Briefing The Slam-Dunk Approach

The reason doesnt matter, but youre way behind the airplane at the final approach fix. Which corners can you cut to safely find the runway?


Where you are, droning along in IMC, when suddenly youre almost on top of the final approach fix and havent planned for the procedure, much less set up the cockpit. How are you going to get safely from the FAF to the runway?

It doesnt really matter why you find yourself here. Maybe you spent too much time at altitude without oxygen and it suddenly dawned on you where you are and what you need to do. Maybe the right engine just committed harikari and is dangling from the wing. Maybe a passenger needs urgent medical assistance. It doesnt

Cessna Aircraft


matter. The problem is youre about to shoot an approach for which you havent briefed yourself or configured the airplane. What are you going to do?

No Recriminations

Almost 20 years later, I can still hear my double-I slyly, gently, calmly reminding me to set up for the approach: “Now, while youre flying straight and level, is a good time to set up for the approach.” He was right then, and hed be right now. Thankfully and whether he knows it or not, hes pretty much always ridden shotgun with me ever since.

There have been times when-about the time ATC cleared me for an approach-I mentally kicked myself for being behind the airplane. Fortunately, those occasions have been few and far between and-like this articles premise-usually involve some major distraction or other problem.

Encountering adverse weather is the most common reason for needing to shoot an approach now. Of course, unforecast or rapidly deteriorating weather just compounds the problem of executing a procedure for which youre not prepared. Maybe the best plan would be to reverse course and backtrack a bit, to better weather? Maybe you should go somewhere and hold for a while, awaiting improvement? (See Frank Bowlins article on page 8 for reasons this could be a good option.) Your fuel state, among other issues, may not make this idea a viable one, of course.

Regardless, being in the air and needing to be on the ground in a hurry is a really poor time to engage in self-flagellation over the reasons why. The task at hand is to get you, your passengers and your aircraft on the ground and in one piece. The time for recriminations will come soon enough. For now, buckle down and concentrate on flying the airplane, and executing the best approach of your career.

How Low Can You Go?

The first bit of information I want when setting up for any approach is the altitude to which I need to descend. In my mind, this is the minimum descent altitude (MDA) for a non-precision approach, or decision altitude (DA) for an ILS or a GPS/VNAV procedure. Along the way, there may be a step-down fix or two, which Ill get to in a moment, but for now, I want to know the MDA/DA. Why?

The main reason is I want to get that value firmly fixed in my mind. When the chips are down, like they are for this approach, a lot is riding on hustling down to the lowest altitude I can reach safely. (If the chips are really down-the planes on fire, or Im running on fumes-the lowest altitude I can reach safely just became the touchdown zone elevation, and Ill plan to fly right down the final approach courses centerline until the wheels touch. But thats another topic for another article.)

Back in the day, Id dial the MDA/DA into the unused ADF. That way, Id have a ready reference if and when, in the heat of the moment, I momentarily forgot the number I needed. Presuming, of course, I didnt need the ADF for the approach. (If I did, and it was my primary navaid for this slam-dunk procedure, I had a whole different set of more serious problems.) Today, my ADF has long since gone to that great used avionics stack in the sky, so I need an alternate method of keeping track of the procedures various numbers. See the sidebar on page 6 for some thoughts.

Stepdown fixes, if any, are a complication. In an bona fide emergency, Id be sorely tempted to ignore them, concentrating instead on a steady descent rate and hewing as closely as humanly possible to the final approach courses centerline. Failing that, I now have two numbers to remember. Ultimately, though, I probably need to write down this stuff.

Using a highlighter on the approach plate itself can help, but bending down or turning our head to find the plate during the approach is distracting us away from Job One: flying the airplane. Either way, thats too much monkey-motion for us, and helps set up an episode of vertigo, right when we need it least.

Once the approachs minimum altitude is “memorized,” its time to figure out what kind of descent rate well need. If youre lucky, youre shooting an ILS or a VNAV approach and dont need to worry too much about it; just follow the glideslope needle. But if the approach doesnt offer vertical guidance, you need to “guestimate” the descent rate youll need on final by comparing the published altitude at the FAF with the MDA, along with the distance between the FAF and the runway. All that is right there on the plate. What? You dont have time to look at the plate? Then compare your current altitude to the MDA and do the mental gymnastics required. You probably want to hustle down there, since-for whatever reason-youre in a hurry.

Flying The Final

These days, we usually have very accurate course guidance down to the runway. It wasnt always that way (see “Non-Directional Beacon”). So figuring out the course to fly down the final approach really should be a no-brainer. Except, that is, when the weather is really down the tubes and the wind is howling. In such an event, you definitely need to figure out a good heading to fly. And if the reason you want to be on the ground now involves imminent electrical system failure, taking with it the avionics youre using for this approach, you probably need no further encouragement from me.

Hopefully, youre being vectored to the final approach course. If not, by the time you finish the course reversal you should have a good handle not only on the winds at your altitude but the correction angle necessary to hold the final approach course. If youre being vectored, and things are happening too fast, start with a five-degree cut into the wind. Unless youre really living right, this wont be close to accurate, but it will help prevent a full-scale deflection off the needed course while you get your act together, drop the gear, set power and prep the cabin/passengers as you cross the FAF.

When the final approach fix fades behind you and your descent is stabilized is a good time to get a howgozit on your heading. Chances are, theres some drift, and you need to make a correction. Take another five-degree cut in the appropriate direction. If the first correction was in the wrong direction and the needle youre following looks like a windshield wiper, take a stronger cut.

Just like flying a “normal” approach, your objective here is to find that sweet spot but, because you got a late start, it might remain elusive all the way to the runway. Whatever you do, dont take more than a 10-degree cut at a time trying to maintain the final, and dont get frustrated.

As you descend on the final, of course, the wind likely will shift direction or velocity. What started as a gentle cross from the left could easily stiffen and shear to the right; a headwind can shift to a tailwind. How will you know the wind has changed? The same as when flying under the hood with your favorite double-I on a sunny day: There will be a bump. Any time theres an abrupt change in the winds velocity, theres going to be a change in the way the airplane behaves. One clear sign is turbulence as you transition from one wind vector to another. A second is the change in groundspeed. A third? You guessed it: the need to fly a different heading for the wind-a larger cut, a smaller one, or one in the opposite direction.

You can guess at the heading youll need to fly down the final, but the bottom line is to fly whatever it takes to keep the needles from breaking out the sides of the instrument. It doesnt have to be pretty-remember, this is a slam-dunk. Your objective is get to a point at which you can see the runway and land on it.

Straight? Or Circle?

Before you leave the FAF, you should know whether to expect to land straight-in from your approach or whether circling will be necessary. The answer will depend on the wind, the runway configuration, the airplanes capability, traffic and ATCs needs. If this is a bona fide emergency-instead of you just waking up to reality-youre justified in using your emergency authority at either a towered or non-towered field to fly a straight-in approach, even if a) its against the flow or, b) requires landing downwind. If not, you should plan to go with the flow and circle if thats whats expected.

But, which way? Ideally, youll have figured out from the approach or landing clearance which way to turn on breaking out; sometimes, though, its not obvious. A quick glance at the approach plate for notes involving the circle before leaving the FAF would be nice; stealing a glance while falling down the final may be necessary. Either way, youll need to know the answer before reaching the MDA.

All Together Now

Again: It doesnt matter how you got into this slam-dunk situation. Youre here. What matters is keeping the dirty side down long enough for the wheels to come to a stop, preferably on a runway.

There are a lot of little nuances and niceties you learn when practicing and flying approaches with the luxury of planning, but todays not that day. Instead, youll have to improvise and, hopefully, do it in such a manner you neither break any FARs or any airplane parts.

In my book, though, once you know the minimum altitude to which you can descend, squint your eyes enough to find the right heading to fly while descending on the final approach course, and know beforehand whether youll be circling or not; youve got the basic information needed to fly just about any approach in a hurry.

We dont advocate cutting corners, especially in for-real IMC. But when the weather has caved, the fuel gauges are bouncing on “E” and your neighbors kid is power-vomiting on your new Garmin, you need to eliminate the fluff and get down to business. Now you know how.


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