IFR Alternates and Minimums Made Easy

Flight under instrument flight rules (IFR) is largely procedural. There’s little room or tolerance for zany spontaneity; if you love surprises, look elsewhere. But although we fly by the book, when the plot thickens, we do in fact have options (although they’re more like regulatory provisions) for choosing a different ending. Usually, the thickening agent affecting our best-laid plans is weather related.


Most pilots with instrument ratings would probably agree that when it comes to an uneventful passage through haze, gloom, or dark of night and back to Mother Earth, an ILS is a much better deal than a VOR approach. Given a choice between the somewhat more relaxed progression of a non-precision descent profile and the relatively more rapid cross-checking required to remain within the allotted confines of a precision approach path, when the chips (and the ceilings) are down, the precision approach is definitely the better of the two. Until there are many more GPS WAAS approaches besides the few now coming online, for a while yet at least, the odds are that if you have to get down through a layer of low clouds, the bases of which might be as low as 200 feet, you’ll be flying an ILS. (Of course, the PAR or precision approach radar that I wrote about last year also qualifies as a precision approach, but I’ll concentrate on the ILS here.) So what is it that makes an ILS so special?

Non-Precision Approaches

I don't know about you, but you might say that I have an approach/avoidance conflict with some non-precision approaches, in particular with VOR approaches. On the one hand, I like them because they cut me some slack if I'm feeling mellow, the weather isn't too crummy, and the ceilings are still comfortably in the neighborhood of the transition point from three to four digits. Then again, particularly with the VOR approaches for which the navigation facility isn't on the field, the errors can really accumulate if your navigation equipment isn't as precise as it once was, and you don't fly them accurately. When the chips are down (along with the ceilings and visibility), that might just leave you wondering-particularly when you emerge from the clouds and the runway (or even the airport environment) is nowhere in sight.

Trivia Teaser – The Lure of the Straight And Narrow

Question: You experience an engine failure at a fairly charitable altitude (say 4500 feet) during a cross-country flight. There aren't any airports within gliding range, but you immediately see a perfectly straight clearing in the heavily wooded area over which you are flying (which fortunately, appears to be relatively flat) You notice that it continues off into the middle distance, at which point it abruptly changes direction by about 25 degrees and continues again in another long, straight line. Why might you not want to even think about landing there?

Rosetta Stone

If you’re instrument rated and current, you almost certainly own at least a modest complement of IFR charts and approach plates. But the odds are that you still make a number of flights under visual flight rules, and if you’re like me, you probably always have a couple of current local sectionals in your flight bag. And then there’s the other half of us who only fly in visual conditions, and who don’t ever so much as look at an IFR chart or approach plate (or quite truthfully for new pilots, those who haven’t yet seen one). If you’re in that latter half, you might be missing out on a few things.

Trivia Teaser: Sticking Points

Question: True or false: The viscosity (or 'stickiness') of a gas actually increases with increasing temperature (unlike a liquid). So even though it becomes less dense when warmed, and its molecules move further apart and more quickly, a gas becomes, in a way, thicker at the same time that it gets thinner.

More Lies My AWOS Told Me

A funny thing happened this morning on the way to the traffic pattern. Actually that’s an untruth; it wasn’t very amusing. In a few years I might look lightheartedly back upon this, because the fact of the matter is, I had to consciously stop hyperventilating.