Comprehensive Aviation Weather Guide

Aviation Weather Guide Part 1

Complete Guide to Aviation Weather: Understanding METARs, TAFs, and Flight Planning

Weather remains the most critical factor in aviation safety. Understanding meteorological reports, forecasts, and their practical application ensures safe flight operations whether you’re a student pilot, commercial operator, or aviation enthusiast planning a trip.

Understanding METAR Reports

METAR (Meteorological Aerodrome Report) provides current surface weather observations from airports worldwide. These standardized reports follow a specific format that pilots must learn to decode quickly and accurately.

METAR Components Explained

A typical METAR begins with the station identifier, a four-letter ICAO code identifying the reporting location. United States stations begin with K, Canadian stations with C, and so forth. The time group follows in Zulu (UTC) format, showing when the observation was taken.

Wind information appears next, showing direction in degrees true and speed in knots. Variable winds, gusts, and calm conditions each have specific notation. For example, 27015G25KT indicates wind from 270 degrees at 15 knots gusting to 25 knots.

Visibility reports use statute miles in the United States. Values less than three miles require special VFR or IFR operations. Runway visual range may supplement prevailing visibility when conditions warrant.

Present weather uses standard abbreviations. RA indicates rain, SN snow, FG fog, BR mist, and HZ haze. Intensity modifiers show light (-), moderate (no symbol), or heavy (+) precipitation. Descriptors like TS (thunderstorm) or SH (showers) provide additional detail.

Sky condition describes cloud coverage using specific terms. SKC or CLR indicates clear skies. FEW represents 1-2 eighths coverage, SCT (scattered) 3-4 eighths, BKN (broken) 5-7 eighths, and OVC (overcast) complete coverage. Heights appear in hundreds of feet AGL.

Terminal Aerodrome Forecasts

TAFs provide weather forecasts for specific airports, typically covering 24 to 30 hours. Understanding TAF structure helps pilots plan flights and anticipate changing conditions.

TAF Format and Timing

TAF validity periods appear as a date-time group showing the forecast’s beginning and ending times. The FM (from) group indicates significant changes expected at specific times. TEMPO describes temporary fluctuations, while PROB indicates probability of conditions occurring.

BECMG (becoming) groups show gradual transitions between conditions. These changes typically occur over a two-hour period centered on the specified time. Understanding these transition periods helps pilots time departures optimally.

Weather Hazards for Aviation

Thunderstorms

Thunderstorms present multiple hazards including severe turbulence, lightning, hail, heavy precipitation, and microbursts. Convective activity develops when unstable air rises rapidly, and mature thunderstorms can extend above 50,000 feet. Never attempt to fly through or under thunderstorms.

Microbursts deserve special attention. These intense downdrafts can cause rapid airspeed changes exceeding aircraft performance capabilities. Wind shear alerts at airports indicate potential microburst activity, and pilots should delay operations when these alerts are active.

Icing Conditions

Structural icing accumulates on aircraft surfaces when flying through visible moisture at temperatures below freezing. Clear ice forms in freezing rain, while rime ice develops in cloud droplets. Mixed icing combines characteristics of both types.

Ice accumulation degrades aircraft performance by increasing weight, reducing lift, and increasing drag. Anti-ice and de-ice systems protect certified aircraft, but pilots must understand their limitations and activate systems appropriately.

Low Visibility Operations

Fog, haze, smoke, and precipitation all reduce visibility. Radiation fog forms on clear nights when ground cooling causes moisture to condense. Advection fog develops when warm, moist air moves over cooler surfaces. Both types can reduce visibility below minimums rapidly.

Preflight Weather Briefings

Thorough weather briefings before every flight ensure pilots have current information for safe operations. Standard briefings include synopsis, current conditions, forecasts, winds aloft, NOTAMs, and ATC delays.

Sources of Weather Information

Flight Service provides official briefings by phone or online. Aviation weather websites aggregate data from multiple sources. Mobile applications provide convenient access to current conditions and forecasts. Regardless of source, pilots bear responsibility for obtaining and understanding weather information.

Go/No-Go Decisions

Personal minimums help pilots make consistent go/no-go decisions. These self-imposed limits should exceed regulatory requirements, especially for less experienced pilots. Factors including ceiling, visibility, winds, and pilot currency all influence these decisions.

When conditions are marginal, consider alternatives. Delaying departure, choosing alternate routes, or canceling flights entirely are all valid options. The goal is completing every flight safely, not completing every planned flight.

En Route Weather Considerations

Weather changes during flight require ongoing monitoring and flexibility. Flight Watch and Flight Service provide updates, while ATC can relay pilot reports and suggest routing around weather.

Pilot reports (PIREPs) share actual conditions encountered in flight. Contributing PIREPs helps other pilots and improves weather forecasting. Report significant weather, turbulence, icing, and any conditions differing from forecasts.

Conclusion

Weather knowledge separates competent pilots from those who merely hold certificates. Continuous learning, conservative decision-making, and respect for meteorological hazards ensure long flying careers. When in doubt, wait it out.

Part 2: Advanced Topics

Complete Guide to Aviation Weather: Understanding METARs, TAFs, and Flight Planning

Weather remains the most critical factor in aviation safety. Understanding meteorological reports, forecasts, and their practical application ensures safe flight operations whether you’re a student pilot, commercial operator, or aviation enthusiast planning a trip.

Understanding METAR Reports

METAR (Meteorological Aerodrome Report) provides current surface weather observations from airports worldwide. These standardized reports follow a specific format that pilots must learn to decode quickly and accurately.

METAR Components Explained

A typical METAR begins with the station identifier, a four-letter ICAO code identifying the reporting location. United States stations begin with K, Canadian stations with C, and so forth. The time group follows in Zulu (UTC) format, showing when the observation was taken.

Wind information appears next, showing direction in degrees true and speed in knots. Variable winds, gusts, and calm conditions each have specific notation. For example, 27015G25KT indicates wind from 270 degrees at 15 knots gusting to 25 knots.

Visibility reports use statute miles in the United States. Values less than three miles require special VFR or IFR operations. Runway visual range may supplement prevailing visibility when conditions warrant.

Present weather uses standard abbreviations. RA indicates rain, SN snow, FG fog, BR mist, and HZ haze. Intensity modifiers show light (-), moderate (no symbol), or heavy (+) precipitation. Descriptors like TS (thunderstorm) or SH (showers) provide additional detail.

Sky condition describes cloud coverage using specific terms. SKC or CLR indicates clear skies. FEW represents 1-2 eighths coverage, SCT (scattered) 3-4 eighths, BKN (broken) 5-7 eighths, and OVC (overcast) complete coverage. Heights appear in hundreds of feet AGL.

Terminal Aerodrome Forecasts

TAFs provide weather forecasts for specific airports, typically covering 24 to 30 hours. Understanding TAF structure helps pilots plan flights and anticipate changing conditions.

TAF Format and Timing

TAF validity periods appear as a date-time group showing the forecast’s beginning and ending times. The FM (from) group indicates significant changes expected at specific times. TEMPO describes temporary fluctuations, while PROB indicates probability of conditions occurring.

BECMG (becoming) groups show gradual transitions between conditions. These changes typically occur over a two-hour period centered on the specified time. Understanding these transition periods helps pilots time departures optimally.

Weather Hazards for Aviation

Thunderstorms

Thunderstorms present multiple hazards including severe turbulence, lightning, hail, heavy precipitation, and microbursts. Convective activity develops when unstable air rises rapidly, and mature thunderstorms can extend above 50,000 feet. Never attempt to fly through or under thunderstorms.

Microbursts deserve special attention. These intense downdrafts can cause rapid airspeed changes exceeding aircraft performance capabilities. Wind shear alerts at airports indicate potential microburst activity, and pilots should delay operations when these alerts are active.

Icing Conditions

Structural icing accumulates on aircraft surfaces when flying through visible moisture at temperatures below freezing. Clear ice forms in freezing rain, while rime ice develops in cloud droplets. Mixed icing combines characteristics of both types.

Ice accumulation degrades aircraft performance by increasing weight, reducing lift, and increasing drag. Anti-ice and de-ice systems protect certified aircraft, but pilots must understand their limitations and activate systems appropriately.

Low Visibility Operations

Fog, haze, smoke, and precipitation all reduce visibility. Radiation fog forms on clear nights when ground cooling causes moisture to condense. Advection fog develops when warm, moist air moves over cooler surfaces. Both types can reduce visibility below minimums rapidly.

Preflight Weather Briefings

Thorough weather briefings before every flight ensure pilots have current information for safe operations. Standard briefings include synopsis, current conditions, forecasts, winds aloft, NOTAMs, and ATC delays.

Sources of Weather Information

Flight Service provides official briefings by phone or online. Aviation weather websites aggregate data from multiple sources. Mobile applications provide convenient access to current conditions and forecasts. Regardless of source, pilots bear responsibility for obtaining and understanding weather information.

Go/No-Go Decisions

Personal minimums help pilots make consistent go/no-go decisions. These self-imposed limits should exceed regulatory requirements, especially for less experienced pilots. Factors including ceiling, visibility, winds, and pilot currency all influence these decisions.

When conditions are marginal, consider alternatives. Delaying departure, choosing alternate routes, or canceling flights entirely are all valid options. The goal is completing every flight safely, not completing every planned flight.

En Route Weather Considerations

Weather changes during flight require ongoing monitoring and flexibility. Flight Watch and Flight Service provide updates, while ATC can relay pilot reports and suggest routing around weather.

Pilot reports (PIREPs) share actual conditions encountered in flight. Contributing PIREPs helps other pilots and improves weather forecasting. Report significant weather, turbulence, icing, and any conditions differing from forecasts.

Conclusion

Weather knowledge separates competent pilots from those who merely hold certificates. Continuous learning, conservative decision-making, and respect for meteorological hazards ensure long flying careers. When in doubt, wait it out.