A personal Go or No Go scenario – grade my decision

We’ve posted over 40 Go Or No Go scenarios at Air Facts, where we present a weather briefing and ask if you would make the proposed flight. All of these are based on real weather conditions, but most are not real flights we took. The point is to practice making decisions and share your thinking with other pilots.

This one is different: I was trying to fly home to Cincinnati, Ohio (LUK), from Pittsburgh, Pennsylvania (PIT), at the end of 2019, and the weather wasn’t great. The screenshots below are the actual ones I was looking at as I sat in the lobby at Atlantic Aviation in Pittsburgh, making my go/no-go decision. I’ll share the weather briefing, then ask you to add your comment about what you would do. Then, at the end, I’ll reveal what my decision was and what my thought process was.

I encourage you to think about this scenario based on the type of flying you do and the type of airplane you fly. In my case, I was flying a Pilatus PC-12, so I had good equipment: glass cockpit, datalink weather, on-board radar, and deice boots. I have about 1,000 hours in the airplane and am IFR proficient.

Overview

The goal on this day was to fly my family home after a brief visit to Pittsburgh, so while safety is always the number one priority (my standards do not change depending on the passenger), comfort was also an important consideration. Flying is supposed to be both convenient and fun for my wife and two kids. A modest headwind meant the flight was forecast to take 1 hour and 7 minutes at typical cruising altitudes (usually between 18,000 and 22,000 feet for a shorter flight). Proposed departure time was 2030Z.

The route overview in ForeFlight wasn’t too pretty, and neither was the view out the window. Rain was covering the map and there were plenty of PIREPs for icing and turbulence.

The driving force behind this messy weather was a low pressure system moving into the Great Lakes, with an attached cold front stretching all the way from Minnesota to Texas.

The prog charts showed this system marching across Indiana and Ohio, with the front slowly occluding.

Overnight, the low was forecast to strengthen and even produce areas of convective activity.

How about tomorrow? The prog charts showed the system finally moving through PIT Monday morning, but with leftover rain and winds behind the front.

Satellite and SIGMETs

The radar image above showed some yellow cells, but mostly green with a shallow gradient. There were no sharply-defined lines and no cloud-to-ground lightning symbols on the map. To me, this looked like almost all rain, with very little convection. Further west, closer to the cold front, there appeared to be some nastier stuff, but the rain over Ohio and Pennsylvania looked like classic warm front weather.

To get another look at it, I reviewed the satellite imagery. First, the infrared satellite, overlaid on my route.

Then I looked at the visible image, which didn’t show a whole lot of detail:

Another tool for determining whether rain is convective or not is the Convective SIGMET. This showed the potential for some storms to the southwest of my destination, but nothing over Ohio.

Icing

At this point I was fairly certain that this weather system didn’t contain any big thunderstorms; maybe some moderate rain, but not too much more than that. The bigger concern was in-flight icing—my route would be east of a low and along a warm front, often the area of worst icing in a large weather system. A good place to start is with the Graphical AIRMET, and sure enough, this showed lots of ice:

That’s a good overview, but it’s pretty rough. For a more detailed look, I went to the ForeFlight Maps page and the Icing forecast layer. I reviewed this at a number of different altitudes. While 20,000 feet would be typical on a flight like this, I suspected lower might be better. For one, it looked like I wouldn’t be getting on top today—even at FL220 the icing was mostly light but it was still ever-present:

At FL200 things got worse:

It was the same story at 18,000 and 16,000 feet, with solid blue all along my route (indicating moderate ice).

By 12,000 things seemed to be lightening up just a bit:

And by 10,000 it looked like we would be out of any ice:

But these maps, while really powerful, only show the severity of icing. I was also interested in the probability of icing—how likely was it that I would get that moderate ice? For that, I went to the Imagery tab in ForeFlight. These charts showed a pretty high likelihood of ice from the mid-20s on down. Here’s FL190:

At 15,000 feet, the probability was even higher:

By 11,000 feet the chance of icing was a lot lower over central Ohio, although more ice was forecast to the west of my destination:

So far it looked like a pretty high chance of moderate ice between about 12,000 and 22,000 feet. Time to back up those forecasts with some real world observations: PIREPs. There were a lot of these, but most mentioned light icing, not moderate or worse. The static chart in the Imagery tab gave me a good overview:

Next it was time to look at specific PIREPs to see how old they were, what altitudes they mentioned, and what the airplane type was. First up was a report just north of Columbus, Ohio, with light mixed icing between 17,00 and 19,000:

South of our course, a Cessna 421 reported light rime at 12,000 feet.

Just west of there, a Piper reported moderate rain and light chop at 10,000 feet, but no ice. Those negative ice PIREPs are really valuable, and far too rare—this helped me set a floor for the icing threat.

A 737 reported light icing at 23,500, suggesting that there was no topping this weather (at least in a Pilatus).

West of Dayton, Ohio, a regional jet reported light rime at 20,000 feet.

Turbulence

That lengthy review of the icing conditions suggested that I would very likely pick up some of the white stuff, but the PIREPs looked a lot less worrying than the forecast charts. Next on my list was turbulence—as I mentioned, I’m flying my family, not freight, so a good ride is always appreciated. With all that frontal activity, was this going to be a rough day to fly? The Graphical AIRMET wasn’t too encouraging, with lots of bright colors and warning about low level wind shear (LLWS).

But once again, I find this chart to be just a starting point. It doesn’t have the detail to really help me make a decision. For that, I turned on the turbulence forecast layer on the Maps page in ForeFlight. At 18,000 feet, the map was pretty encouraging—all the ugly stuff was well west of my route.

The story was the same at 16,000 feet:

And likewise at 12,000 feet, with nothing more than light:

Text Weather

So far I had spent a lot of time on en route weather, but the ceiling and visibility weren’t great either. At PIT, conditions were IFR with rain and mist, and forecast to stay that way.

At Lunken, conditions were actually quite good, with a very high ceiling and light rain. Overnight things were forecast to get windy and rainy, but not until well after my ETA:

Decision Time

Now I’d like to hear what you think. Given that weather report, would you have made this flight or canceled? Write down what you think—before you read my decision below!

 

 

 

 

What I Decided

In the end, I decided to fly. It wasn’t automatic—there was a lot of weather to consider here in any airplane—but by the time I walked through the FBO doors, I was pretty confident that we would have not just a safe flight but a pretty smooth one too. Here was my thinking:

  • I always start with the big picture, and while that showed a winter warm front and an approaching low, my route would be east of the main frontal zone. It looked to me like the cold front and occlusion were the worst weather, and I was going to miss both of those.
  • After the big picture, I always evaluate the three major weather threats: thunderstorms, icing, and low IFR conditions. These are responsible for the vast majority of weather accidents.
    • Storms: I was confident that we would fly through nothing worse than moderate rain. That can be unnerving, but it’s perfectly safe. The radar image had no unusual shapes, no bright orange or red, and no lightning. This was warm front rain, not a squall line.
    • Icing: this was probably my biggest concern. While the PC-12 is approved for flight into known icing conditions (and handles it quite well), nobody likes slogging through moderate ice. While the forecast products looked less than ideal, all the PIREPs were for light ice. Plus, I knew that I would be out of the ice by 10,000 feet (and in VFR conditions closer to home). That’s low for a Pilatus, but it gave me a solid out if things really got ugly.
    • Low IFR: I fly a lot of IFR and had a co-pilot in the right seat, so the PIT weather wasn’t much of a concern for me. It was well above approach minimums if I had to get back, and the weather at LUK was excellent.
  • After threats comes comfort: even if the flight was perfectly safe, would my passengers get beat up? On this topic, things looked surprisingly good. Both the PIREPs and the turbulence forecasts showed pretty good rides below 20,000 feet. While I don’t have screenshots of it here, the winds aloft also weren’t blowing too hard or showing much sign of shear (at least over Ohio—west of that cold front things were much more exciting).

How it went

We took off into light rain and quickly went IMC. We wouldn’t see the ground again until we descended into Cincinnati. But we had a smooth ride, with just occasional light turbulence (and not even much of that). There were some pockets of moderate rain, but nothing convective. Here’s the SiriusXM radar image on Garmin Pilot:

We started out at 16,000 feet, but about 20 minutes into the flight, we started to pick up some ice. I would call it light with a few spots of moderate. The boots were keeping up but I don’t like hanging out in ice so we went down to 14,000 feet. At that altitude we were almost completely ice-free, and by the time we were 20 miles northeast of Columbus the clouds were starting to become more layered. We made an uneventful landing in Cincinnati and had the airplane in the hangar long before the heavy rain moved in.

Some might say the weather was only going to be better tomorrow, so why not wait? That ended up being true, but only in terms of rain and ceiling. The cold front ended up being a strong one, with thunderstorms overnight, and the winds created some truly bad rides. A Monday flight would have been doable but unpleasant.

Sometimes as pilots we rationalize any decision that doesn’t kill us (“I made it, so I must have made the right decision”), but I’m happy with both my decision and my process for making it. This was worse than normal weather for me, but not dramatically so.

As always, we welcome your comments below.

19 Comments

  • The flow of your weather analysis is similar to mine: Prog charts first for the big picture, then see how that’s manifesting with radar and satellite. Next, area forecasts and TAFs for departure, destination, and en-route (area forecasts inform the TAFs, and reading the textual forecast helps me understand what’s going on). Next up, threats–each AIRMET compared to its more detailed companion (Tango–GTG; Zulu–CIP/FIP; Sierra–Clouds and Surface Forecasts) and convective SIGMETs compared to TCF/ECFP. Finally, PIREPs for real-world experiences. If anything looks like a no-go, I’ll start looking for more advantageous time windows across the forecast products.

    The factors and red-lines that form no-go decisions are personal, pilot-dependent, and aircraft dependent, but I’ve developed a regular flow to my weather self-briefing that I feel addresses those factors; I find it reassuring that you (with all your experience) use a similar structure in your self-briefing.

  • I fly a 172, and am both instrument current and proficient. With that said, I would not make the flight based on equipment and time in the soup. My instrument rating is a ticket to vfr weather, a skill builder, and a safety net. While I love flying instruments, this particular flight would be beyond my comfort, mainly due to icing concerns. Put that same warm front on the gulf coast of Alabama where I’m at, and it might be a go.

  • Go, stay low and be ready to 180

    I’d be shocked if it was this looks like a doable, routine Fiki ifr flight

    Hope I didn’t miss something!

  • The basic plan is go high with light ice or low with turbulence, and you can always trade one for the other to your liking. The crew and equipment make this flight pretty reasonable.

    I’d think hard about making the flight in a low performance AC without ice protection and need to look at the icing probability and severity below 10,000. The vertical plots of temperature and dewpoint along your intended and alternate routes (from the RUC model) are really helpful for decision making when you can’t rely on climb capability to reach a better atmosphere.

    Thanks for including the image of your wing. That light mixed ice may not look like much but I wouldn’t linger in it given the choice.

    • This was an interesting day. I think at 8000 feet in a Cirrus it would have been fine, too. No ice anywhere below 12,000 feet on this day and you would have been VMC after the first hour or so. Maybe some bumps and definitely some rain, but this was a day where the teens and low 20s were worse than lower altitude.

      I don’t fly the Cirrus as much as the PC-12, but I was thinking whether I would have made the trip in it. Not sure, but my hesitation is more down to my lack of experience in the airplane.

  • John – we were in Florida that same weekend, planning on heading north to KITH the following Wed. I was already watching the weather march across the country, clearly recalling the prog charts you show and happy that it would be later in the week when most (not all) of the weather would depart.

    It’s interesting that our Aerostar and the Pilatus have somewhat similar operating profiles (the PC-12 has a higher service ceiling). The one option that we could do in the Aerostar is stay below the ice – the turbocharged engines burn essentially the same about of fuel in cruise at all altitudes – unlike the PT-6. So, as I was reading your excellent writeup, I was thinking that this flight could work out well at 10-12K, in the Aerostar – low enough for little or no ice and just high enough to stay out of the turbulence.

    But considering the PC-12’s turbine engine, 10-12K is probably too low, so my notes were to start out at 16-18k and if we picked up ice, descend as necessary. With virtually no ice below 10K, not much in the way of turbulence, and improving weather as you flew west, the flight in your equipment (or ours) had plenty of outs and was very doable. Glad you had a good ride!

    We did return north that Wednesday in our Aerostar. Generally clear weather most of the way, however there was low level light turbulence up to 12K and high level light-moderate turbulence from 18K to 35k+. Most everyone in the flight levels were trying to find smooth air with the biz jets and airliners that could make it, climbing into the 40s.

    I picked 17K which worked out great for us, nary a bump and just a small 15 knot tailwind with winds at that altitude 270-280 degrees at 95-112knots. With the small tailwind and it being MVFR in KITH, we needed a fuel stop. We did pickup some mixed ice on the descent into KITH – very typical for this time of year.

    • Yes I did. I gave the PIREP of continuous light, occasional moderate ice at 16,000 and then that the ice had stopped at 14,000 after we descended. Later on we reported the bases as we got closer to Cincinnati (which were high).

  • I appreciate that this gives a good insight into the USE of weather products. I see too many articles that, I think, try to show off the knowledge of the author or make us into meteorologists. I will never be a good meteorologist just as most meteorologists won’t fly a single pilot turbine IFR.
    I concur on the issue of comfort. Sometimes I tell the boss that this will NOT be a pleasant flight but it can be done safely. If he and the pax still want to go then it’s on them.

  • First, I would look for the weather ‘Man’ (if there was one on ‘active’ duty) , and pilots at the airport that had flown in the area, to see what they ALL had to say. As a pilot for 50+ years in the Air Force, Mass.ANG, and private sector, talking with people that had/have flying experience(s) in situations like what was going on….. is VERY valuable, essential, and important. Amen, AMEN, and AMEN!

  • John, I don’t really understand why you wrote this article, It appears that all you wanted to do was to compare a multi million dollar aircraft and a typical run of the mill aircraft most of us fly and can afford. If we all had multi million dollar aircraft you wouldn’t be writing this type of article. I find it rather insulting in you doing this, sorry my opinion. It is like Dave Hurshman comparing a RV experimental aircraft with a Cessna 182, what the heck do either one have in common with each other????. Please don’t compare a multi million dollar turbine aircraft with a typical Cessna or Piper or ???? Did I make myself understood???? thanks.

    • Sorry you didn’t like the article, Joe. The point is to help us all try to make the best weather decisions we can—readers consistently tell us that’s one of the most important topics they want to read about.

      The weather does not care what you’re flying (that may be the most important lesson of all). Those screenshots are exactly the same no matter what your airplane. As I mentioned in another comment, I actually think this was an easier flight in a 182 than a Pilatus.

      Same airplane? Of course not. But the decision making process is the same for both, just with different tools and options.

  • This is way above my skill level but for what it’s worth I would have waited until the pressure gradients were farther apart (picture above ‘Satellite and Sigmets); keep a weather eye out after 1612 Z. I would fly over airports in case of icing or other emergencies.

  • John, thanks for your detailed thought process in this go/no-go decision making. It’s very educational and a powerful learning experience or us all. My friend Brian Turrisi on the COPA forum recommended this.

  • Great article, John. As you know we fly the same aircraft type and I would have also been a “go” for that flight. Having an “out” for the icing was a big deal in my thinking. While the PC-12 does burn more fuel at, say, 10,000 FT, not a lot more and it is perfectly happy there. If had been picking up constant moderate ice, I would not hesitate to descend as low as the MEA/MVA and motor on.

  • Sometimes I wonder if maybe we don’t have too much information. To the point that we’re more likely to die from hypertension than an airplane crash. Maybe the autonomous airplane idea is the best. Just let the computer do the analysis and fly the flight while we relax.

    • I appreciate the sentiment, Stephen – someone usually adds a comment on our Go Or No Go articles that, “you forgot the Skew-t/K index/etc. so I can’t make a decision!” I just shake my head. I admit I don’t spend 45 minutes doing weight and balance, either.

      However, it does seem that weather is one area where more information (up to a point) is better. This isn’t an emotional decision about whether to marry a certain person; knowing more about the atmosphere you’re going to fly in generally helps you make better decisions. Yes, we survived 25 years ago without datalink weather and icing forecasts, but the accident record due to weather was significantly worse. Seems like something is helping.

  • Flying a non-turbo Mooney, I would probably have made this flight and just stayed below all the nasty stuff. But that’s if I was alone in the cockpit. If my wife was with me, she would not have been comfortable taking off into those conditions so we would likely have enjoyed some extra time in Pittsburg (if such is possible!).

Leave a Reply

Your email address will not be published. Required fields are marked *