The engine and slipstream noise is low, the cockpit is dim, the approach is stabilized with the needles centered, and the view out front is dimensionless gray. Your glances at the altimeter are becoming more frequent as the needle approaches the decision altitude. The middle marker tone begins, two-hundred feet, you look up, no runway. Decision time.
Some pilots make the wrong decision when they're presented with these circumstances. The decision, though, is an excruciatingly simple one: execute a missed approach. Instrument pilots know that the regulations call for a mandatory missed approach if the runway environment is not in sight at the published missed approach point. It's clear, simple, easy to understand and easy to apply to real-world situations. Yet we still find wrecked airplanes short of runways after a failed instrument approach procedure.
The Webster Dictionary definition for the word "minimum" is as follows: "the least quantity assignable, admissible, or possible." Let's reflect on the word minimum for a moment. A minimum is a value that is perhaps much lower than the ideal amount for given circumstances. It's not low, it's not really low, it's the absolute least possible amount. It's an extreme. It defines the absolute edge. Now apply this description to instrument approach minimums. Published approach minimums define the absolute lowest possible altitude (literally to the foot) at which an aircraft can be operated safely on a particular approach segment. Minimums aren't recommended altitudes, they exist to define the absolute extreme to which you can descend if you so choose. Many times chart symbology depicts this on the instrument approach chart profile view by showing a solid line below the published minimum altitude but not above it. That means you can fly above the listed altitude but never below it. I almost never descend all the way to the published minimum descent altitude (MDA) on a nonprecision approach. I prefer to level-off seventy-five to one-hundred feet above the MDA to leave myself an added safety margin. Safety is absolutely guaranteed at or above the minimum altitude listed on the chart, and danger is absolutely guaranteed below it. This is true of any approach.
Minimums are a last resort. Think of the MDA on a nonprecision approach or decision altitude (DA) on a precision approach as altitude options for your last ditch effort to find the runway environment -- the absolute minimum altitude to which you are authorized to descend in order to acquire the needed visual references to continue the approach.
Picture yourself on a narrow, uneven, dark and icy mountain road where the posted speed limit is fifty miles per hour (MPH). Notice the words used there: the speed limit. In other words, the maximum allowable speed you are authorized to drive. Visually depicted the minimum and maximum are the extremes, way out on the edges of the graph or chart. The ideal value is usually somewhere in between. Would driving fifty MPH here under these circumstances be conducive to safety? Absolutely not. Perhaps half of the limit would be a better idea. Fifty MPH is not the recommended speed, it simply defines the absolute edge of what is permissible. It's up to the driver to select the most appropriate speed below this value.
Unfortunately, in flying a traffic citation usually is not the only repercussion for violating the published limit. When a pilot descends below a published minimum altitude on an instrument approach he is elevating the risk level of the flight instantly into the red. He's depending only on luck for his survival. Many have died this way.
There is only one way to stay safe when approaching an airport in instrument conditions, and that is to follow the approved instrument approach procedure to the letter. Any deviation from what's charted equals a drastic and immediate increase in risk because margins are already small in the approach environment. The good news is that we're tasked with a simple mission: do exactly what the approach procedure calls for and don't worry about doing (or even thinking about) anything else. Are the required visual cues clearly visible at the missed approach point? If so, land if in a position to maneuver normally to the runway. If not, execute the missed approach procedure. Do this every time and you'll survive every approach.
Minimums are called minimums because they are just that and nothing else. Back to our flight at the beginning, the obvious and only thing to do at this point is begin the missed approach procedure. The increase in engine and slipstream noise means only that you are traveling away from terrain and obstructions, back to safety and an area of increased margins. From there another decision can be made about what to do to keep the flight operating safely.
