WHY PIREPs? ....

 Acknowledgements: aopa.org (TRAINING AND SAFETY/ONLINE LEARNING)

 (Ed.Note: The thought of using the radio pro-actively for anything other than responding to ATC instructions may be a bit daunting for some, particularly those at student or newly-qualified level, but the following AOPA lesson might encourage everyone to assist their fellow flyers by letting them know what they are actually experiencing during a flight .v. the available forecast information. Browse aopa.org for many other useful topics and learning materials) 

 “PIREPs are reports of actual in-flight weather conditions, created by pilots and given to flight service or ATC ... and then made available to other pilots. An accurate understanding of the weather is critical to the safety of flight. Attempting to continue visual flight into instrument conditions is consistently one of the leading killers in general aviation, but it’s far from the only hazard arising from unfriendly weather. Thunderstorms, non-convective turbulence, and both airframe and induction icing bring down airplanes every year.... PIREPs are transmitted in real time, providing information on actual:

  • Cloud tops

  • Cloud layers

  • Turbulence

  • Icing conditions

  • Visibility and precipitation

  • And more!

Pilots use this information to visualise actual in-flight weather conditions, verify forecasts, and fill in gaps between ground-based weather reporting stations .... Remember that most of the briefing information you get on cloud tops, cloud layers, turbulence, and icing conditions is only a forecast, not a report .... 

What information should be included when you give a PIREP?

The PIREP format is “who, where, when, and what.” The “who” and “when” are straightforward. For “where” use your altitude and position relative to an airport or NavAid. You can also use latitude and longitude. The “what” requires a little more thought and may include:

  • Cloud coverage and altitude

  • Flight visibility

  • Precipitation

  • Restrictions to visibility

  • Temperature

  • Wind speed and direction

  • Turbulence

  • Icing

  • Remarks given by the pilot 

Not all items are required - you can give a PIREP with only one item. It will be useful!

Reporting Visibility

There are a couple of ways to estimate visibility. 

  • Use your sectional chart/plotter to determine visibility by measuring from your current position to the most distant charted landmark you can see in front of the aircraft. 

  • Use GPS to calculate the distance from your present position to the most distant landmark you can see; or record the time it takes to get to that point and calculate the distance based on your approximate groundspeed. 

Reporting Cloud Type, Height & Coverage

If you know the cloud type, report it. The basic cloud types are: 

·       Stratus

·       Cumulus

·       Towering Cumulus

·       Cirrus

·       Cumulonimbus 

Estimating cloud height can be a little more challenging than estimating visibility. If the clouds are relatively close to your current altitude, you can add or subtract the estimated distance above or below you from what you read on the altimeter. Another method is to note how fast the clouds appear to be moving. The faster they seem to be moving, the closer they are to your altitude .... You can only describe the cloud coverage you observe in your immediate vicinity: 

·       Clear=no coverage

·       Few=>0 to 2/8 coverage

·       Scattered=3/8 to 4/8 coverage

·       Broken=5/8 to 7/8 coverage

·       Overcast=8/8 coverage

Reporting Turbulence 

·       Light: Momentary slight, erratic changes in altitude and/or attitude.

·       Light Chop: Slight, rapid, somewhat rhythmic bumpiness without appreciable change in altitude or attitude. 

·       Moderate: Changes in altitude and/or attitude occur but the aircraft remains in positive control. Usually causes variations in indicated airspeed. 

·       Moderate Chop: Causes rapid bumps or jolts without appreciable changes in altitude or attitude; unsecured objects dislodged. 

·       Severe: Large, abrupt changes in altitude and/or attitude. Usually causes large variations in indicated airspeed and the aircraft may be momentarily out of control. Occupants violently forced against their seatbelts; unsecured objects tossed throughout the cabin. 

·       Extreme: Aircraft violently tossed about and practically impossible to control; may cause structural damage. 

The terms intermittent (INTMT), continuous (CONS), and occasional (OCNL) can and should be applied to turbulence reports, too.

Reporting Ice

·       Most light GA aircraft are not certified for flight in icing conditions - for good reason! If your airplane is in this category, all you need to remember is that all ice is bad news. Outside air temperature should always be reported whenever ice is included in a PIREP. 

Icing Types and Intensities:

  • Trace: Ice becomes perceptible. Rate of accumulation slightly greater than sublimation. De-icing/anti-icing equipment not used unless encountered for an extended period of time (over one hour).

  • Light: Rate of accumulation may create a problem if flight prolonged in this environment (over one hour). Occasional use of de-icing/anti-icing equipment removes/prevents accumulation. 

  • Moderate: Rate of accumulation such that even short encounters become potentially hazardous; use of de-icing/anti-icing equipment or flight diversion necessary.

  • Severe: Rate of accumulation such that de-icing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion necessary.

Reporting Precipitation

·       The type of precipitation is usually easy to determine: Rain, Snow, or Hail

·       Remember to include the intensity level: Light, Moderate, or Heavy

.... n.b.Virga isn’t considered precipitation because it evaporates before reaching the ground. It’s included in the “Remarks” section of a PIREP.

How PIREPs Improve Forecasts 

PIREPs are used to verify or amend conditions contained in aviation forecasts and advisories. In some cases, PIREPs of hazardous conditions are the triggering mechanisms for the issuance of advisories. Flight service also cites relevant PIREPs during pilot weather briefings.

 Keep These Points in Mind

·       Don’t Worry! It’s helpful if you can give a PIREP in the proper order, but the main objective is to get the information reported. The person recording the PIREP will put it in the correct format.

  • Real-time weather. PIREPs provide critical real-time flight conditions ....

  • Review PIREPs as an essential part of your pre-flight planning

  • In-flight updates - you can get PIREPs while en-route

  • Giving a PIREP is easy (Use plain language when describing what you see)

  • Give and get. The more PIREPs we have, the better

  • Give a PIREP on every flight outside of the traffic pattern

  • Consider providing a Route PIREP to describe conditions between two or more points

  • Reports of actual weather conditions are indispensable when the weather turns out better (or worse) than forecast

  • PIREPs (including fair weather PIREPs) provide key information to improve forecasts; so, the more PIREPs we have, the better”.

 FLY SAFE!

Tony Birth