Editor's Note: This article is the third installment in a five-part series by Master CFI/CFII/MEI Gary Reeves, which discusses the most common mistakes he sees good IFR pilots and CFIIs keep making (and how you can avoid them).
The one-two-three rule is a classic example of an out-of-date regulation from the FAA still being taught today. The rule, which every flight instructor is required to teach, establishes that pilots need to pick an alternate airport if their destination airport is less than VFR and be able to fly to their alternate after going missed and land within 45 minutes of fuel reserve.
While that made sense 20 years ago (before we had datalink weather in the cockpit), it doesn’t make sense now. When I learned IFR, we didn’t have XM or FIS-B weather. We relied on TAFs and FAs (area forecasts), which were large, generalized forecasts covering several states that were issued every eight hours.
It made sense to pick an alternate after your destination because you didn’t have a lot of up-to-date information in the air, especially at small non-towered airports. Today, with much-improved forecasting tools and the availability of datalink weather in the cockpit, telling me to fly into known bad weather and then go to an airport with better weather is just silly (if not dangerous).
Let’s take a look at an example flight plan from KMSL to KCXU.
Why would you ever fly into convective activity, go to KCXU, and then to KMAI if you go missed? It makes a lot more sense to stop halfway at KBHM before you get into bad weather!
I always recommend that all pilots and instrument instructors add a weather alternate to every flight plan, even if it is not legally required. My preference is a Class C airport or the largest Class D airport about halfway to the destination. In case you want to stop, having a variety of different runways, approaches, hotels, and rental cars available will give you good options.
If you are going for an IFR checkride soon, explain to your DPE that you think stopping before you get into bad weather is safer than going missed in bad weather, which is why you would choose that option even though it may not meet the 45-minute fuel reserve rule. By showing the examiner that you are making good aeronautical decisions and not blindly rote-memorizing rules, you will impress them. I promise.