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Would You Go? MVFR Conditions With A Chance For Icing

Making go/no-go decisions isn't always easy, especially when it comes to cold weather and IFR flying. Take a look at this scenario, make your decision, and tell us what you'd do by emailing us at

Let's get started.../p>

Swayne Martin

Your Scenario

It's a cold fall morning in Houghton, MI (KCMX), on the Upper Peninsula of Michigan, and you're planning to fly your Cessna 182 to Eau Claire, WI (KEAU). You're an instrument rated private pilot and your C182 is fully capable of IFR flights. Normally you'd choose to fly on an instrument flight plan considering there are IFR and MVFR conditions along your route of flight.

The problem is your C182 isn't equipped for icing conditions. Now that cold weather is here, the freezing level extends all the way down to the surface (the temperature for departure is 27 degrees F, -3 degrees C). While there's a small AIRMET for IFR conditions, there's no AIRMET published in your area for icing conditions.

Looking at the map below, pink dots indicate LIFR conditions, red dots indicate IFR conditions, blue dots indicate MVFR conditions, and green dots indicate VFR conditions.


Enroute Weather Conditions

This 186 NM flight has relatively good weather. There's no precipitation reported, no AIRMET or SIGMET for icing, and clear skies on the back-half of your route. However, you still have a few challenges to deal with. Here are the conditions:

  • KCMX (Departure): KCMX 011513Z AUTO 36008KT 10SM OVC015 M03/M07 A3009 RMK AO2 T10281072
  • D25 (1/3 Enroute Point): KD25 011515Z AUTO 05005KT 10SM OVC010 M06/M08 A3007 RMK AO2 T10611085
  • KPBH (2/3 Enroute Point): KPBH 011515Z AUTO 06004KT 10SM OVC006 M09/M09 A3008 RMK AO2 T10871090
  • KEAU (Destination): KEAU 011456Z 00000KT 10SM CLR M08/M10 A3013 RMK AO2 SLP220

The picture below shows airports reporting ceilings below 3,000' AGL. If there's no ceiling labeled, the airport has ceilings greater than 3,000' or it doesn't report weather.


Most of the low weather conditions seem to be isolated around the mid-point of your route, in a 60-mile-wide cluster. To the East/Southeast, you'll find clear skies, as shown in the satellite imagery below. Avoiding the lowest weather means filing a plan with a waypoint at the Y55 airport.


Here's what the same route looks like under IFR using a nearby fix to Y55, HUKAS:


Enroute Icing Conditions

After years of lobbying from AOPA, the FAA released a revised definition in 2009 letter of interpretation that left much of the decision-making related to icing conditions up to individual pilots. No longer was there a humidity value to determine known icing conditions. The pilot's analysis of available weather products and forecasts in comparison to flight route, altitude, and time would now determine whether a flight was safe and legal. It goes without saying, but it's incredibly important that your icing knowledge is up-to-date, so you can make safe and informed pre-flight decisions. But that doesn't mean you can go flying through anything you'd like. The FAA says that in the event of an investigation...

"The FAA will specifically evaluate all weather information available to the pilot and determine whether the pilot's pre-flight planning took into account the possibility of ice formation, alternative courses of action to avoid flight into known icing conditions and, if ice actually formed on the aircraft, what steps were taken by the pilot to exit those conditions."

The following image shows the probability of icing at 3,000 feet MSL. You'll either fly through 3,000 feet to reach cruising altitude, or you might be cruising right around this altitude. As you can see, the icing conditions along your route mimic the AIRMET for IFR conditions. To the East/Southeast of your route, you won't find a high probability of icing conditions.


Do You Need An Alternate?

If the weather at your destination isn't at least 3 SM of visibility and 2000' AGL ceilings from 1 hour before to 1 hour after your ETA, you need to file an alternate. If you choose to file IFR, you don't need an alternate today. KEAU blows the 3-2-1 rule out of the water with a beautiful single line VMC TAF... A great sign that you'll have calm, clear VFR conditions for the whole day at your destination.

Under IFR (day or night), you'll need enough fuel to fly to your intended destination, fly from the destination to the alternate (if required), and fly for an additional 45 minutes at normal cruise speed (minimum).


IFR, VFR, Or No-Go: What Would You Do?

If you choose to fly, you'll likely be filing a slightly longer route around the Southeast of the IFR conditions at your enroute mid-point. That adds an extra 30-40 miles to your route. If you fly IFR, there's a chance you could encounter icing conditions on your initial climb through the clouds. If you fly VFR, you'll be scud-running for a little while until you encounter clear skies.

So what's your plan? Send us your decision-making thoughts to or leave your comment below.

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