Personal IFR minima

One big source of stress around flying is indecision: if all things (people, weather, and equipment) are perfect, it’s an easy choice to fly; if something’s clearly awful (you have the flu, there’s freezing rain, the plane has a major mechanical problem), it’s an easy choice not to fly. If it’s somewhere in the middle, the stress starts — is it really worth letting yourself or other people down because of a forecast for a chance of X or Y that probably won’t happen?

To reduce that stress, I’ve long wanted to put together sets of personal weather minima. Here’s my first draft, for IFR flight in a Piper Cherokee.

Personal day IFR minima

  • Destination forecast meets standard alternate minima for ceiling or visibility, or a nearby larger airport does.
  • Freezing level forecast at least 2,000 feet above MEA.
  • No worse than scattered CB forecast along route.
  • No severe turbulence forecast along route (at my altitudes).
  • Always within 60 minutes of a usable diversion airport.

Personal night IFR minima

  • All day IFR minima.
  • Freezing level forecast at least 4,000 feet above MOCA.
  • No worse than isolated CB, TCU, or ACC forecast along route.
  • Always within 45 minutes of a usable diversion airport.
  • No CB or TCU forecast at destination.

I don’t want the minima to be so lengthy that I ignore them, so strict that I start making exceptions, or so lax that they don’t really help me make the fly/no-fly decision. I’m very interested in feedback from other pilots — please let me know what you think, good or bad.

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About David Megginson

Scholar, tech guy, Canuck, open-source/data/information zealot, urban pedestrian, language geek, tea drinker, pater familias, red tory, amateur musician, private pilot.
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7 Responses to Personal IFR minima

  1. No Fly Zone says:

    I like your list of IRM minima. The only item that I question (or do not understand) is the 60 or 45 minutes (day/night) flying time to a planed diversion airport. They seem a little long for a single engine aircraft. Am I missing something? Nice to see a new post.

  2. Frank Ch. Eigler says:

    I’m usually shy of anything worse than ISOL CB, but then I usually go with radar imagery in mind for the route of choice rather than CB occurrences over a large generic area.

    Considering that I often carry family, I try to avoid uncomfortable turbulence also, so this cuts out spread-out much-taller-than-flightpath cumulus buildups too.

    • Frank Ch. Eigler says:

      I suppose another way of looking at it is that there are separate *safety* minima and *comfort* minima.

      • Yes, agreed on both points. I didn’t specify isolated CB for day IFR because I know I’ve threaded my way through scattered before, and will likely do it again. I want these to be personal minima I’ll actually follow. Part of it for me is the ability to stay visual — embedded is much scarier.

  3. Gerd Wengler says:

    Hello David,

    May I ask how many hours you fly per year on IFR flight plans, I mean cross country? In any case, allow me to be quite direct, these minima are way to conservative for me. BUT, I am not criticizing you for your decisions, they are just fine with you. I have a T182, fly 200 hours per year, almost entirely long cross countries (I have flown to Europe twice). With your minima it just would not work. I fly to airports that report below IFR conditions as long as there is a chance that it’s a fluctuating phenomenon (fog in the morning, reduced visibility because of snow etc.). I have NEVER been forced to go missed because of this. Your second point for night as an example, you can pretty much forget to fly half of the year in the north-east of the continent with that. And again, that’s fine it’s not a criticism. I “don’t care” about CBs at all unless an actual thunderstorm is right over the airport. I can always get around or under with NEXRAD and stromscope, or if it’s a line, I land and wait. Etc. etc. Why for example do you need a usable diversion airport within 45/60 minutes? I see no reason.

    My personal list is “three strikes and you’re out”. If there are three “obstacles” in the way I will not fly IFR. “Obstacles” would be freezing forecast along the way, thunderstorms forecast (TEMP condition), severe turbulence, night, something not 100% OK with the airplane, low IFR conditions. It served me well. I have almost 4,000 hours, most on IFR flight plans. I think three times (!) I had to divert to a different airport. I had perhaps 5 or 6 missed approaches but mostly I made it in the second time around.

    Good for you to be so conservative!

    Regards,
    Gerd

    • Gerd: thanks for the comment.

      A turbocharged 182 is a much-more capable plane than a PA28-161, in speed, range, altitude, and endurance – I suspect my personal minima would different with that equipment, and that they would also be different if I were flying for a living (I can’t imagine a typical freight dog would get away with staying on the ground when the destination was above minima but below alternate minima).

      I’ve never gone missed either, but I’ve landed a few (legal) low approaches that were far less than pleasant after 4+ hours of flying, and have occasionally diverted locally to a bigger airport. I’ve never flown more than 135 hours in a year, either, so experience and recency play a role.

      But still, the point of my posting wasn’t for other people to adapt my minima; it was to encourage them to write down their own, whatever they may be, to have a fixed reference during to stress and pressure of last-minute go/no-go decision making. It sounds like you already have a good idea of what yours are.

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