4 min read

Since upgrading to a Cirrus SR22 Turbo a few years ago, you’ve really started using your instrument rating for serious travel. The airplane is well-equipped with a TKS deice system, Garmin glass cockpit, and built-in oxygen. All of those are useful for your typical flights around Montana, Idaho, Utah, and Oregon. Today is no exception, as the mission calls for a two-hour flight from Billings, Montana (BIL), to Boise, Idaho (BOI).

The goal is to get home to Boise after a productive day and a half of meetings in Billings. The route of flight is a familiar one, as you fly it monthly, but as usual the weather is worth considering. You almost always fly IFR, and that’s the plan today, with a route over DLN at somewhere between 14,000 and 20,000 feet. Proposed departure is 1900Z (1pm local). Read the briefing below, then tell us whether you would make the flight or not – and why.


The view on ForeFlight shows a relatively clear map, but you long ago learned that a little rain in the mountains can mean much more than a free airplane wash.


The surface analysis chart shows most of the main weather drivers off to the south and east, with a stationary front hanging out over northern Utah and southern Wyoming:

The prog chart shows scattered rain and storms all across the Northwest tonight and into tomorrow morning:

It does look like that front is slowly sliding off to the east, but not any time soon.


Given the radar image and those prog charts, it looks like today will be a 3-for-1 special, with possible convective activity, in-flight icing, and IFR conditions. A good place to start is the satellite imagery. First up is the infrared picture, which shows a couple different areas of relatively thick clouds.

The visible satellite shows some additional detail – solid clouds around DLN, but clearing up towards Boise.


Next on your list is a look at potential thunderstorm activity. The radar is fairly quiet, but some forecast products suggest things might build this afternoon. For example, there is a convective outlook covering most of Idaho, but no SIGMETs yet.

For a more detailed look, you check out the 21Z TFM Convective Forecast, which shows scattered areas of storms, but off to the south:


The threat of thunderstorms may be slight, but that doesn’t mean it’s smooth sailing. Next you look at the possibility of in-flight icing. With the freezing level around 10,000 feet, that may be in the cards today.

As you might expect, there is an AIRMET for icing between 11,000 and 21,000 feet, although most of your route is unaffected.

Given the terrain across your route of flight, 11,000 is at mountaintop level.

The forecast icing images in ForeFlight are a great tool, so next you look at those, specifically the icing probability at different altitudes. First is 13,000 feet.

Then 15,000 feet, which shows a chance of icing near your departure, but relatively clear skies near Boise.

At 17,000 feet the story is the same to the south, but mostly clear along your route of flight.

Finally it’s time to check PIREPs. A report near your departure airport at 13,000 feet shows negative ice and negative turbulence, an encouraging sign.

Near your destination there is a report of light mixed icing between 14,000 feet and 19,000 feet, although it’s south of your route and in precipitation.

One final PIREP shows light icing at 15,000, but it is further south of your route.

Text weather

Finally, it’s time to review the METARs and TAFs, to see if IFR conditions are in your future. The good news is that Billings is reporting solid VFR conditions, but with the chance of some storms later in the day.

En route, Big Timber is reporting only scattered clouds.

Over Dillon VOR, clouds are solid and a light rain is falling – which matches with the satellite pictures above.

At Boise conditions are excellent and forecast to stay that way except for potential thunderstorms that may pop up around your time of arrival.

Decision time

You’re at the FBO and it’s time to decide what you’re doing. This is no easy VFR flight – there will be some IMC today for sure, and that might bring icing or pop-up thunderstorms. But right now the radar is encouraging, METARs show great VFR conditions, and there aren’t any PIREPs that look too threatening. Are you blasting off or spending the night? Add your comment below.

Air Facts Staff
20 replies
  1. Trek
    Trek says:

    To enhance the realism, these should include factors like: “and it is your daughter’s 7th birthday party. You promised you would be there.”

  2. Mark Fay
    Mark Fay says:

    Anything less than a turboprop and I am not flying the mountains in cloud – for sure not in my 182.

    Mostly for icing reasons.

    Since this plane is FIKI, if I had 200 hours in the plane, I would go constantly looking for an out and staying away from the precip.

    I would immediately reverse for any icing more than slight.

    She’ll have an 8th birthday – be there for it

  3. Kim Hunter
    Kim Hunter says:

    The Cirrus’ equipment capability is far beyond my normal utilization. The scenario is outside my experience.

    That said, there does not seem to be a rock solid out if moderate icing is encountered en route…. I agree with Mark’s assessment.

    P.S. Conditions could be worse than forecast if that Low over Salt Lake develops upper-level support.

  4. Jerry
    Jerry says:

    The hypothetical pilot is moderately experienced in the plane. He knows the route. The FIKI system is installed and presumed full of TKS fluid and fully primed before takeoff. He has oxygen aboard.
    One issue is that NEXRAD coverage over the Rockies isn’t as complete as over flatter states. I assume that he has XM or ADS-B in for weather products aloft. The plane has no active radar, but it likely has a Stormscope.
    Icing forecast is a concern but along the route it appears to be localized geographically and may be associated chiefly with convective activity.
    With no passengers the plane can carry full fuel giving several hours of reserve.
    I’d suggest he go, file for FL180 or FL200 and attempt to remain VMC, deviating as necessary to keep in the clear. ATC will likely grant all requests for route deviation as there’s virtually no other traffic at those altitudes. There are MVFR alternates NW and W of the destination.

  5. Bill Levy
    Bill Levy says:

    I am 71, fly a Mooney 252. Have 1500 hours in the plane. I don’t fly single pilot IFR anymore. I wouldn’t do this. Grandkids birthdays aren’t as important. I am happier to fly IFR on takeoff and approach but not in the mountains. In Colorado the safe place to be is 16,000 feet. The mountains in the 14,000. Winds aloft and barometric pressure on each side of the mountains is important.

  6. Buzz
    Buzz says:

    First, there is no critical mission here. If there’s a doubt about this flight being made safely, it will be delayed.

    Second, FIKI of any duration is a “non-starter” for me, TKS, or not. The limit of 45 minutes on the TKS system is just long enough to make me feel a little overconfident and just short enough to get me into trouble. Thus, if I have to fly the hypothetical route, I’m going to find a nice hotel, do a little more business, get to bed early after a nice dinner and fly out tomorrow.

    Second (addendum) I’m going to do my Weather Risk Assessment Chart to both my primary destination and to my two secondary alternate destinations. Given the equipment that I’m flying, and, if I take a different route, I’m comfortable that it’s within my personal minimums for IFR, Turbulence, Mtn wave/mechanical turbulence, Icing, and Thunderstorms. I won’t though fly the example’s hypothetical route.

    Third, I’d make the trip but take a different route. I’d fly KBIL to KBZN to LKT V113 to KBOI. I’d file for FL200. This will keep me a little north of the weather and the PIREP provides some encouragement as to the possible absence of icing. It also gives me more AGL for more of the flight so that if something goes bad, I’ve got a little extra margin. As well, it appears from the satellite imagery that if I take a more northern course, I’ll get out of mountain obscuration a bit sooner and if the weather is moving to the southeast, that should result in better visibility and a lower probability of icing as I reach KBOI. The weather in KBOI, however, bears close monitoring given the potential of the Low Pressure area south of there.

    Fourth, I’d commit to two “bailout” points and watch the weather because like Kim, I’m concerned about further development of the Low over Salt Lake and the possibility adverse weather conditions south of KBOI push north resulting in degradation at KBOI.

  7. Bryan
    Bryan says:

    I usually don’t post – however I live in Bozeman and have done trips like this many times in unpressurized pistons (mostly DA-42 twins with TKS). In my humble opinion it’s a fool’s errand in an unpressurized Cirrus (or any unpressurized piston) with TKS.

    This is exactly why you need pressurization, a real de-ice system and preferably a turboprop in the mountains to get above stuff like this. This is simply the minimum equipment required if you want to fly for work in the mountains and not get stuck waiting on weather.

    First of all in a piston the correct route is to Bozeman, down the Madison valley, over the Monida pass if required to the Dubois VOR and over the low ground in Idaho to Boise (BIL BZN EKS DBS BOI for those following along on ForeFlight). Going straight from Dillon to Boise is just a dumb idea. That is some of the roughest country in the lower 48, there are no roads and no diverts. If memory serves a few years back a Bonanza went that way going the other direction and they didn’t find the crash site until Spring.

    In addition going straight over the top of 11,000 foot mountains at 14,000 is a recipe for a very uncomfortable ride at best and a dangerous situation at worst, those mountains squeeze moisture out and often have horrendous downdrafts (especially on the backside of the mountains where you have flight planned). Lenticular wave clouds might be academic if you live on the East coast, but here they are common and should be headed as they are a tip off to high winds and mountain wave.

    I fly regularly with oxygen, and I am regularly in the mid teens. This risk can be mitigated with planning and keen attention (always have a pulse oximeter handy to check your blood oxygen!). On a few flights the weather has pushed me up to 18,000 feet and higher. This is something that should be avoided, planning for 20,000 feet unpressurized is simply asking for trouble. I say this as a former F-18 pilot who has operated at 50,000 feet and trained in the pressure chamber at 24,000 feet unpressurized. Trust me you lose useable consciousness very quickly at 20,000 feet – you might have a minute or so (and if you are in your forties and not extremely fit it’s likely that you will lose consciousness just as fast or faster at 20k than we did at 24k feet when we were in our 20’s and very fit).

    Now some people will say TKS is great, and I would agree that it does the job if used correctly. But after running out of TKS in a snow storm that we didn’t expect I would prefer a more robust solution. Simply put flight into known icing in small planes should be avoided. I’ve seen incredible icing over those mountains – so bad the PC12 I was in couldn’t climb – not a situation I would like to repeat in any aircraft, especially a piston.

    I know people will say, I can’t afford a turboprop or a pressurized aircraft. I would counter that there are lots of P210’s and Malibu’s out there that are very affordable. Now just to stir the pot a little more – as a guy whose first civilian aircraft was a Columbia 400 I have to say that a turboprop like a Meridian M500,M600, TBM or even a PC12 are significantly easier to fly than a Columbia or Cirrus! This scenario demonstrates it perfectly – in a turboprop you climb straight up above the weather, you have robust anti ice systems, radar, and can get above more nastiness – you have more options, and that is easier.

    My final point is this, if you have a million dollars to buy an airplane, or $700k or even $300k than you have the money to pay a young flight instructor to fly with you and keep you out of trouble!

    Safe flying!

    • Danny
      Danny says:

      Bryan, in this thought experiment, I would have launched. At first. Then I read your post. You’ve changed my mind. I’m spending the night, and maybe trading my turbocharged Bonanza for a Malibu.

  8. Robert Thomas
    Robert Thomas says:

    Hell No! My take on Cirrus equipment is that it is to get you out of trouble. It is not to go looking for it. Get a pressurized turboprop if this is your mission.

  9. George Catalano
    George Catalano says:

    Well, having the benefit of learning to fly in Colorado, I would label this is a dicey flight. Could end up ‘easy breezy’ or just one of those ‘why am I up here disasters’.

    Forecasting in the mountains is bewitchery at best. Typically incorrect and usually worse than one anticipated. Throw in electrical emergency or mechanical emergency and you are in for a really bad day. I used to trust airplanes – now I just assume everything will go off line or break when it’s the absolute worst possible time.
    Stay home go in the AM !

  10. Sparky
    Sparky says:

    Reading these comments helps me make a difficult decision easier; selling our beautiful, reliable Cessna T-210 of 15 years. I have had 38 years of incident-free but very conservative flying and am lucky to usually have my wife in right the seat who is a CFII. However, as I have aged and looking for a plane to take us on retirement travels we no longer feel comfortable (at all) flying a single piston, as we have done for years, at night, in IFR or over the mountains even in VFR. We have agonized over this decision for years and have analyzed all options. Conversations with our flying friends have gone in all directions of course. “Have to have a twin, don’t get a twin” eye rolling when I mention the cirrus parachute. etc.. We even bought a partnership in a PC-12 which has been nice but I still have that same feeling at night IMC despite the reliable turboprop. And as Bryan said above that has limitations also. The proposed flight to Idaho is not one we would do as planned but we would modify as others had suggested. More importantly however is what would we do it in? The clear choice will be a Cirrus. For two experienced conservative pilots, who don’t see an advantage in a piston twin and can’t afford a pure turbine, having that parachute over mountains, in IMC or at night will be our second engine. The weather scenarios will always be challenging and we will always be conservative on our no-go decision because we can control this. We can’t control when the engine blows.

  11. Low Wings
    Low Wings says:

    Bryan absolutely nailed it! Night IFR/IMC over mountainous terrain such as found in Idaho and Montana in a piston single is a fools errand. If you think otherwise, look up the recent NTSB report about N761YZ.

    Regardless of how many fancy avionics, anti-icing playthings or parachutes installed, there is no avoiding the risk up front, the single point of failure presented by the lonely Continental engine whirring away in front of the pilot. It will continue to peacefully whirr away until it doesn’t, and then the hapless pilot will be called upon to do his best imitation of D B Cooper, and if this unfortunate event should occur over the mountains of central Idaho, he may not be found for days or weeks!

    Yes, it is common knowledge that engines in new modern Cirrus aircraft are reliable and unlikely to suddenly stop producing that comforting whirring sound, but some do, and the pilot will have a few moments of euphoria while descending under the canopy of the chute into some of the most rugged wilderness in North America.

    If our hypothetical pilot really wants to conduct these types of flights in this part of the country, my best advice is to sell the Cirrus and buy a FIKI pressurized twin in which he could quickly climb to and comfortably cruise in the flight levels, on top, above all the ice and clouds, all the way back to the warm, welcoming lights of the Boise area.

  12. CT
    CT says:

    I don’t understand all these people who think it is so much safer to be at FL200 on a mask to avoid the “potential” for light ice in a well equipped plane.

  13. Jorge Lange
    Jorge Lange says:

    “To enhance the realism, these should include factors like: “and it is your daughter’s 7th birthday party. You promised you would be there.” ” If that’s the case, leave a week earlier, spend extra time with the wonderful 7-year old. Lots of weather options in that case. Or, since it was well known ahead of time that the birthday was coming up (no surprise), and one had to be there come hell or high water, go commercial.

  14. Trent
    Trent says:

    While I’m not an experienced pilot (student pilot with 34 hours), after reading the scenario and reading all the comments. I believe with the weather, piston Cirrus and harsh terrain below it should be a no-go unless you reroute and are very familiar with the surrounding area like Bryan said above. If it’s sketchy weather but you go despite odds and you end up crashing on the way then you never made it anyway, why risk it! And like others are saying if it’s very important to get back (like child’s birthday), do what I’ve heard many CFI’s I’ve known do. Buy an airline ticket ahead of time, if for some reason you decide to no-go you can airline it back (if they’re not flying you know it’s bad weather) or if you decide to go in your plane you just roll the airline tickets for later.
    Just my thoughts after asking my CFI on the topic. Again I’m a student pilot with not a lot of experience, just curious to hear what others think

  15. Bob McHale
    Bob McHale says:

    No go. No reason to. Ice? Possible convection? Cumulo-granite? TKS (not FIKI) leaves surfaces on Cirrus uncovered for ice. Been high and not pressurized sucking on a hose…not fun. Eat, drink, sleep, and launch in better weather. Even if birthday, anniversary, wedding/funeral for best friend.

  16. Patrick Langerman
    Patrick Langerman says:

    IN 1978 Red McCulloch and and another pilot with around 5000 hrs between them in a Piper Comanche 250 iced up and landed in a snow covered field gear up, slid to the far end of the field hit a stone wall and died. Flight was from Idaho to Ogden Utah. Icing is no joke. Rent a car if you need to get back to work.!!! Red and his buddy worked for Thiokol doing rocket motor design.

  17. KREDFlyer
    KREDFlyer says:

    Let’s assume the pilot has not made this trip before and has not discussed this route with a local pilot. Let’s assume this pilot hasn’t received mountain flying instruction. Let’s also assume that it’s spring or summer, and the plane is not equipped with a winter survival kit. In spring and summer there is a lot of convective activity in late afternoons in the Rockies, which is mostly avoidable if you fly early in the morning. Even if you didn’t run directly into thunderstorms or icing on this trip you’re likely to encounter convective activity and turbulence. PIREPS below FL25 are sparse in this area, and inadequate to predict what you will encounter. And it may come as a surprise to some people, but the weather radar coverage in this region is actually very low. I would guess more area is in dead zones than is covered, particularly exacerbated over the mountains within about 10k ft AGL. And even outside of the dead zones I’m convinced a calibration problem exists. Numerous times I’ve observed prolonged precipitation that doesn’t show up on radar, and in the same area on a different day precipitation does show up. Let’s make another reasonable assumption that in the rugged terrain of the Absaroka-Beartooth wilderness, popping BRS may not always be survivable, and even if it is, rescue may not be imminent. A ground party could take many days to reach you, and rescue flight ops could be unable to fly in for many days due to weather. In conclusion, I’d spend the evening putting together a better flight plan that doesn’t go over the Absaroka-Beartooth Wilderness, fly at FL20, evaluate preplanned diversions within glide range over mountainous terrain, realize that radar coverage has numerous holes in the region, and leave early in the morning well before thunderstorm activity tends to develop.


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