On Instruments: How low can you go?

I’ll bet that many of us have shot dozens of Category I (Cat I for short) ILS approaches in actual instrument conditions, right down to the Cat I decision height/decision altitude and visibility minimums of 200 feet and one-half mile (or 2,400-foot runway visual range, or RVR) visibility conditions. And all of us would agree that breaking out of the overcast and seeing the approach light array and the runway ahead is an experience that can’t be beat.

There’s a lot of focus on ILS approaches in IFR flying because of their lateral accuracy, precise vertical guidance (each dot’s worth of deflection from the glide-slope’s central “bull’s eye” is worth about 50 feet at the final approach fix, and just 6 feet at the missed approach point), and widespread availability. Yes, some RNAV GPS approaches—the ones with localizer performance with vertical guidance (LPV)—also provide good vertical guidance, and these are becoming more widespread. But the ILS remains the gold standard for a lot of us.

But what if the weather is truly awful, meaning below Cat I minimums and deep into low IFR territory?But what if the weather is truly awful, meaning below Cat I minimums and deep into low IFR territory? Low IFR is defined as anything below 500-foot ceilings and one-mile visibility, so for argument’s sake let’s say the weather at your destination features a 100-foot ceiling and a quarter-mile (or a 1,600-foot RVR) visibility. Those are Category II minimums. As a pilot flying a nonrevenue flight under FAR Part 91, this means that unless you and your aircraft have earned authorizations to fly Category II, you can’t even begin such an approach, let alone finish it to a landing. Legally, that is.

Wait, what? Does that mean you can earn an authorization to fly Cat II approaches in your single- or multiengine piston airplane? The short answer is yes. But it’s a daunting task. The regulations for flying Cat II approaches—and their more trying bigger brothers, Category III approaches—are designed to apply to charter, fractional, and airline operators. That means facing much higher safety standards, and a whole lot of hoops to jump through. FAR Parts 135, 91(k), and 121 have training and safety systems in place to deal with authorizations and other regulatory compliance. A lone individual will be swamped.

Here’s why. You start by sending the FAA a letter of intent, stating the Cat II-equipped airports you intend to use, and how the operator (you) plans on complying with pilot training standards. The airports must have certain capabilities as part of their own Cat II authorization standards, such as a tower, an ALSF-2 (approach lighting system with flashers), and touchdown zone and centerline lighting. There must be weather reporting capability, as well as transmissometers for measuring RVRs. Ideally, the transmissometers would be placed at three intervals along each runway served by a Cat II approach: at the touchdown zone, at the runway midpoint, and at the post-landing rollout zone. There must be a standby power system, capable of kicking in and restoring power within one second of a power outage.

Typical approach minimums

If the airport must be certified, then so must the airplane you intend to fly. There will be an audit not just of its certification compliance, but to make sure it meets lightning-strike and high-intensity radiated fields (HIRF) protection standards. A dual-ILS receiver setup will be required—unless your airplane is equipped with a head-up display and/or has autoland capability. (Autoland automatically flies an airplane to touchdown and rollout.) Ditto an inner marker beacon light that illuminates and gives a six-dot-per-second aural alert when passing overhead. (Inner marker beacons are located along the final approach course, right before the runway threshold, at the distance an airplane would be at 100 feet agl—in other words, decision height for a typical Cat II approach.)

As pilot, you need to have an instrument rating, of course, as well as be instrument current and current in type. In this case, “instrument current” means flying at least six approaches every six months—all of them to Cat II decision heights. There will be an oral as well as a practical exam of your flying skills, and your checkride will feature two approaches to Cat II decision heights—one to a landing, and the other ending in a missed approach procedure. One of those approaches can be flown on autopilot, but the next approach must be hand-flown to a flight director’s commands. Oh, and if your airplane has two engines, you’ll be required to do a missed approach with the critical engine set at zero thrust. All the while, the examiner is free to toss out oral exam questions at any time during the practical test.

The approaches and missed approaches can be flown in an approved flight simulator or your airplane, in either actual or simulated Cat II conditions. Last but not least, if you let your currency lapse, you’ll have to have an instrument competency check that will feature—surprise, surprise—more Cat II approaches.

See why so many pilots flying under Part 91 don’t pursue Cat II authorization? Sure, some have earned it, and good for them. They’ve conquered quite a bucket list item.

Maybe the next item on their bucket list will be Cat III authorization. Practically speaking, you’d need to be an airline pilot flying some pretty heavy iron with sophisticated hardware to qualify.

It depends on the airline’s procedures and policies, but some of the same sorts of tasks flown for Cat II approval will be essentially duplicated when testing for Cat III. It depends on the airline’s procedures and policies, but an informal poll of pilots flying for one major airline revealed that using autoland is a standard practice for all Cat II and III approaches, and optional during Cat I approaches. Dual ILS receivers, dual autopilots, autothrottles, radar altimeters, and sometimes HUDs also are aboard, depending on the airline, the airplane, and the approach.

Cat IIIc approaches are the spookiest because the weather is so bad you can’t see a thing, even while touching down. It’s an exercise in discipline, trust, strict adherence to procedure, and faith. The captain flies, the first officer runs the checklists and makes the callouts.

A trip down final on a Cat IIIc approach—meaning no decision height and no RVR limits—would go something like this:

• Monitor weather conditions for touchdown, midpoint, and rollout RVRs.
• Upon receiving the approach clearance, arm autopilot approach mode, and arm the second autopilot.
• Remind ATC that this is an autoland approach, to help ensure that runway critical hold-short lines are observed—so no airplanes or other equipment block the ILS signal.
• At 1,500 feet, the autoland system self-checks, then auto-flare arms, lighting up an annunciator.
• At 350 feet, roll in nose-up trim.
• First officer makes altitude callouts as touchdown nears.
• In case of a missed approach, be prepared for the main gear to touch down as power is applied; the airplane can sink up to 50 feet during the transition to a climb.
• After touchdown, autothrottles kick off in two seconds.
• Apply reverse thrust; autoland will track the runway centerline.
• Brake to a stop.
• Resume breathing.

I’ve seen some debate over whether autoland will automatically track the airplane off the runway and taxi to the gate. So far, the consensus is that no, it’s up to you to taxi off the runway and to the gate. Following the low-visibility taxi lights may help some, but it still must be disorienting. Maybe your salvation arrives with a Follow Me tug, or by using an iPad with georeferencing of the airplane’s position—an urban myth, I was told. Whatever the case, it’s all the more reason to stick with Category I approaches.

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