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for the rudder and vertical stabilizer on the airplanes pilots fly. Significantly full rudder
inputs, even at speeds below maneuvering speed, may result in structural loads that
exceed certification requirements” (31).
Unfortunately, it took a tragedy for these shortcomings to come to light. Maneuvering
speed is incorrectly defined by the FAA—leading the aviation community to incorrect
assumptions about the protections it affords.
4. Aircraft Separation Standards
The current three-class separation standards between aircraft are inadequate and present a
hazard to all aircraft operating today. These standards were developed using dated
information about aircraft vortices and have not been updated as aircraft weights
approach 1 million pounds. New testing of the “super-heavy” generation of aircraft must
be accomplished to mitigate the risk which grows as aircraft weights grow.
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Many argue that simulations currently exist to accurately predict the wake vortices of
aircraft as they grow in size and change in their wing design. The Safety Board clearly
states in the response to Safety Recommendation A-94-043 that:
“The Safety Board has no evidence that the FAA/NASA wake vortex simulation has
sufficient validity to define risk in an actual wake environment. The Safety Board does
not believe that unvalidated [sic] theoretical evaluations should be used to justify
decreased safety margins such as exemptions to the weight classification system.”
The Board’s genuine concerns are further delineated in Safety Recommendation A-95-
056. This recommendation would require manufacturers “to determine, by flight test or
other suitable means, the characteristics of the airplane’s wake vortex during
certification.” This recommendation’s status is “Open/Unacceptable Response.” The
FAA justifies its classification of new aircraft within the existing separation standards by
citing the safety record established by those standards. This weak argument was defeated
when AA 587 encountered a wake of unknown intensity.
The Board concludes the open recommendation with the statement:
“By testing all new aircraft, the FAA would know how they compare to existing aircraft
and would be able to scientifically determine what adjustments to separation distances
may be necessary. The Board continues to believe that the FAA needs to determine the
characteristics of all transport-category airplanes’ wake vortices during certification.”
The NTSB has shown valid concerns about the wake vortices emanating from new
“super-heavy” aircraft. It is time for the FAA to acknowledge those concerns and act. AA
587 encountered the wake from a 747-400. The wake vortices from this late model 747
have never been measured and are virtually unknown in strength. New separation
standards must be established to protect all aircraft operating in the National Airspace
System (NAS) from this unknown threat which will continue to propagate as aircraft
continue to grow.
Safety Recommendation 8
The NTSB should recommend that the FAA Office of System Safety
(OSS) review the findings of the AA 587 investigation to determine
why these system safety failure s occurred. This effort should include a
team of qualified individuals from industry and government,
including representatives of the French DGAC and FAA certification
officials. The stated goal of the review should be to identify and
understand the system safety failures so as to prevent, if possible, the
re-occurrence of a tragedy like AA 587.
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Safety Recommendation 9
Safety Recommendation 10
The NTSB should recommend that the FAA more specifically define
the definition of ‘maneuvering speed,’ as it pertains to all categories of
aircraft and, in so doing, clearly outline the differences of assumptions
as they apply to the three primary flight control surfaces. All
manufacturers’ flight manuals and other associated documents for
airplanes certified in or imported into the United States accordingly
should also be revised to reflect the proper meaning and use of the
term ‘maneuvering speed.’
The NTSB should recommend a much more aggressive compliance of
system safety practices as outlined in the FAA System Safety
Handbook. The Assistant Administrator of System Safety (ASY) and
office staff should be empowered to act as an independent technical
authority to ensure system safety practices are used through the life
cycle of the various systems receiving FAA approval or certification.
The NTSB should revise Safety Recommendation A-96-64 to the FAA,
re-emphasizing the pertinence of the recommendation to aviation
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