A tale of two pilot weather reports

There's no doubt there are pilot weather reports (PIREPs) that are extremely helpful and those that are not as helpful. As shown on the EZWxBrief EZMap below, here's a perfect example of two icing PIREPs to the southwest of Nashville, Tennessee just 10 miles apart; but for their utility of the icing threat, they are light years apart.

The southern PIREP from a King Air 90 (BE9L) shown below reported light light icing at 1055Z, but notice that the altitude is UNK (unknown). This is because the flight level (FL) is missing since the PIREP only indicates it was taken during the climb (FLDURC). Yes, the pilot reported bases at 4,000 feet and tops at 6,000 feet MSL which you might likely assume are the altitudes that icing was being accreted on the airframe...but you don't know for sure from this report.


BNA UA /OV 20 SW BNA/TM 1055/FLDURC/TP BE9L/SK BASES 040 TOPS 060 /TA 0/IC LT RIME


On the other hand, notice the northern PIREP from a Beech Bonanza (BE35) shown below at 1157Z that reported light rime icing as well, but the pilot went a bit further reporting that icing was accreting on the airframe from 4,000 feet to 6,300 feet MSL. That's very specific and helpful to any pilot, air traffic controller, forecaster or researcher who reads the report.


BNA UA /OV 12SW BNA/TM 1157/FL070/TP BE35/IC LT RIME 040-063


Although the second report is much better from an icing perspective, there are other improvements that could have been made by both pilots. It's critical when making a PIREP to be as specific as possible. Failure to do so may send the wrong message or just send no message at all. When climbing through a layer containing airframe ice, always try to make as specific of a report as possible...as did the Bonanza pilot. Same should be said of turbulence reports. This makes it clear what altitudes are of particular concern. Yes, this is a relatively thin cloud layer, but what if the layer were 5,000 feet thick or 7,000 feet thick? This can make a huge difference to report the actual altitudes that airframe icing (or turbulence) was experienced during the climb.


Also, both pilots reported being a distance southwest (SW) of Nashville (BNA). That gets coded as the 225° radial. If that's the right location, great. But often it's just a wag to expedite the report (i.e. too lazy to determine their exact location). It's better to provide the radial and distance (e.g., 22 miles off the BNA 245 degree radial). Lastly, the second report is definitely more useful, however, the pilot should have reported at least the height of the cloud tops.


All of this might seem like a gnat's eyelash in the grand scheme, but the PIREPs pilot's make for icing and turbulence also get ingested into the Current Icing Product (CIP) and Graphical Turbulence Guidance (GTG) product you can find in the EZWxBrief EZImagery and on the Aviation Weather Center website. So, making the best estimate of your position is important to get the location correct for these tools to properly integrate your report. Moreover, because the first pilot did not make a specific icing report it would have been tossed by the CIP algorithm whereas the second PIREP would have been used to bolster the icing situation in this area at 12Z.

Most pilots are weatherwise, but some are otherwise


Dr. Scott Dennstaedt

Weather Systems Engineer

Founder, EZWxBrief™

CFI & former NWS meteorologist

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