Complete Guide to Filing Pilot Reports (PIREPs)

1. Understanding PIREPs and Their Importance

Pilot Reports (PIREPs) are real-time weather observations provided by pilots in flight, offering crucial information that supplements ground-based weather stations and forecasting models. Unlike METAR reports which provide surface conditions, PIREPs deliver airborne observations that can reveal significant weather phenomena affecting flight operations.

PIREPs serve multiple critical functions in aviation safety. They validate or correct weather forecasts, alert other pilots to unexpected conditions, and provide Flight Service Stations and Air Traffic Control with current airborne weather information. Your PIREP could be the difference between another pilot encountering dangerous conditions unprepared or making an informed decision to avoid or prepare for challenging weather.

The Federal Aviation Administration actively encourages PIREP filing, especially for significant weather conditions. These reports become part of the national weather database and are disseminated to other pilots, meteorologists, and air traffic facilities within minutes of filing.

2. When and Why to File PIREPs

The key to effective PIREP filing is understanding when your observations provide the most value to the aviation community. You should file PIREPs whenever you encounter conditions that differ significantly from forecasts or when experiencing weather phenomena that could affect other aircraft operations.

Mandatory PIREP situations include:

• Any structural or moderate-to-severe icing conditions
• Moderate or greater turbulence
• Wind shear encounters
• Volcanic ash encounters
• Unforecast weather conditions significantly different from what was briefed

Highly valuable PIREPs include:

• Cloud tops and bases, especially when different from forecasts
• Visibility conditions and flight category changes
• Temperature variations affecting density altitude calculations
• Precipitation type and intensity
• Smooth conditions when turbulence was forecast
• Surface wind conditions during approach and landing

3. Essential PIREP Elements and Format

Effective PIREPs follow a standardized format that ensures critical information is communicated clearly and completely. The standard PIREP contains six essential elements, easily remembered by the mnemonic "AC-TP-OV-TM-FL-TP":

1. Aircraft Type (AC): Specify your aircraft type as it affects how weather impacts performance. A Cessna 172 and a Boeing 737 will experience the same conditions very differently.

2. Time (TM): Report in UTC (Zulu time) when the observation was made. Weather conditions change rapidly, making timing crucial for other pilots.

3. Location (OV): Provide your position using navigation aids, airports, or geographic references. Be as specific as possible - "15 miles southwest of ABC VOR" rather than just "near ABC."

4. Altitude (FL): Report your altitude in feet MSL. Include whether you're climbing, descending, or level, as conditions often vary significantly with altitude changes.

5. Weather Elements: Describe the specific conditions you're experiencing using standard terminology and abbreviations.

6. Additional Information: Include any other relevant details such as outside air temperature, aircraft performance impacts, or pilot actions taken.

4. How and Where to File PIREPs

PIREPs can be filed through multiple channels, each with specific advantages depending on your flight situation and communication capabilities.

Air Traffic Control: The most common method during IFR flights. Simply request "PIREP" when checking in with a new controller or during routine communications. ATC will prompt you through the required elements and relay your report to appropriate facilities.

Flight Service Station (FSS): Contact FSS on 122.2 or appropriate frequencies. FSS specialists are trained to take comprehensive PIREPs and can provide immediate feedback on your report's value. This method works well for VFR flights or when you want to file a detailed report.

Ground-based Filing: You can file PIREPs after landing by calling 1-800-WX-BRIEF or using online systems. While not as timely, these reports still provide valuable information for forecast verification and trend analysis.

Communication Tips:

• Keep initial contact brief: "Approach, Cessna 123AB with PIREP"
• Have your information organized before keying the mic
• Use standard phraseology and abbreviations
• Be prepared to repeat information if requested

5. Reporting Specific Weather Phenomena

Different types of weather require specific reporting techniques and terminology to maximize the value of your PIREP.

Turbulence Reporting:

Use standardized intensity descriptors: Light (slight strain against seatbelts), Moderate (definite strain, difficulty walking), Severe (violent jolts, momentary loss of control), or Extreme (impossible to control aircraft). Include frequency - occasional, intermittent, or continuous. Learn more about different turbulence types to provide more specific reports.

Icing Conditions:

Report type (rime, clear, or mixed), intensity (trace, light, moderate, severe), and aircraft performance impact. Include altitude range where icing was encountered and any altitude changes that affected accumulation rates. Reference our guide on aircraft icing conditions for detailed reporting criteria.

Cloud Reporting:

Provide cloud bases and tops in feet MSL, coverage (few, scattered, broken, overcast), and type when identifiable (cumulus, stratus, cumulonimbus). Include visibility between cloud layers and any precipitation associated with cloud systems.

Visibility and Precipitation:

Report visibility in statute miles and fractions thereof. Describe precipitation type (rain, snow, sleet, hail) and intensity (light, moderate, heavy). Include any restrictions to visibility such as haze, smoke, or dust.

6. Common PIREP Filing Mistakes to Avoid

Understanding common PIREP filing errors helps ensure your reports provide maximum value while avoiding confusion or potential safety issues.

Vague Location Reporting: Avoid general references like "near Chicago" or "somewhere over Iowa." Instead, use specific navigation aids, airports, or geographic landmarks with distance and direction information.

Incorrect Time References: Always use UTC time, not local time. A PIREP filed at 1400 local time in New York (1900Z) but reported as "1400" could mislead other pilots about when conditions were observed.

Inconsistent Altitude Reporting: Report altitudes consistently in feet MSL. Mixing MSL and AGL references, or failing to specify altitude type, can create dangerous misunderstandings about where conditions exist.

Subjective vs. Objective Reporting: Report what you observe, not your interpretation. Instead of "bad weather," specify "moderate turbulence and 2-mile visibility in light rain." Objective descriptions help other pilots make informed decisions based on their aircraft capabilities and experience.

Incomplete Weather Descriptions: Provide complete information about weather phenomena. For turbulence, include intensity, frequency, and altitude range. For clouds, report bases, tops, and coverage. Incomplete reports may not provide enough information for safe decision-making.