Click for next page ( 86


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 85
s Recommendations The committee's recommendations are listed under four broad categories: general, detection and prediction, aircraft performance and operations, and research. The numbering of the recommendations does not signify any priority. The broad spectrum of specific recommendations reflects the complexities of the low-altitude wind-shear problem. GENERAL 1. NEED FOR AN INTEGRATED WIND-SHEAR PROGRAM To provide for the safety of the flying public, the FAA and the aviation industry should address the many facets of the low-altitude wind-shear problem as a whole. The FAA should develop and implement a coherent and sustained program for coping with the educational, meteorological, technological, and operational aspects of low-altitude wind-she ar haz ard s . 2. WIND-SHEAR EDUCATION PROGRAM The FM and the industry should prepare and disseminate as widely as possible updated and authoritative information on wind shear. Informational materials should stress avoidance of wind shear and should describe flight control techniques for recovery from encounters . The information should encompass al 1 of types of aircraft, with appropriate guidance for each class. It should include recommendations on the most effective means of training pilots. The FAA should revise and update its 1979 advisory circular (AC 00-50A) on wind shear and the Airman's Information Manual (AIM) to present the latest information, including detection techniques, alerting and warning procedures, effects of wind shear on aircraft performance, and procedures for recovery from wind shear encounters. 85

OCR for page 85
3. PILOT/CONTROLLER COMMUNICATIONS The FAA should promote the us e of s tandardized terminology and improved communications between flight crews and control towers. A standardized system of pilot reports (PIREPs) should be developed for reporting low-altitude wind shear encounters. PIREPs should be mandatory and should include a report of the location, severity, and nature of the shear encountered--in consistent, standardized terminology. Controllers should communicate such reports to all flight crews in the vicinity. In addition, techniques for the direct broadcast to pilots of wind shear data from LLWSAS or other sensors should be investigated. 4. WIND SHEAR DETECTION SYSTEM DEVELOPMENT The FAA should select a site to test direct and remote-sensing techniques in a complete system for detecting low-altitude wind shear and for providing information to pilots and controllers and to test the use of the information in the air traffic control system. The test site should be at a major airport where wind shear conditions are relatively frequent. DETECTION AND PREDICTION 5. THE LOW-LEVEL WIND SHEAR ALERT SYSTEM (LLWSAS) LLWSAS is the only system currently available in the near term for detecting low-altitude wind shear on an operational basis and every effort should be made to assess and improve its performance. Opportunities include, but are not limited to, better signal processing, reduced spacing between and increased number of sensors, improved sensor response and improved wind-display techniques and criteria for issuing wind-shear warnings, and the use of ground-based pressure sensors to augment LLWSAS information. An improved LLWSAS system is being developed for installation at New Orleans International Airport. This upgraded system, to be operationally tested in early 1984, should provide the basis for modification of current LLWSAS installations and for improved system performance for future installations. Depending on the New Orleans test results, the FAA should modify existing LLWSAS systems and install improved systems at all high-traffic density airports with terminal automation systems (153 airports) where there is likelihood of the occurrence of dangerous wind shears. 6. RECORD AND ANALYZE LLWSAS DATA LLWSAS wind measurements should be recorded and analyzed to evaluate the system's performance and to learn more about the climatic properties of low-altitude wind shear. This should be done at all airports equipped with LLWSAS. 86

OCR for page 85
7. USE OF AVAILABLE RADAR DATA The existing network of weather radars, operated by the NWS, should be used more effectively to judge the likelihood of wind conditions. These radars detect rain showers, thunderstorms, and phenomena often associated with wind shear. Information from weather radars should be made available to air traffic controllers in a timely and easily understandable fashion. 8 . NEXT GENERATION WEATHER RADAR (NEXRAD ) The next generation Doppler weather radar system (NEXRAD) should be developed and installed with all possible speed. This long-range radar system will serve many national needs related to severe-weather detection, forecasting, and warning. For aviation, the NEXRAD system can be used to detect and monitor weather situations along flight routes and, if located at or near some airports, to detect low-altitude wind shear or its precursors. Moreover, the Doppler radar will advance the rate of development of radar techniques for the detection of low-altitude wind shear and the development of dedicated Doppler terminal radars. 9. AIRPORT TERMINAL WEATHER RADAR The FAA should take immediate action to develop a pulsed Doppler radar system that can be used to observe weather conditions at and around airport terminals. This terminal radar system should be able to operate with a high degree of automation and to provide information on low-altitude wind-shear, turbulence, and rainfall intensity. Such a radar must be capable of supplying information updated each minute and must have such features as ground-clutter cancellation and adequate spatial resolution. 10. USE OF AIRPORT TERMINAL WEATHER RADAR OBSERVATIONS For terminal Doppler radar to be most useful to traffic controllers and pilots, a concerted effort should be devoted to developing procedures for analyzing, displaying, and using its observations. 11. AIRBORNE REMOTE SENSORS Research should continue on the use of airborne Doppler lidars and microwave Doppler radars as a means for detecting low-altitude wind shear. AIRCRAFT PERFORMANCE AND OPERATIONS 12. WIND-SHEAR EFFECTS ON FLIGHT CHARACTERISTICS The FAA should sponsor analytical and simulator investigations to determine: 87

OCR for page 85
o The wind shear penetration transport aircraf t, based on various guidance, and control systems. and recovery capab i 1 ities of onboard do te cam ~ i On The effects of wind shear on various typical categories of general aviation aircraft and helicopters so that authoritative information on their response characteristics and pilotin techniques in wind shear can be provided. 13. AIRCRAFT OPERATING PROCEDURES The FAA should ensure that air carriers and other commercial operators instruct flight crews on what to do if they inadvertently encounter a l.o~altitude wind shear during takeoff or landing. In addition, the FAA should encourage operators of jet aircraft to incorporate in their manuals the operating procedures recommended in its advisory circular on wind shear. Aircraft manufacturers should recommend configuration-change sequences (gear, flaps, power, spoilers, etc. ~ that provide the highest probability for recovery from a wind shear encounter. Pilots should be taught to exceed the normal maximum thrust limits and to go to emergency thrust when necessary. 14. GUIDANCE AND CONTROL AIDS Onboard sensors and guidance aids should be evaluated in a systematic manner to determine their merits for future development and for possible retrofit in existing aircraft. These include flight director modifications, ground speed/airspeed flight management systems, vertical-acceleration sensors, and energy-rate sensors. Angle-of-attack indicators should be added to the cockpit instrumentation of transport aircraft for use in maneuvering through wind shears . Angle o f attack should be provided either as a separate variable or as an input to other command displays. Sensors should provide flight crews with a voice warning of a hazardous wind shear. 15 . STANDARDI ZATION OF WIND-SHEAR MODELS The FAA should spons or a program to devel op and de fine standardized models of wind shear based on the latest meteorological data. These models are required for design and certification of aircraf t subsystems and for use in training simulators. The FAA should include other government agencies, aircraft manufacturers, commercial operators, and any other interested parties in the program. 16 . CE RT IF I CAT I ON OF ONBOARD SY STEMS The FAA should update its certification requirements for airborne wind-shear alerting, flight guidance, and automatic control systems. 88

OCR for page 85
17. WIND-SHEAR SIMULATION TRAINING The FAA and the industry should cooperate to investigate new and innovative ways to make available the best possible simulation training for wind shear to the largest possible number of pilots, including general aviation pilots. RESEARCH 18 . EFFECT S OF HEAVY RAIN Inves tigations should aerodynamic Ha ~ ~ ~ ~ . cant inue on charac teris t ics how heavy rain af fects the low-speed aerodynamic characteristics of aircraft. Particular attention should be paid to the possible adverse effects of heavy rain on aircraft lift, performance, and controllability, including its effects on wind shear detection and flight sensor systems. 19 . RE SEARC H ON THE NATURE OF LOW-ALT ITUDE WIN1) SHEAR More must be learned about the various kinds of wind shear and the meteorological conditions that cause or are associated with them. This knowledge is needed to reduce the hazards represented by low-altitude wind shear. Research should include additional field observations and the construction of theoretical models over the relevant scales--from about 1,000 feet to 10-20 miles and from minutes to hours. The existing body of data obtained by various research should be reexamined and augmented, at an appropriate time, by a programs .. ~ field ~~ ~ ~~ ~ ~ the data field program In the numlo southeastern united states. Analyses or obtained from the JAWS Pro ject should be used to plan any new investigation. Basic research into the origins of strong thunderstorm downdraf ts and possible forecast methods should be an important component of any new program. 89

OCR for page 85