ch 17 – weather evaluation for flight

Ch 17 – Weather Ch 17 – Weather Evaluation for FlightEvaluation for Flight

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• IntroductionIntroduction

– A fact of aviation today is that you must A fact of aviation today is that you must have a better understanding of weather have a better understanding of weather than your predecessorsthan your predecessors

– There are at least two primary reasons for There are at least two primary reasons for this.this.•First, approximately 25% of aircraft First, approximately 25% of aircraft

accidents are weather-relatedaccidents are weather-related– A weather-wise pilot is much less A weather-wise pilot is much less

likely to become a statisticlikely to become a statistic

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight

•Second, the rapid growth in the Second, the rapid growth in the aviation industry and the increasing aviation industry and the increasing automation of weather information automation of weather information places a greater burden on you to places a greater burden on you to obtain and interpret weather obtain and interpret weather information pertinent to your flightinformation pertinent to your flight


– The concept of a “self-briefing” to The concept of a “self-briefing” to augment official briefings requires that augment official briefings requires that you develop a procedure to obtain and you develop a procedure to obtain and integrate weather observations and integrate weather observations and forecasts into your preflight preparationsforecasts into your preflight preparations

– This chapter provides guidelines to help This chapter provides guidelines to help you develop a self-briefing procedureyou develop a self-briefing procedure

– That procedure is then demonstrated by That procedure is then demonstrated by applying it to an actual weather situationapplying it to an actual weather situation


– Finally, an outlook for improvements in Finally, an outlook for improvements in aviation weather observations, aviation weather observations, forecasts, products, and information forecasts, products, and information delivery is also provided.delivery is also provided.

– When you complete Chapter 17 you will When you complete Chapter 17 you will understand the process of combining a understand the process of combining a variety of weather information via an variety of weather information via an effective self-briefing procedureeffective self-briefing procedure


– You will also be aware of important You will also be aware of important future developments that will lead to future developments that will lead to significant improvements in your significant improvements in your operational application of aviation operational application of aviation weather knowledge and in-flight safetyweather knowledge and in-flight safety

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section A – Self – Briefing ProcedureSection A – Self – Briefing Procedure

– Self EvaluationSelf Evaluation– Aircraft CapabilityAircraft Capability– Flight DescriptionFlight Description

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section B – Weather – Evaluation Section B – Weather – Evaluation

ProcessProcess– OverviewOverview– Preflight EvaluationPreflight Evaluation– In-Flight EvaluationIn-Flight Evaluation

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section C – Developments in Aviation Section C – Developments in Aviation

Weather ResourcesWeather Resources– Observation SystemsObservation Systems– Weather ForecastingWeather Forecasting– Weather Information SystemsWeather Information Systems

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section A: Self – Briefing Section A: Self – Briefing

ProcedureProcedure– To improve your proficiency in To improve your proficiency in

weather evaluation, the weather evaluation, the development of a system for development of a system for processing information during flight processing information during flight planning is valuableplanning is valuable


– A flow diagram outlining this process is A flow diagram outlining this process is shown in figure 17-1shown in figure 17-1•Weather AwarenessWeather Awareness•Knowledge of available and relevant Knowledge of available and relevant

weather productsweather products•Self evaluationSelf evaluation•Aircraft CapabilityAircraft Capability


•Flight descriptionFlight description•Weather OverviewWeather Overview•Preflight Weather Evaluation (cancel, Preflight Weather Evaluation (cancel,

go, delay)go, delay)•In-flight Weather EvaluationIn-flight Weather Evaluation•No change – proceed to destinationNo change – proceed to destination•Divert – AlternateDivert – Alternate


– Is your meteorological training Is your meteorological training adequate?adequate?

– Are you familiar with relevant weather Are you familiar with relevant weather products and their sources?products and their sources?

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Self EvaluationSelf Evaluation

– Are you current to flying in the weather Are you current to flying in the weather conditions of the proposed flight?conditions of the proposed flight?

– Is your weather knowledge currentIs your weather knowledge current– Are you up-to-date on the latest weather Are you up-to-date on the latest weather

resources?resources?

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Aircraft CapabilityAircraft Capability

– A complete understanding of your aircraft’s A complete understanding of your aircraft’s performance capability and limitations is performance capability and limitations is essential in evaluating the weather’s impactessential in evaluating the weather’s impact

– The equipment onboard your aircraft is another The equipment onboard your aircraft is another factor to consider when assessing aircraft factor to consider when assessing aircraft capabilities capabilities

– Based on a complete assessment of yourself Based on a complete assessment of yourself and your aircraft you can set specific weather and your aircraft you can set specific weather restrictions for your flightsrestrictions for your flights

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Flight DescriptionFlight Description

– The next step in the self-briefing process The next step in the self-briefing process is to establish a complete flight is to establish a complete flight descriptiondescription

– Figure 17-2; a flight plan form can be Figure 17-2; a flight plan form can be used as a reference for the flight used as a reference for the flight description items supplied to a brieferdescription items supplied to a briefer

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• ***When you request a briefing, ***When you request a briefing,

identify yourself as a pilot and supply identify yourself as a pilot and supply the briefer with the following the briefer with the following information: information: – type of flight planned (VFR or IFR)type of flight planned (VFR or IFR)– aircraft number or pilot’s nameaircraft number or pilot’s name– aircraft typeaircraft type


– departure airportdeparture airport– route of flightroute of flight– DestinationDestination– flight altitude(s)flight altitude(s)– estimated time of departure and estimated time of departure and

estimated time en-route or estimated time en-route or estimated time of arrivalestimated time of arrival

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section B: Weather Evaluation Section B: Weather Evaluation

ProcessProcess– Once the initial steps of the self-Once the initial steps of the self-

briefing procedure are complete, briefing procedure are complete, the analysis of weather for a the analysis of weather for a specific flight can beginspecific flight can begin

– Your misinterpretation of a critical Your misinterpretation of a critical piece of weather information is a piece of weather information is a pilot errorpilot error


– Misinterpretations of weather Misinterpretations of weather observations and forecasts are observations and forecasts are usually due to not knowing one or usually due to not knowing one or more of the following:more of the following:

– What is availableWhat is available– What the information meansWhat the information means– Where you can get itWhere you can get it– When it is availableWhen it is available

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• OverviewOverview

– It is worthwhile to begin assessing the general It is worthwhile to begin assessing the general weather situation a day or two before the flightweather situation a day or two before the flight

– Pay attention to weather reports and forecasts Pay attention to weather reports and forecasts on radio and televisionon radio and television

– As time goes on, details should be added to the As time goes on, details should be added to the general patternsgeneral patterns

– The Internet or an FSS outlook briefing is The Internet or an FSS outlook briefing is helpful at this pointhelpful at this point


– About 24 hours in advance of your About 24 hours in advance of your departure, ask yourself these questions:departure, ask yourself these questions:

– Where are the areas of potentially Where are the areas of potentially adverse weather currently located?adverse weather currently located?

– How have those areas been How have those areas been moving/developing in the last 24 hours or moving/developing in the last 24 hours or so?so?

– Where will those areas be at the time of Where will those areas be at the time of your flight?your flight?


– What are the specific flight hazards?What are the specific flight hazards?– Refer to the surface analysis chartsRefer to the surface analysis charts– In many weather situations, the In many weather situations, the

intensity and organization of the intensity and organization of the weather system becomes clearer when weather system becomes clearer when you examine upper air conditionsyou examine upper air conditions

– Refer to constant pressure analysis Refer to constant pressure analysis chartscharts


– Refer to low-level significant weather Refer to low-level significant weather prognostic chartsprognostic charts

– Your efficient use of weather information Your efficient use of weather information requires that you determine all of the requires that you determine all of the weather hazards significant to your weather hazards significant to your flightflight

– An outlook briefing from flight service An outlook briefing from flight service furnishes additional information at this furnishes additional information at this stagestage

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Preflight EvaluationPreflight Evaluation

– The preflight weather evaluation is The preflight weather evaluation is usually accomplished within a few hours usually accomplished within a few hours of the proposed departure time due to of the proposed departure time due to the importance of procuring the latest the importance of procuring the latest information prior to the flightinformation prior to the flight

– Graphic weather material makes it much Graphic weather material makes it much easier and faster to visualize the easier and faster to visualize the weather situationweather situation


– This includes satellite images and maps This includes satellite images and maps of various weather phenomenaof various weather phenomena

– Plotted in-flight weather advisories and Plotted in-flight weather advisories and maps showing recent PIREPs are maps showing recent PIREPs are particularly usefulparticularly useful


– One of your important tasks at this stage is to One of your important tasks at this stage is to make use of all advisories or warnings issued make use of all advisories or warnings issued for the area at the time of your flight; look at for the area at the time of your flight; look at area forecast, AIRMETS - Sierra, Tango, Zulu, area forecast, AIRMETS - Sierra, Tango, Zulu, SIGMETS, CONVECTIVE SIGMETS, surface SIGMETS, CONVECTIVE SIGMETS, surface analysis charts, weather depiction chartsanalysis charts, weather depiction charts

– To conclude the weather evaluation, you must To conclude the weather evaluation, you must make a decision based on your analysismake a decision based on your analysis

– An important component of the self-briefing An important component of the self-briefing procedure is your own weather observationprocedure is your own weather observation

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• In-Flight EvaluationIn-Flight Evaluation

– Your evaluation of the weather does not Your evaluation of the weather does not end if a go decision is madeend if a go decision is made

– The dynamic nature of weather makes The dynamic nature of weather makes in-flight weather evaluation essential to in-flight weather evaluation essential to safetysafety


– While en-route you should also use in-While en-route you should also use in-flight weather services such as recorded flight weather services such as recorded surface observations and forecasts surface observations and forecasts (TWEB, HIWAS)(TWEB, HIWAS)

– Figure 17-16; Flight Watch is a valuable Figure 17-16; Flight Watch is a valuable weather service provided by flight weather service provided by flight service stationsservice stations

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Section C: Developments in Aviation Section C: Developments in Aviation

Weather ResourcesWeather Resources– The worldwide aviation community is The worldwide aviation community is

making major changes in the way making major changes in the way weather data are gathered, processed weather data are gathered, processed and disseminatedand disseminated

– In the US, the FAA and the National In the US, the FAA and the National Weather Service are implementing plans Weather Service are implementing plans leading to an advanced and improved leading to an advanced and improved aviation weather systemaviation weather system


– This system will integrate present and This system will integrate present and pending technologies to develop higher pending technologies to develop higher resolution and more accurate resolution and more accurate observations of atmospheric variablesobservations of atmospheric variables

– Increased computer power and modeling Increased computer power and modeling capabilities will significantly enhance capabilities will significantly enhance weather analyses and forecastsweather analyses and forecasts

– Weather information will be transformed Weather information will be transformed into aviation decision aids based on into aviation decision aids based on weather variables impacting flightweather variables impacting flight

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Observation SystemsObservation Systems

– The focus of modernized weather The focus of modernized weather observation is the production of high-observation is the production of high-quality data in nearly real timequality data in nearly real time

– It is expected that there will be 1,500 It is expected that there will be 1,500 automated surface-observation stations automated surface-observation stations such as ASOS and AWOSsuch as ASOS and AWOS


– The Doppler weather radar (WSR-88D) The Doppler weather radar (WSR-88D) was deployed initially as NEXRAD and is was deployed initially as NEXRAD and is now the primary tool of the US weather now the primary tool of the US weather radar networkradar network

– Terminal Doppler weather radar (TDWR) Terminal Doppler weather radar (TDWR) has been installed at numerous large has been installed at numerous large airports in the US where thunderstorms airports in the US where thunderstorms and microbursts are most commonand microbursts are most common


– Low-level wind shear alert systems (LLWAS) Low-level wind shear alert systems (LLWAS) have been installed at 110 airports in the UShave been installed at 110 airports in the US

– The radiosonde network has been the The radiosonde network has been the primary upper-air data source for weather primary upper-air data source for weather forecasting for many yearsforecasting for many years

– The wind profiler is a vertically pointing The wind profiler is a vertically pointing microwave radar that measures horizontal microwave radar that measures horizontal wind speed and direction at 72 levels wind speed and direction at 72 levels between about 1,500 feet AGL and 53,000 between about 1,500 feet AGL and 53,000 feet MSLfeet MSL


– Another on-going development in upper-air Another on-going development in upper-air observations has been the development of observations has been the development of the international aircraft meteorological data the international aircraft meteorological data reporting (AMDAR) system using commercial reporting (AMDAR) system using commercial aircraft as observational platformsaircraft as observational platforms

– There are two primary data-gathering There are two primary data-gathering systems by AMDARsystems by AMDAR

– The first is the aircraft-to-satellite data relay The first is the aircraft-to-satellite data relay (ASDAR) system which uses specially (ASDAR) system which uses specially designed hardware that must be fitted to and designed hardware that must be fitted to and certified for the aircraft on which it is installedcertified for the aircraft on which it is installed


– The second method for the gathering of The second method for the gathering of meteorological information from aircraft meteorological information from aircraft is the aircraft communications, is the aircraft communications, addressing and reporting system addressing and reporting system (ACARS)(ACARS)

– The AMDAR (ASDAR/ACARS) system has The AMDAR (ASDAR/ACARS) system has been highly successfulbeen highly successful


– The modern weather satellite has The modern weather satellite has developed far beyond the acquisition of developed far beyond the acquisition of images of cloud patternsimages of cloud patterns

– Satellites such as the geostationary Satellites such as the geostationary operational environmental satellite operational environmental satellite (GOES) provide simultaneous imaging as (GOES) provide simultaneous imaging as well as temperature and moisture well as temperature and moisture profilesprofiles

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Weather ForecastingWeather Forecasting

– In addition to more and better meteorological In addition to more and better meteorological observations, a better understanding of observations, a better understanding of atmospheric processes, faster computers, and atmospheric processes, faster computers, and better numerical techniques are leading to better numerical techniques are leading to significant improvements in weather significant improvements in weather forecastingforecasting

– A strong US government initiative in support A strong US government initiative in support of aviation has resulted in the development of of aviation has resulted in the development of the aviation gridded forecast system (AGFS)the aviation gridded forecast system (AGFS)


– The purpose of AGFS is to use the output The purpose of AGFS is to use the output from NCEP models, such as RUC and other from NCEP models, such as RUC and other specialized computer code to generate high specialized computer code to generate high resolution Aviation Impact Variables (AIV)resolution Aviation Impact Variables (AIV)

– The Aviation Division of the NOAA Forecast The Aviation Division of the NOAA Forecast Systems Laboratory works cooperatively Systems Laboratory works cooperatively with the Aviation Weather Center (AWC) to with the Aviation Weather Center (AWC) to integrate AIVs into the aviation forecast integrate AIVs into the aviation forecast processprocess


– Other on-going efforts to improve Other on-going efforts to improve aviation weather forecasts are aimed at aviation weather forecasts are aimed at thunderstorms, ceiling and visibility thunderstorms, ceiling and visibility predictions, ground deicing, and the predictions, ground deicing, and the prediction of wake vortex behavior at air prediction of wake vortex behavior at air terminalsterminals

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• Weather Information SystemsWeather Information Systems

– Effective aviation weather information Effective aviation weather information systems must meet two important systems must meet two important requirementsrequirements

– The world area forecast system (WAFS) is a The world area forecast system (WAFS) is a satellite communications system to provide satellite communications system to provide the worldwide aviation community with the worldwide aviation community with weather information for flight planning and weather information for flight planning and to support the en-route phase of flightto support the en-route phase of flight


– In the US, the FAA’s Aviation Weather In the US, the FAA’s Aviation Weather Research (AWR) program supports a Research (AWR) program supports a research project that is addressing the research project that is addressing the need for improved weather presentationneed for improved weather presentation

– Two other significant components of the Two other significant components of the AWR program are the aviation weather AWR program are the aviation weather products generator (AWPG) and the products generator (AWPG) and the integrated terminal weather system integrated terminal weather system (ITWS)(ITWS)


– The purpose of the AWPG is to provide The purpose of the AWPG is to provide analysis and forecast products tailored analysis and forecast products tailored for the en-route phase of flightfor the en-route phase of flight

– ITWS is designed to enhance the FAA’s ITWS is designed to enhance the FAA’s ability to monitor and predict weather ability to monitor and predict weather that impacts aircraft in the vicinity of that impacts aircraft in the vicinity of the terminalthe terminal


– Input into ITWS includes LLWAS, Input into ITWS includes LLWAS, weather radar, automated weather weather radar, automated weather observations, aircraft observations and observations, aircraft observations and forecast model outputforecast model output

– By 1999, ITWS had been deployed to 34 By 1999, ITWS had been deployed to 34 locations serving 45 of the busiest locations serving 45 of the busiest airports in the USairports in the US


– In the future, the weather requirements for In the future, the weather requirements for free flight and other planned improvements free flight and other planned improvements to the national and global air navigation to the national and global air navigation systems will make rapid delivery of better systems will make rapid delivery of better weather information to the cockpit a priorityweather information to the cockpit a priority

– Beyond TWIP, the FAA is developing Beyond TWIP, the FAA is developing standards and procedures for the standards and procedures for the transmission of enhanced weather transmission of enhanced weather information directly to the cockpits of information directly to the cockpits of aircraft in all phases of flightaircraft in all phases of flight


– As these cockpit request/display As these cockpit request/display systems become a reality, concern for systems become a reality, concern for simplicity in operation and interpretation simplicity in operation and interpretation will be critical in order to reap the will be critical in order to reap the maximum safety benefits in an already maximum safety benefits in an already busy cockpitbusy cockpit

Ch 17 – Weather Evaluation for Ch 17 – Weather Evaluation for FlightFlight• SummarySummary

– The future holds exciting advancements The future holds exciting advancements in aviation weather technology including in aviation weather technology including improved observations and forecasts, improved observations and forecasts, and better access to weather products and better access to weather products that are more comprehensive, yet easier that are more comprehensive, yet easier to interpretto interpret


– In order to make the best use of these In order to make the best use of these developments for safe and enjoyable developments for safe and enjoyable flying, you must continually make an flying, you must continually make an effort to stay abreast of new systems effort to stay abreast of new systems and weather products as they become and weather products as they become operational.operational.


– Your meteorology education has only Your meteorology education has only started herestarted here

– It is a continuing processIt is a continuing process– As with flying, it is up to you to stay As with flying, it is up to you to stay

current with aviation weathercurrent with aviation weather

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