miércoles, 26 de abril de 2017

Decision Time

Some decisions don't allow the luxury of contemplation. Every instrument pilot knows at least one of these decisions in the depths of his or her cloud-flying bones: the missed approach. Making a decision while still descending and a mere 200 feet above the ground (lower for Cat II+) only works because the decision is binary. You see the expected environment and continue or you don't and you climb away.

Pre-loaded decisions are a fantastic safety tool, but we so rarely need them that we end up unprepared to effectively use them. This applies to far more than a missed approach, but let's start there.

Real-world instrument training under the hood leaves pilots woefully unprepared for a real approach with low visibility. This is possibly the best reason to get some real IMC time in training. One-half mile of visibility at 200 AGL on a typical three-degree glidepath means you can see the approach lights peeking through the murk, the threshold, and some puddles on the pavement. Scratch the bit about the pavement if it's night.

To immediately measure visibility the moment you break out, you must know what you expect to see. That's your yardstick. Is this an ALSF-2 lighting system? Just a MALSR? Maybe this is a non-precision approach with an ODALS? (They're out there. We have one just down the road from my home base here in Portland, Maine.)

Each of these systems are a different shape and different length from the threshold. You should have a minimum amount of lights on the far side you expect to see, which might include a certain number of runway lights when more visibility is required. You should know how far those lights extend from the threshold and how far you will be from the beginning of those lights. The point is you must know beforehand how much lighting you expect to see.

You should also know where to look. Crabbing down the localizer in crosswinds, pilots often forget that a ten-degree correction nose-right means those lights will be 10-degrees to the left. Anticipating that removes the moment of confusion when the lights pop-out off center. Or if the lights appear in a different place—or at a weird roll angle—you know something is wrong and a missed approach is the safest action.

The concept becomes more powerful if you expand its use. Take a non-precision approach with a published VDP. The VDP is the last point along the approach where you'll likely be able to land straight-in without channeling your inner anvil. So know where that point is and watch it by distance on your GPS or by time. A breakout before that point is a pre-loaded straight-in. After that point, it's a pre-loaded circle-to-land with a pre-chosen runway using a pre-planned path. Or, if you don't dance circles, it's a missed at the VDP. This is a decision gate: you have only two choices, and passing the gate only one remains.

This tool can be applied even more broadly. You're on a base-leg vector to the localizer with a tailwind. At what point will you query ATC about a turn if one isn't forthcoming? What would you do if the frequency was busy? Use the ident function on your transponder? If you were about to pass through, would you turn inbound or just keep going?

That last one is complicated and has been discussed in IFR Focus #1. But the point is that we can often predict moments where a decision must be made well before we get there. That means we can make an A-B plan, criteria for which option we'll choose, and a point at which we'll decide without hesitation.

There are so many places in regular flying where this happens: approaching weather and needing a deviation, requesting a new altitude before entering icy cloudtops, short final when struggling to stabilize the approach, floating on touchdown ... it just goes on.

The takeaway on all of these is that a pre-loaded decision before you reach that moment of truth reveals actions that might make a snap decision unnecessary, as well as empowering you to make the right call without hesitation if you must.

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