competitive, it also is highly cooperative when it comes to identifying and addressing safety issues. Information is shared freely as pilots, airlines and aerospace companies work together with government aviation leaders to address safety challenges.

Each segment of the industry also has clearly defined responsibilities and roles to play, as do governments.

Learn more about the things that aircraft manufacturers and the airlines do to ensure safety:

• Manufacturers
  
• Airlines
  

Manufacturer's safety role
The Boeing Company designs, manufactures, assembles commercial airplanes. The company is dedicated to delivering the safest, most reliable and most technologically advanced airplanes that can be produced. Quality and safety are the top priorities. Just as Boeing is proud of its level of excellence, it is always striving to better its best.

The following pages describe the Boeing commitment to safety:

• Boeing technology philosophy
  
• The flight envelope
  
• Airplane design and analysis
  
• Human factors engineering
  
• Upgrading airplanes
  
• Lifetime safety cycle
  
• Future safety enhancements
  
• Fire prevention systems
  
• Flight crew training
  

Boeing will not use new technologies, or the capabilities they make possible, unless they provide distinct safety, operational, or efficiency advantages and do not compromise existing safety.

Advancements that fail this simple test simply do not fly aboard Boeing jetliners. Why? Because the ill-considered application of new technologies can lead to unintended consequences that compromise the safety already achieved.

Airplanes are designed and certified to operate within a specific set of structural and aerodynamic parameters (e.g., weight, speed, range), which are called the "flight envelope." Engineers, however, build in extra protection, so planes are tested and put through their paces on maneuvers that "exceed the normal flight envelope." These are extreme cases that most pilots will never see in commercial service, but this extra margin of protection is built in to allow a pilot to safely exceed the "flight envelope" in case of emergency.

Airplane Design And Safety Analysis

Airplanes are designed and built to anticipate and avoid problems. In fact, airplanes are designed to function at full capacity even if something has gone wrong. Airplane systems have double and triple redundancy features built in to minimize the likelihood of a real problem occurring.

Whether designing a new airplane or upgrading a member of the existing fleet, engineers specify tests and systems to analyze their designs:

• Functional hazard assessment--identifies and categorizes conditions that might result in a system failing or other serious consequences to the airplane.
• Failure modes and effects analysis--systematically identifies system-and component-level failure modes and then looks at the effects on the design.
• Fault-tree analysis--assesses the likelihood and effects of combined failures within a given system.
• System separation and survivability analysis--assesses the ability of an airplane’s systems to survive damaging events and identifies changes to enhance the likelihood that the plane and passengers will survive an accident.

These tests are intended to simulate and predict how a plane will behave if something goes wrong, as well as determine if the systems in place are adequate. Engineers use these diagnostic tools to make adjustments or corrections to ensure the safety of both the current model and future airplanes.

Airplanes are designed to last far longer than the minimum certification standards required by the FAA. Airplanes are thoroughly analyzed and examined during every phase of design and flight-testing. Extra margins are factored, in terms of the requirements for operating and maintaining an airplane.

Boeing is leading the aviation industry in studying and applying human factors engineering lessons to the design of commercial airplanes. This involves gathering information about human abilities, limitations and other characteristics. The data is then applied to tools, machines, systems, jobs and processes. The results are intended to produce safer or improved interaction between humans and machines.

In aviation, human factors is dedicated to better understanding how humans can most safely and efficiently be integrated with technology. A sound scientific basis is necessary for assessing human performance implications in design, training, and procedures, just as developing a new wing requires sound aerodynamic engineering.

Boeing addressed this issue by employing human factors specialists, many of whom are also pilots or mechanics. Initially focused on flight deck design, this group now considers a much broader range of elements such as cognitive psychology, human performance, physiology, visual perception, ergonomics, and human-computer interface design. Applied collectively, their knowledge contributes to the design of Boeing airplanes and support products that help humans perform to the best of their capability while compensating for their natural limitations.

Error management
In addition to improving design, Boeing human factors engineers also develop error management tools. Two such tools are the procedural event analysis tool (PEAT) and the maintenance error decision aid (MEDA). Boeing is committed to helping commercial airplane operators fly safely and learn from the latest information uncovered by human factors engineers.

• PEAT is the first analytic tool of its kind adopted industry wide. It was created to help the airline industry manage the risks associated with "deviations to procedure" by the flight crew. PEAT assumes an error is just that - an accident. Following an incident, investigators research the causes that led to the deviation and enter this information into a database for further study.
• An effort to collect maintenance error data developed into MEDA. This tool is based on the idea that errors result from a series of factors or incidents. The goal of using MEDA is to investigate errors, understand root causes and prevent accidents, rather than place blame on maintenance personnel for errors.
  

Because engineers do not want to make a problem worse or create a problem that didn't exist in the first place, they must make certain that each change has been thoroughly tested. All intended and unintended consequences must be identified beforehand. There are more than three million parts in a jet airplane. Each system is highly integrated. One particular part does not operate in isolation; rather, it may serve several functions. Each part directly affects another part.

Each enhancement or change is first implemented in a single airplane. After extensive flight-testing and analysis, the improvement is rolled out to other aircraft. Only after a modification has been tested and approved by Boeing engineers and government regulators can an airplane be upgraded.

Boeing makes sure it hears about the "lessons learned" by airlines as they fly the airplanes around the world. Boeing design processes include a feedback loop called the "lifetime safety cycle," which returns this invaluable information so that the Company can continue to upgrade its airplane designs, manufacturing process and support of the in-service fleet. During the validation and certification testing of all new Boeing jets, and then for as many decades thereafter as each jetliner type remains in service, countless opportunities are seen for design improvements.

One uses signals from global positioning satellites to guide aircraft all the way down to a runway, freeing pilots from dependence on less capable and more expensive instrument landing systems on the ground.

Also being studied are several new display technologies for flight decks. One is a "vertical situation display" that will give pilots an intuitive graphic of their descent profile and surrounding terrain. Another is a "taxi display" that will depict all ground traffic around an aircraft while it is taxiing to or from a gate and that will alert pilots to potential collisions. A third display technology will help pilots better cope with complex procedures and heavy workload situations.

Out in the future even farther, but actively being pursued are technologies that could help alleviate wake vortex and mitigate turbulence.

"Synthetic vision" is the term used for an exciting technology that someday could give pilots better situational awareness. Combining information about an aircraft's position with terrain data stored in a computer, such a system would create a synthetic picture of what's ahead at any given moment. Flight crews would have day-like visual flight conditions even in low-visibility situations.

Boeing also is working on diagnostic systems that would monitor all other systems aboard an aircraft for signs of developing problems. These systems would give flight crews early warning of such problems so components could be replaced before they fail, thereby eliminating unscheduled maintenance.

The training aids help prepare flight crews for the following safety challenges:

• Wind shear
  
• Takeoff safety
  
• Volcanic ash
  
• Wake turbulence
  
• Controlled flight into terrain
  
• Turbulence
  
• Airplane upset recovery
  
• Tail strike avoidance
  

Wind shear
Wind shear is a sudden change in the wind's speed or direction, often involving strong side-by-side updrafts and downdrafts. It may occur in conjunction with a thunderstorm or other bad weather and can appear with little or no warning.

The seventh most common cause of fatal jet accidents worldwide during the past 10 years, this weather phenomenon can have deadly consequences for a jetliner if it is encountered near the ground. Wind shear can also overwhelm an airplane's ability to descend or climb safely.

The rate of wind shear accidents has dropped dramatically in recent decades. Dealing with wind shear is an industry success story, due in part to the implementation of a Wind Shear Training Aid, created collectively by Boeing, the FAA and a consortium of aviation specialists.

Today, flight crews know how to fly safely out of a wind shear situation; they practice these techniques in full-flight simulators.

Airplanes are also equipped with onboard reactive and predictive alerting systems to enable pilots to be aware of and avoid wind shear situations. Additionally, ground-based Doppler radar capable of detecting some forms of wind shear is being made available to more and more airports.

Takeoff safety
A flight crew may reject a takeoff for a variety of reasons, including engine failure, direction from air traffic control, blown tires, or system warnings. A takeoff under these conditions may result in a diversion or delay, but landings are usually uneventful. In about 55 percent of rejected takeoffs (RTOs) the airplane would have had an uneventful landing if the takeoff had gone ahead.

While most RTOs are without incident, they do account for a significant number of accidents, as well as damage to the airplane. Following are some statistics about RTO accidents and incidents:

• More than half the RTO accidents and incidents reported in the past 30 years were initiated from a speed in excess of the maximum "go/no go" speed before the airplane must take off.
  
• Approximately one-third reportedly occurred on runways that were wet or contaminated with snow or ice.
  
• A little over one-fourth of RTO accidents and incidents were caused by loss of engine thrust.
  
• Almost one-fourth of RTO accidents and incidents were the result of wheel or tire failures.
  
• Approximately 80 percent of RTO overrun events could have been prevented by appropriate operational practices.

An RTO occurs approximately once in every 3,000 takeoffs. However, many RTOs may not be reported; the actual number may be estimated at one in 2,000 takeoffs. While RTO overrun accidents and incidents persist, the rate of occurrence continues to drop. Compared to the 1960s, the 1990s showed a 78 percent decrease in the rate of RTO overrun accidents and incidents.

In 1992, with the endorsement of the FAA, Boeing, along with members of the aviation industry, published the Takeoff Safety Training Aid. The aim of this training aid is to reduce the number of overrun accidents and incidents resulting from high-speed rejected takeoffs. Boeing and members of the aviation industry also formed an international takeoff safety task force that recommended developing training practices and operational guidelines and improving how the full-flight simulator is used.

Engine, tire and brake suppliers are also working to improve their products. The airlines are continuing to develop effective training in the areas of takeoff decision-making and how to handle rejected takeoffs.

Volcanic ash
Around the world there are a number of active volcanoes. While most are not erupting every day, the potential for encounters between airplanes and volcanic ash still exists. Thankfully, the number of airplanes that have come in contact with volcanic ash has declined over the past several years, due in part to the Volcanic Ash Training Aid.

Volcanic ash can render radar ineffective and can affect airspeed, engine conditions and pressurization. Encounters with volcanic ash can have safety- and maintenance-related consequences. As a result, members of the aviation industry have worked with volcano scientists to develop a plan for volcanic ash awareness and avoidance. This plan includes three key steps: avoidance, recognition and procedures to cope with a situation.

Volcano observatories now provide daily updates about current conditions; the Internet is also a well-used tool to supply information. Additionally, flight operations procedures carefully detail what to do in the event of a volcanic ash encounter so that flight crews can deal with the situation appropriately.

Wake turbulence
Wake turbulence is a natural part of flying. All airplanes produce wake turbulence.

In order to generate lift, low- and high-pressure air passes over and under an airplane's wing, forcing airflow at the wingtip to swirl downstream. Similar swirls come off the ailerons, flaps, spoilers and other parts of the wings and tail of the plane. This swirling is called a wake vortex.

The intensity or strength of a vortex is related to an airplane's weight and configuration. Heavier airplanes produce stronger vortices. Flight crews must exercise extra caution when they fly below and behind large airplanes. Distances are mandated by federal regulations.

Boeing is currently developing a system that shows promise for alleviating trailing vortices behind "flaps-down" commercial airplanes within distances less than current approach separations. The system uses airplane control surfaces to oscillate a small fraction of the wing lift between inboard and outboard sections of the wing in order to trigger wake instabilities that destroy the vortices. The system has been demonstrated in ground-based testing, but there still are outstanding technical issues and the system must be validated in flight.

The Boeing Company and the aviation industry together created a Wake Turbulence Training Aid. This training aid aims to build situational awareness and dispel misconceptions about this hazard. Both flight crews and air traffic controllers need to understand the fundamentals of wake turbulence and to accurately perceive current conditions that affect the safe operation of an airplane.

This training aid also educates pilots and air traffic controllers about the effects of wake turbulence and how to avoid it, detect it, evade it and recover from it. The Pilot and Air Traffic Controllers Guide to Wake Turbulence provides the framework for a ground-based training program.

Controlled flight into terrain
Controlled flight into terrain (CFIT) describes an accident in which a flight crew unintentionally flies an airplane into the ground, a mountain, water or an obstacle. It is a leading cause of airplane accidents involving the loss of life. There have been more than 9,000 deaths due to this since the beginning of the commercial jet age.

There are many reasons why a plane might crash into terrain, including bad weather, imprecise navigation and pilot error. In fact, pilot error is the single biggest factor leading to a CFIT incident.

Thankfully, this sort of tragedy is occurring less frequently, due in part to an Enhanced Ground Proximity Warning System and a CFIT Training Aid. The Boeing Company - in partnership with airframe manufacturers, avionics suppliers, airlines, pilots, and government and regulatory agencies - developed this now widely adopted initiative.

The Training Aid includes a comprehensive training package of written and audio-visual materials. Flight crews combine classroom-based learning with time spent in a full-flight simulator. The training aid has been so successful that the Flight Safety Foundation has distributed it to many non-Boeing operators.

Turbulence
Clear air turbulence is a natural occurrence, but a serious aviation issue because it is a major cause of injuries. As a result, The Boeing Company and members of the aviation industry have created a Turbulence Training Aid to assist flight crews in identifying and avoiding severe patches of turbulence.

The Turbulence Education and Training Aid is an educational resource for flight crews, flight attendants, air traffic controllers, meteorologists and others within the aviation industry. Designed to increase awareness, this training aid encourages establishing and following a procedure to avoid turbulence and adverse weather systems. The aid also teaches flight crews what to do when they encounter turbulence.

As part of the current training aid, flight crews are encouraged to make use of Doppler radar, turbulence plotting, flight crew reports of turbulence and adverse weather, and automatic uplinks through the Aircraft Communication Addressing and Reporting System. The aviation industry is also working to develop new systems to detect turbulence and provide an early warning to flight crews.

Airplane upset recovery
Airplane upset is synonymous with an out-of-control airplane. The following conditions are considered airplane upset:

• An airplane's nose pitching up more than 25 degrees or down more 10 degrees.
  
• An airplane banking at more than a 45-degree angle.
  
• An airplane flying within the appropriate parameters but not at the appropriate airspeed.

A variety of causes — singly or in combination — can lead to airplane upset:

• Environmental conditions including weather.
  
• A systems failure.
  
• Pilot error.

The Boeing Company and members of the aviation industry are working to minimize the risk of airplane upset and to enhance aviation safety. Together they have developed the Airplane Upset Recovery Training Aid, which is designed to help pilots recover an airplane that is upset or out of control. One goal of the training aid is to enable a pilot to recognize and avoid situations that lead to airplane upset. Another objective is to improve a pilot's ability to recover from an airplane upset. To achieve these goals, simulator- and classroom-based training has been made available industrywide.

Tail Strike Avoidance
A tail strike occurs when an airplane’s tail impacts a runway during a takeoff or landing. Although some airplanes experience tail strike more often than others, all commercial jets can encounter tail strikes, and frequently the pilots cannot determine what caused the event.

The Douglas Products Division, now a part of The Boeing Company, examined tail strike incidents and took into account weather conditions, flight data recorder information and interviews with flight crews. Researchers discovered that there are separate risk factors for takeoff and landing. Although a tail strike during takeoff is significant, a tail strike on landing tends to cause more serious damage and is more expensive and time consuming to repair.

One important cause of a tail strike is inexperience on the part of the flight crew. Simulator practice, use of a Boeing-developed training aid and a better understanding of pitch attitudes can all help a pilot avoid the risk of tail strike.