Landings Altitude Standard dev. Mean 1 909 30–300 m 0.89 0.20 0.6 0.4 0.2 0.0 Fre quenc y of oc cu rre nc e
Along-track wind change/30 m
Figure 3-26. 50%, 5% and 1% probabilities of exceeding along-track wind change/30 m per landing, versus height
(from Haverdings, 1980, and adapted by ICAO)
300 200 100 He ig ht (m ) 0 –10 –5 0
Along-track wind change/30 m
5 m/s–1/30 m 10 Median Schiphol, 1977–1978 1 917 landings 5% probability of exceeding wind change/30 m 1% probability of exceeding wind change/30 m
c) this film of water can be “roughened” by subsequent drop impact and surface stresses that can produce lift/drag penalties compared to the dry, smooth aerofoil; and
d) depending on aircraft orientation, raindrops striking the aircraft unevenly impart a pitching
moment.
3.9.2 Following analysis of this hypothesis using computational hydrodynamics, the researchers
reached the following conclusions:
a) momentum penalties become significant for rainfall rates approaching 500 mm/h (extremely heavy rain); and
b) lift/drag penalties could be very significant for rainfall rates exceeding 100 mm/h (heavy rain).
3.9.3 Aircraft landing simulations indicate that a 400 mm/h rainfall rate encountered on the approach
may produce an aircraft performance deterioration equivalent to a wind shear of 18 km/h per 30 m (9 kt/100 ft). In addition, the combination of some or all of the foregoing effects could temporarily raise the stalling speed of the aircraft, possibly above the speed at which the stall warning system (stick shaker) would normally operate. Although the magnitude of the effect of heavy rain on aircraft performance has not been established, the United States Committee on Low-Altitude Wind Shear and its Hazard to Aviation recommends that investigations continue (see Appendix 2).
3.9.4 Aside from the ongoing debate regarding the aerodynamic penalties of heavy rain, there have
been cases where aircraft have penetrated severe thunderstorms and have experienced a total loss of thrust from all engines. An example is the DC-9 that crashed in 1977 while making an emergency landing after losing all-engine power in flight; the United States National Transport Safety Board (NTSB) attributed this to the direct ingestion of massive amounts of water and/or hail in a severe thunderstorm which, in combination
with thrust lever movement, induced severe stalling and major damage to the engine compressors.69
Research is also being undertaken to assess if the angle-of-attack sensor vanes used for stall warning, the wind shear warning systems and the transmission/reception characteristics of the weather radar radome could be affected by rain. It has been suggested that errors could be caused by the sensor vanes aligning partially with the angle of approaching rain, which at normal aircraft approach speeds is likely to be around 8 degrees from the horizontal.
References
1. Stewart,1979: The atmospheric boundary layer, Third IMO lecture, WMO No. 523.
2. WMO Technical Note No. 93, 1969: Vertical wind shear in the lower layers of the atmosphere.
3. Ellis and Keenan, 1978: Development of wind shear models and determination of wind shear hazards, FAA Report No. FAA-RD-79-119.
4. André and Mahot, 1982: The nocturnal surface inversion and influence of clear air radiative cooling, Journal of the
Atmospheric Sciences.
5. Heald and Mahot, 1981: The dependence of boundary layer shear on diurnal variation of stability, Journal of the
Atmospheric Sciences.
6. Abele, 1982: Diurnal variability of wind velocity increase with height, Los Alamos National Laboratory Research Paper No. LA-9601-MS.
7. Pettersson, 1956: Convective clouds and weather, Weather Analysis and Forecasting, Volume 1, 2nd Edition, McGraw Hill.
8. Cole, Allan and Miller, 2000: Vertical wind shear near airports as an aviation hazard, Preprints, Ninth Conference on
Aviation, Range, and Aerospace Meteorology, Orlando, Florida, American Meteorological Society.
9. Cole, Evans and Rhoda, 1997: Delay reduction due to the integrated terminal weather system (ITWS), terminal winds product, Preprints, Seventh Conference on Aviation, Range, and Aerospace Meteorology, Long Beach, California, American Meteorological Society.
10. Joffre, 1984: Power laws and the empirical representation of velocity and directional shear, Journal of Applied
Meteorology, Vol. 23, Issue 8.
11. Brooks, 1970: Preliminary study of wind shear in the boundary layer at Melbourne Airport, Meteorology Study No.19, Australian Bureau of Meteorology.
12. Saissac, et al., 1971: Étude dynamique de la couche 0–100 m, Monographe No. 81 de la Météorologie Nationale, France.
13. McKinley, 1984: Evaluating wind flow around buildings on heliport placement, FAA Report V85-21881. 14. Morrison, 1982: Refresher course, wind shear, Canadian Aviation.
15. Bedard and LeFebvre, 1983: Downslope windstorms and negative buoyancy forces, Preprints, 13th Conference on
Severe Local Storms, Tulsa, Oklahoma, American Meteorological Society.
16. Alaka, 1958: Aviation aspects of mountain waves, WMO Technical Note No. 18. 17. Zipser and Bedard, 1982: Front range windstorms revisited, Weatherwise, United States.
18. Smith, Crook and Roff, 1982: The morning glory: An extraordinary undular bore, Quarterly Journal of the Royal
Meteorological Society.
19. Smith and Goodfield, 1981: The 1979 morning glory expedition, Weather, London.
21. Christie and Muirhead, 1983: Solitary waves: A hazard to aircraft operating at low altitudes, Australian
Meteorological Magazine.
22. Richwien and McLeod, 1978: Low level frontal wind shear forecast test, FAA Report No. FAA-RD-77-184. 23. Badner, 1979: Low-level wind shear: A critical review, NOAA Technical Memorandum No. NWS FCST-23.
24. Wei-Kuo Tao and Simpson, 1984: Cloud interactions and merging: Numerical simulations, Journal of the
Atmospheric Sciences.
25. Byers and Braham, 1949: The thunderstorm, United States Government Printing Office. 26. Weisman, 1983: An eye to the clouds, Weatherwise, United States.
27. Peterson, 1984: A triple Doppler radar analysis of a discretely propagating multicell convective storm, Journal of the
Atmospheric Sciences.
28. Bennets, McCallum and Grant, 1986: Cumulonimbus clouds: an introductory review, Meteorological Magazine, Volume 115, Meteorological Office, London.
29. Rotunno and Klemp, 1985: On the rotation and propagation of simulated supercell thunderstorms, Journal of the
Atmospheric Sciences.
30. Davies-Jones, 1984: The origin of updraft rotation in supercell storms, Journal of the Atmospheric Sciences.
31. Vasiloff, Brandes and Davies-Jones, 1986: An investigation of the transition from multicell to supercell storms,
Journal of Climate and Applied Meteorology.
32. Srivastava, 1985: A simple model of evaporatively driven downdraft: Application to microburst, Journal of the
Atmospheric Sciences.
33. Seitter, 1983: Numerical simulation of thunderstorm gust fronts, United States Air Force Geophysics Laboratory, Environmental Research Paper No. 862.
34. Moncrieff, 1986: Comments on nor-wester thunderstorm structure, Weather, Royal Meteorological Society, London. 35. Joseph, Raipal and Deka, 1980: Andhi, the convective dust storm of northwest India, Mausam, Volume 31, Indian
Meteorological Department.
36. Fujita, 1976: Spearhead echo and downburst near the approach end of a JFK Airport runway, New York City, University of Chicago, SMRP Research Paper No. 137.
37. Wolfson, 1983: Doppler radar observations of an Oklahoma downburst, Preprints, Twenty-first Conference on
Radar Meteorology, Edmonton, Canada, American Meteorological Society.
38. Fujita, 1978: Manual of downburst identification for Project NIMROD, University of Chicago, SMRP Research Paper No. 156.
39. McCarthy and Wilson, 1982: The Joint Airport Studies (JAWS) Project, Bulletin of the American Meteorological
Society.
40. Fujita and Wakimoto, 1983: Microburst in JAWS depicted by Doppler radars, PAM and aerial photographs,
41. Wilson and Roberts, 1983: Evaluation of Doppler radar for airport wind shear detection, Preprints, Twenty-first
Conference on Radar Meteorology, Edmonton, Canada, American Meteorological Society.
42. Woodfield and Vaughan, 1983: Airspeed and wind measurements with an airborne CO2 CW laser, Royal Aircraft
Establishment Technical Memorandum.
43. Fujita and Smith, 1985: from Fujita’s “The Downburst” SMRP Research Paper No. 210, University of Chicago. 44. Wilson, Roberts, Kessinger and McCarthy, 1984: Microburst wind structure and evaluation of Doppler radar for
airport wind shear detection, Journal of Climate and Applied Meteorology.
45. McCarthy and Wilson, 1985: The CLAWS project, Preprints, Second Conference on Aviation Weather Systems, Montréal, Canada, American Meteorological Society.
46. Stevenson, 1985: The Stapleton microburst advisory service project: The operational viewpoint, United States Department of Transportation, Report No. DOT/FAA/PM-85/21.
47. Fujita, 1981: Tornadoes and downbursts in the context of generalized planetary scales, Journal of the Atmospheric
Sciences.
48. Snow, 1984: The tornado, Scientific American.
49. Snow and Pauley, 1984: On the thermodynamic method for estimating maximum tornado wind speeds, Journal of
Climate and Applied Meteorology.
50. Wolde-Tinsae, Porter and McKeown, 1985: Windspeed analysis of tornadoes based on structural damage. Journal
of Climate and Applied Meteorology.
51. Simpson, et al., 1986: Observations and mechanisms of GATE waterspouts, Journal of the Atmospheric Sciences. 52. Browning and Foote, 1976: Airflow, and hail growth in supercell storms, Quarterly Journal of the Royal
Meteorological Society, London.
53. Thorpe, 1981: Thunderstorm dynamics: A challenge to the physicist, Weather, Royal Meteorological Society, London.
54. Ellrod, 1985: Indicators of high altitude non-convective turbulence observed in satellite images, Preprints, Second
Conference on Aviation Weather Systems, Montréal, Canada, American Meteorological Society.
55. World Meteorological Organization, 1953: World distribution of thunderstorm days, Part 2, WMO Publication No. 21, Geneva, Switzerland.
56. Court and Griffiths, 1982: Thunderstorm Climatology, Volume 2, National Oceanic and Atmospheric Administration, United States Department of Commerce.
57. Easterling and Robinson, 1985: The diurnal variation of thunderstorm activity in the United States, Journal of
Climate and Applied Meteorology.
58. McCarthy and Wilson, 1984: The microburst as a hazard to aviation, 2nd International Nowcasting Symposium, Norrk`ping, Sweden.
59. Grazulis and Abbey, 1983: 103 years of violent tornadoes, 13th Conference on Severe Local Storms, Tulsa, Oklahoma, American Meteorological Society.
60. Woodfield and Woods, 1984: World-wide experience of wind shear during 1981–82, Advisory Group for Aerospace Research and Development (AGARD), Conference Proceedings No. 347.
61. Haverdings, 1980: On the use of AIDS data for a statistical analysis of wind shear during the approach, Netherlands National Aerospace Laboratory, Report NLR MP 80008 U.
62. Haverdings, 1981: AIDS-derived wind shear statistics for approach and landing, Netherlands National Aerospace Laboratory, Report NLR TR 81066L.
63. Haverdings, 1984: Wind shear investigation programme at the NLR (in Dutch, English summary), Netherlands National Aerospace Laboratory, Report NLR MP 84027 U.
64. Krauspe, 1984: Wind shear measurement on board an airliner, NASA Technical Memorandum NASA TM-77463. 65. United States Federal Aviation Administration, 1981: General Aviation News.
66. Woodfield, 1983: Wind shear and wake vortex research in the United Kingdom (1982), NASA Report CP-2274. 67. Cole, Dasey and Mathews, 1998: Atmospheric profiling to support adaptive wake vortex spacing of aircraft, 4th
International Symposium on Tropospheric Profiling: Needs and Technologies, Snowmass, Colorado.
68. Luers and Haines, 1981: The effect of heavy rain on wind shear attributed accidents, American Institute of Aeronautics and Astronautics, St. Louis.
69. Flight Safety Foundation, 1985, and the United States National Transport Safety Board Report No. NTSB-AAR-78-3 (1978).
4-1