I recently gave a presentation at the Piper M-Class Owner’s and Pilot’s Association (PMOPA) East Coast Regional Seminar at the beautiful Greenbrier Resort in White Sulpher Springs, West Virginia on Icing. It’s that time of year in the US where Icing becomes a much more relevant topic for pilots, especially pretty much anywhere outside Texas (where I’m based). I joke with pilots from “up north” (see: Oklahoma) and tell them that we only see ice in movies, which is true with the exception of about a week out of every winter. So, this topic will still be relevant for Texan pilots, even if only for a week out of the year. Let’s hope we don’t have another Snowpocalypse this spring!
I am not going to re-hash the whole presentation here, but I do want to focus on the resources that pilots have available to them in pre-flight planning through Foreflight, Garmin Pilot, and a few other apps.
The Foreflight planning tools start on the Map page. For our scenario in this article, I am going to be using a flight plan from KLWB, Lewisburg, West Virginia, to KJAX, Jacksonville, FL using a Piper JetProp profile.
Step 1 is to select a route to file between the two airports. A Piper JetProp will want to be at FL270 as much as possible, which will give it the best TAS and lowest fuel flow, which means Class A airspace and an IFR clearance. So, I like to use the routes tile on the right hand side of the flight plan box at the top of the Map page. I picked the Foreflight suggested route of MAACK.KEGGG.MILEN.ALLMA.ALCRN1.
Once that is loaded in, I tapped the dropdown menu on the top left hand corner of the Map page and selected Icing US. Note there is a slider on the lower right hand side of the Map that allows you to select an altitude. I already looked at all the different altitudes I could go through and 17,000 feet looked the worst, so I left the slider there.
Now, I go back up to the Flight Plan bar and tap Profile. There is a separate drop down menu at the lower left hand section of the profile bar that allows different weather overlays in the profile. I selected Icing and Clouds. I also made sure that the altitude slider on the left hand side of the Profile bar was at FL270 so I could see everything I would be experiencing. As you can see, there will be light, moderate, and severe icing on our descent into KJAX.
Next, I zoom in on the icing shown on the profile box so I can see where it begins. It appears that the icing starts halfway between MILEN and ALLMA. What I want to know next is what altitude it starts at, so I move the altitude slider down on the left side of the profile box. It looks like the light icing starts at 26,500 feet, immediately after I would start my descent. I move the slider down more to see where the moderate ice starts and it’s FL240. The severe icing starts at FL210 and ends at 15,000. In total, the icing doesn’t end until 12,000 feet.
That’s 14,000 feet of ice to go through on my descent. I don’t really like the looks of that. Even at 1,000 feet per minute for a descent rate, that’s still 14 minutes of ice that will build up on my airplane, with 6,000 feet being severe (which equates to 6 minutes). Plus, keep in mind that a Piper JetProp is not rated to go into severe icing.
One thing to keep in mind is that the Profile Icing information is the forecasted information at the time we are scheduled to go through that specific area based on your ETD in your flight plan (which is really cool and innovative on Foreflight’s part).
Based on all this information, what’s the safest way to make this trip? After MILEN, start your descent and get down below 12,000 feet before 50nm prior to ALLMA. Make sure to always look at the Radar overlay on the Map page as well, since icing is not the only weather item of concern.
Other resources that the Foreflight Map can give you is Icing AIRMETs. At a quick glance, a pilot can see the forecasted levels of icing, then dig deeper into it. I don’t leave the AIRMETs turned on all the time, but I’ll tap them one at a time when looking over my route to see what’s going on. One at a time is nice so that there aren’t too many colors on the page.
The last thing to utilize on the Foreflight Map is PIREPs. PIREPs give information on what is actually happening in real time.
Please, even after doing all this analyzing, don’t forget to get an official weather briefing either on the phone (1-800-WXBRIEF) or on Foreflight on the Flights page (see picture below).
The other item that I like to use when planning cruise altitudes, getting an idea of freezing levels, cloud tops and cloud bases, is the SKEWTLOGP chart, which can be accessed on the SKEWTLOGPRO app on the iPhone or iPad. The below picture is from the iPhone app and showing the temperature graph at the AYS airport, which is halfway between ALLMA and ALCRN on our route.
The SKEWT chart graphs temperature and dew point with altitude. Whenever the temperature (red line) and dew point (blue line) are separate, there are no clouds. When they meet, there are clouds. Very simple. The white area of the graph is above freezing temps, the red diagonal line is the freezing level and the sky blue area moving to the upper left hand corner is areas below freezing.
According to the above graph, the temp and dew point meet close to 15,000 feet (which is pretty close to what Foreflight said) and separate at a little over FL200. The freezing level is about 14,000 feet (where the red temperature line hits the 0C diagonal line). So, at the AYS airport, it would be prudent to be below 14,000 feet in warm temperatures and below the bases of the clouds if we were descending into JAX.
The other cool thing with the SKEWT app is the ability to put a route in and look over points on the route to see what the temp and dew point are doing. By doing this, we can see at the RVJ airport, which is halfway between MILEN and ALLMA, the temperature and dew point barely touch around FL180, but are otherwise separated, meaning there aren’t a whole lot of clouds. The METAR for RVJ when I took this screen shot showed CLR.
Make sure you know your airplane’s de-ice system extremely well before even considering penetrating icing conditions. All Piper PA46 aircraft are only certified for flight in ice up to moderate (but please don’t stay in it for any more than a couple minutes!). Know what speeds you have to maintain in icing conditions (all aircraft have a minimum ice penetration speed so you don’t stall). I didn’t even get into SLD here, but use the Foreflight Imagery section to see what altitudes have the possibility of SLD and stay far away (that’s for another article).
And please, if you have never been in ice before, take an instructor with you the first time, have a thorough pre-flight briefing with the instructor on what the plan is, how the ice will be handled, how long the plan is to stay in ice, what to do in an icing emergency, and how the aircraft’s system works. Don’t go into ice by yourself that first time. Save the flight for another time, or land and spend the night somewhere until the ice passes. I don’t recommend landing in icing conditions for GA pilots as the speed requirement on final is much faster than normal and the flap usage is zero flaps, which is also abnormal. Don’t ever go into freezing drizzle, freezing rain, or SLD, no matter what kind of airplane you are flying.
Icing is dangerous, but don’t let your lack of knowledge and experience make it more dangerous. Learn all you can and experience it in a controlled environment before actually going in icing conditions. You can look at a website like Kathryn’s Report to see all the icing accidents that happen every year. Please don’t be another statistic.