Flight 587 - questions and answers
How do wake vortices threaten aircraft?
Wake vortices are powerful tornadoes of air which spin off the wing tips of aircraft during take off and landing. Wake vortices can be a danger to aircraft caught in their path as they throw the plane off its normal course, usually causing them to bank dramatically to the left or right. The effect of the vortices depends on the size of the following aircraft, with smaller aircraft being in more danger than larger ones. The speed at which these vortices rotate, their power, and the rate at which they dissipate depends on the size of the aircraft by which they are generated, and on climatic conditions.
In order to protect commercial air travel against dangerous wake vortex encounters, there is a standard minimum distance of two minutes between each aircraft taking off and landing.
What are the advantages and disadvantages of using composite materials in aircraft manufacture?
For many years the majority of aircraft load bearing structures were built from aluminium. Airbus was the first company to build an aircraft using laminated composite fibres in their load bearing structures - such as the tail on their A300 series aircraft.
Composite materials are lighter than metals for the same strength and so the trend to use them in aircraft manufacture is increasing. Saving weight means the aircraft can carry more passengers. The main disadvantage of composite fibre components is that they are able to conceal damage and wear and tear. Visual inspections may not notice a problem that would be apparent in an aluminium structure.
Who is responsible for ensuring aircraft safety?
In the USA, the responsibility of ensuring aircraft safety falls to the Federal Aviation Administration (FAA) which is in charge of issuing the industry's certification standards. This includes determining the structural design certification to which a plane must be built, and the limits which it must be able to withstand during both normal flight and during the aircraft's lifetime. The FAA can also issue an Air Worthiness Directive when it has identified an unsafe condition relating to the way in which aircraft are flown.
Aircraft manufacturers can issue Service Bulletins to airlines (relating to things like aircraft maintenance) but these bulletins are simply recommendations, they are not mandatory.
The National Transportation Safety Board has the power to issue safety recommendations to the FAA which detail how all aircraft, regardless of make and model, must be flown safely. These are recommendations, they too are not mandatory.
How are planes certified for public use?
All aircraft are certified for public use in the USA by the Federal Aviation Administration. It specifies the design limits to which all aircraft need to be built and tested.
How is a plane crash investigated?
Each country has a government funded investigating body which examines the cause of air crashes. In the United States, the responsibility for this falls to the National Transportation Safety Board (NTSB), based in Washington. The investigation is covered by numerous experts, each specialising in specific areas potentially relevant to the cause of the crash.
How is responsibility for a crash determined?
In cases of great public interest, the NTSB will conduct a public hearing to show how the investigation is progressing, and to show which avenues of thought the investigators have considered. Each party with an interest into the investigation is invited to attend, and to question one another about specific areas needing clarification.
Is this the same as a court of law?
A public hearing assesses the progress of the investigation. It does not constitute legal proceedings, and does not explicitly draw any conclusions or ascertain blame. The investigation continues after the public hearing.
Is it safe to fly in an Airbus A300-600?
Airbus Industrie stand by the integrity of their plane. American Airlines continue to operate the Airbus A300. Both companies have acted upon industry-wide amendments to ensure that the aircraft is safely operated.