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Weather related Aviation Crashes & Deaths in 2004 by Type of Operation ... But the vast majority of cases were nonfatal and mostly involved general aviation. ...
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Slide 1:Weather related Aviation Crashes & Deaths in 2004 by Type of Operation
Crashes Deaths Scheduled Airlines 1 13 Air Taxi, Commuter 12 29 General Aviation 98 198 Totals 111 240
Slide 2:Boeing Field
Research by NCAR and collaborators in the 1980s uncovered the deadly one-two punch of microbursts: aircraft level off when they encounter headwinds, then find themselves pushed to the ground by intense downdrafts and tailwinds.Slide 7:Wet microburst photo taken by Bill Bunting. A series of three sides. Downburst Hazards. Downburst winds can exceed 100 mph and are capable of doing the same damage as a weak to strong tornado. Rapidly shifting wind direction and changes in visibility pose problems to mobile spotters. Wet microburst photo taken by Bill Bunting. A series of three sides. Downburst Hazards. Downburst winds can exceed 100 mph and are capable of doing the same damage as a weak to strong tornado. Rapidly shifting wind direction and changes in visibility pose problems to mobile spotters.
Slide 9:Strongest winds occur in the curl. Heavy rains and flooding are likely when you see something like this. Don’t drive your vehicle into something like this.Strongest winds occur in the curl. Heavy rains and flooding are likely when you see something like this. Don’t drive your vehicle into something like this.
Slide 13:Downbursts most dangerous to aviation
On take off On landing
Slide 14: The following are some fatal crashes that have been attributed to windshear/ microbursts in the vicinity of airports: Eastern Airlines Flight 66 Pan Am Flight 759 Delta Airlines Flight 191 USAir Flight 1016
Eastern Air Lines 66 June 24, 1975 New York – Kennedy Airport 112 killed 12 injured Crashed while landing Boeing 727 Pan Am 759 July 9, 1982 New Orleans Airport 145 passenger/crew killed 8 on ground killed Crashed after takeoff Boeing 727 Flight trajectory (red line), winds (green arrows), and indicated airspeed of PAA 759 Delta 191 August 2, 1985 Dallas-Fort Worth Airport Crashed on landing 8 of 11 crew members and 128 of the 152 passengers killed, 1 person on ground killed Lockheed L-1011 USAir 1016 July 2, 1994 Charlotte/Douglas Airport Crashed on landing 37 killed 25 injured McDonnell Douglas DC-9 Downbursts Microburst Dry Microburst Damaging winds less than 2.5 miles in diameter Accompanied by little or no rainfall Wet Microburst Damaging winds less than 2.5 miles in diameter Accompanied by very heavy rainfall and perhaps hail August 1, 1983 the strongest microburst recorded at an airport was observed at Andrews Air Force Base in Washington DC. The wind speeds may have exceeded 150 mph in this microburst. The peak gust was recorded at 211 PM – 7 minutes after Air Force One, with the President on board, landed on the same runway. During take-offs the pilot experiences a headwind and increased aircraft performance followed by a short period of decreased headwind a downdraft and finally a strong tailwind During landings the airplane begins the descent flying into a strong headwind a downdraft and finally a strong tailwind represents the extreme situation just prior to impactSlide 24:Downbursts can be Divided into Two Main Types
MACROBURST: A large downburst with its outburst winds extending greater than 2.5 miles horizontal dimension. Damaging winds, lasting 5 to 30 minutes, could be as high as 134 mph. MICROBURST: A small downburst with its outburst, damaging winds extending 2.5 miles or less. In spite of its small horizontal scale, an intense microburst could induce damaging winds as high as 168 mph.
Wisconsin on the 4th of July, 1977, with winds that were estimated to exceed 115 mph, and completely flattening thousands of acres of forest Macroburst Microburst The Terminal Doppler Weather Radar (TDWR) is now deployed at 44 major airports. The TDWR mission is to provide wind shear detection services to air traffic controllers and supervisorsSlide 27:Low Level Windshear Alert System (LLWAS)
Slide 28:LLWAS
In 1983, the FAA asked NCAR to develop a version of LLWAS that could detect microbursts. Between 1983 and 1988, NCAR developed and tested a new LLWAS system, called enhanced LLWAS or LLWAS-Network Expansion that detected microbursts, determined the strength in terms of headwind/tailwind gains or losses (in knots) and located the event (on the runway, at 1, 2, or 3 nm on departure or arrival). The system was designed to provide alerts specific to each runway operation. It was designed to have a probability of detection of 90 percent or greater and a false alarm rate of 10 percent or less. This system was later improved and is now called the Phase-3 LLWAS. A typical Phase-3 LLWAS will have enough sensors to be spaced 2-km apart (~1 nm apart) and cover out to 2 nm from the end of each major runway. The largest LLWAS is at Denver International Airport. It has 32 wind sensors. Most Phase-3 systems have between 12 and 16 wind sensors. A siting evaluation is done for each airport to determine the network geometry since it depends on terrain, # of runways, obstructions, etc.
Slide 30: Microburst “Season & Time”
The four best known downburst aviation disasters in the U.S. happened in the summer. (1 in June, 2 in July, 1 in August) All four happened in the late afternoon or early evening (from 4:05 to 7:43 local time)
Slide 31:Still not There
The threat of wind shear has been reduced but not eliminated. It was mentioned in an average of 25 National Transportation Safety Board accident and incident reports a year from 1983 through 2001. But the vast majority of cases were nonfatal and mostly involved general aviation.
