March 2010Features

Easy as ABC

Preparing for an instrument approach

It’s been said that every good landing begins with a good approach. Likewise, every good approach begins with good approach planning. Whether under visual flight rules (VFR) or instrument flight rules (IFR), there is always a list of things a pilot must do to properly prepare themselves for the descent, approach, and eventual landing. And although there are many similarities between VFR and IFR approach planning, an instrument approach always seems to present a few more challenges, making thorough and effective planning even more essential to the instrument pilot.

To help organize the process of completing the various instrument approach planning tasks, let’s group them into four separate phases and label them A, B, B, and C. Bear in mind that while we are discussing instrument approaches in particular, much of this A-B-B-C approach-planning mentality applies beautifully to VFR flights, too. Also notice that the foundation supporting the A-B-B-C approach preparation process contains three recurring key elements:

1. Plan ahead

2. Visualize your plan

3. Double-check everything

To try it out, let’s assume you have already taken all of the appropriate preflight actions necessary to begin your flight and that you are presently en route to your destination on an IFR flight. This is the point where the additional planning needed to actually fly your approach and landing should begin. In fact, the lower the ceiling and visibility at your destination, the earlier you should get started on your ABCs.


Step “A” is short for automatic terminal information service (ATIS) and is just another way of saying, “It’s time to check the weather.” While still a hundred or more miles from your destination, weather information is easily obtained by radio through en route flight advisory service (EFAS), also known as Flight Watch, on 122.0 MHz or from a flight service station (FSS). When within range (usually around 50 miles from your destination) you should be able to receive the destination ATIS, automated weather observing system (AWOS), or automated surface observing system (ASOS), as appropriate. And even if your particular airport is not equipped with any of these services, the instrument approach chart will usually indicate from which nearby airport you should obtain the local weather information and altimeter setting.

Upon receiving the correct altimeter setting, be sure to actually set it into each of your altimeters so that any one of them could be used if needed as an accurate backup instrument. This step may seem obvious, but it’s not unusual to see pilots obtain an altimeter setting and then fail to set it into one, or any, of their altimeters. Remember that using an incorrect altimeter setting invalidates all of the published minimum approach altitudes on the approach chart. In addition to the altimeter setting, knowledge of the ceiling, visibility, winds, active runway, instrument approach in use, and runway conditions goes a long way in helping you to visualize and prepare early for the approach you will be accomplishing.

At busier airports the specific approach in use will be indicated in the ATIS broadcast. But if your destination is a smaller airport, the weather conditions and winds often dictate the approach you eventually will be requesting from air traffic control (ATC). Given a choice, an instrument landing system (ILS) precision approach into the wind is generally preferable. If an ILS is not on the menu, a nonprecision approach into the wind would probably make the next best choice, leaving the nonprecision circle-to-land maneuver your least desirable option. The nonprecison approach and circling approach will require progressively higher weather minimums than the ILS. On your initial contact with approach control or the air route traffic control center (ARTCC) working your airport, be sure to advise them that you have the destination weather or appropriate ATIS information. If you don’t mention this detail, they will have to ask you. So be professional and save them the need to ask the question.

B: Build

Once you have obtained the weather and determined what approach you will be flying, the next phase of the approach planning is to build. By “building” the approach, you are getting physically ready to fly the approach. Begin by first locating and clipping the correct approach chart so it can be easily and quickly retrieved even after you have dropped it on the floor during a night approach—it’s going to happen.

If your aircraft is equipped with an IFR-approved GPS with a current database, load the instrument approach you are planning, selecting your cleared transition routing if applicable. If your destination airport is within a radar service area, upon receiving a heading assignment—your immediate need for the navigational radios is over—allowing you to continue to build your approach by selecting and activating the vectors to final option. Helpful hint: Once you begin receiving radar vectors for the approach, it is a good idea to activate the vectors-to-final function right away so you won’t forget to accomplish this important step.

Also confirm that your GPS unit is in the appropriate navigation mode (GPS or VLOC) as required for the approach. Then, after loading what you believe to be the correct approach into your GPS navigator, double check that each of the approach fixes named in your GPS matches those shown on your approach chart. It’s amazingly easy to load the wrong approach—or improperly load the correct approach—so adding this step to your standard operating procedure (SOP) can and will save you.

Next, tune as necessary the navigation radio that will be displaying your final approach course, carefully adjusting the omni bearing selector (OBS) or horizontal situation indicator (HSI) to the exact published course, and identifying the proper Morse code on the audio. Accurate setting of the final approach course is especially critical during VOR approaches because just a few degrees off the published OBS setting could mean the difference between a successful landing and a missed approach, not to mention the loss of obstruction and terrain clearance.

In presetting your number two navigation radio, consider how it can best be used for your particular approach. For example, if not needed to identify the final approach fix or step-down fixes, consider the missed approach course or holding pattern navigation requirements as other possible options.

Also set and identify your distance measuring equipment (DME) if applicable, confirming the tuned navigational facility is the one required for your approach. If you are equipped with an automatic direction finder (ADF), tune, test, and identify the proper station as needed. And if your approach utilizes marker beacons, be sure to test and set them so that you will see and hear them as you pass overhead. And don’t forget to preset each of the communication frequencies you will be using. Beginning with your number one communication radio, set the control tower or common traffic advisory frequency (CTAF) into the standby side so that a simple flip of the switch later will immediately connect you as needed. Likewise, preset your ground control frequency, if appropriate, into the active side of your number two comm radio for easy access after landing.

B: Brief

By now, you will have loaded, tuned, identified, set, and tested just about every radio in your aircraft, or at least considered its use. Since you are now physically ready for the approach, complete the second B, or brief, in the A-B-B-C list. This is where you will prepare yourself mentally for the approach. Begin with a review of the chart title to be sure, again, that you are using the correct one. Check the minimum safe altitude (MSA) to mentally refresh your terrain awareness for the approach and note the initial and intermediate segment altitudes—along with your approach minimums and required landing visibility. See “Approach Plates Decoded” (November 2009 AOPA Flight Training) for a review of specific approach chart details.

Review the airport diagram for airport elevation, runway length, available lighting, and activation requirements. Airport lighting is critical, particularly at night at the less busy airports where there is often pilot-controlled lighting (PCL). What could be worse than completing a beautifully flown approach to minimums only to be forced to initiate a missed approach because you forgot to activate the lighting at the airport, especially when your fuel is running low? Ouch!

If circling will be required, the airport diagram is also the best tool for visualizing your most effective circle-to-land strategy. Early planning for a circling maneuver is essential to a safe and smooth transition from the instrument approach to a visual landing. Woe is the pilot who attempts a circle-to-land maneuver without giving any thought or planning as to how it will be accomplished prior to breaking out of the clouds. And don’t forget to check the chart carefully for any special notes that may present additional limitations or requirements for your approach.

Just before beginning the instrument approach, make sure you finalize your briefing steps by memorizing what I call the, “How low, how long, and what if?” portion of your briefing. Memorizing these extra-important items will ensure that you will not be looking down at your lap for this critical information during the final approach segment, when 100 percent of your attention should be focused on flying the airplane.

Translated, “how low” means, what is your decision altitude (DA) or minimum descent altitude (MDA)? Also, if appropriate, any step-down fix altitude restriction or visual descent point (VDP) and location should be committed to memory as well.

“How long” means, how will your arrival at the missed approach point (MAP) be determined? For nonprecision approaches this could be a fix depicted on the GPS display, a DME fix, timing to the MAP based on groundspeed, or simply a station passage indication. The key is to determine during this brief phase exactly what your MAP will be based on and then remember it. Of course, precision approaches make this step very easy since the MAP is reached as soon as you arrive at your DA while descending down the glideslope.

That leaves the “what if” question. Very simply, its answer describes the immediate actions required for that particular missed approach. Since all missed approaches require a climb, all you will have to remember is to what altitude you will climb and then determine whether you will be climbing to the left, to the right, or straight ahead. That’s all the detail you really need to memorize for the missed approach. Even if a particular missed approach requires you to track a specific course or fly a specified heading, that information can be reviewed and accomplished once you have initiated a safe climb and turn in the appropriate direction as called for in the initial missed approach instructions. And remember, if you happen to be in the process of circling to land when you initiate your missed approach, always make your initial climbing turn towards the airport to ensure adequate terrain and obstruction clearance.

Now that you have determined all of the required critical information for the approach, begin rolling these numbers over in your head as you near the final approach fix, keeping them going as the approach progresses. As an example, as you intercept the final approach course inbound, your silent chant for the Oshkosh LOC/DME BC RWY 18 approach should sound something like, “Eleven-sixty, zero-point-three DME, left turn to 3,000 feet.”

C: Checklist

Finally, prior to reaching the final approach fix, complete your aircraft’s before-landing checklist, which stands for the “C,” or checklist, of your A-B-B-C approach preparations—including, if appropriate, your activation of the PCL system at the airport.

As with any good checklist, accomplishing these A-B-B-C steps will help minimize the chance of overlooking any important details so that when you hear the words, “Cleared for the approach,” you’ll be fully prepared to accomplish it safely.

Bob Schmelzer is a Chicago-area designated pilot examiner and a United Airlines Boeing 777 captain/line check airman. He has been an active flight instructor since 1972.