Waypoints: Finessing those final seconds

April 1, 2010

February’s column on flying a low approach in South Carolina (“ Waypoints: No Rush”) sparked several requests for more details on dealing

with the risks of flying in weather. Chris Burns, a former airline pilot and occasional contributor to these pages, chastised me for not using the opportunity to discuss personal minimums. A fair comment, but one that can take well more than the 850 words or so allotted for this column. Countless magazine articles, blogs, and books have been written on the subject of personal minimums. The AOPA Air Safety Foundation, the FAA, and many individual instructors have prepared innumerable resources to help pilots assess the risks of individual flights based on numerous factors.

The most common tool is the PAVE checklist. There you assess risks associated with the Pilot, the Aircraft, the enVironment, and External pressures. For Pilots, the pilot is to assess his mental and physical alertness, currency, stress level, and effect of any medications and increase minimums for weather, wind and turbulence, and terrain and runway conditions based on that assessment. Similar adjustments are made for the Aircraft, regarding familiarity with said airplane and its systems and avionics. Unfamiliar airports and terrain would suggest an increase in minimums as well. Finally, External factors, such as a requirement to get home or needs of passengers, should also be assessed.

While the subject of personal minimums is often discussed, tips for those final seconds of a low instrument approach are not. For that, I’d like to offer three things for you to think about before you set sail on your next mission that demands your finest flying skills as you hurtle earthward at some 100 knots and passing within a couple of hundred feet of terra firma while in the soup.

How will you handle the flaps as you pass the final approach fix? Most would agree that the best procedure is to set approach flaps at or just before the FAF to lower the nose and help with the descent; typically, that’s when the gear comes down for those with that option. But when do you go to full flaps? When I fly a low approach I won’t put in full flaps until the landing is assured—or not at all. If the runway is so short that you really need full flaps in order to get stopped, go to another runway. Adding full flaps while still in instrument conditions can destabilize the approach or at least distract you when you ought to be concentrating on maintaining the localizer and glideslope. And then, what if you have to go missed? Some airplanes will barely climb with full flaps. My airplane doesn’t have detents for flap positions. You have to look at the indicator to know when you’ve raised the flaps from full to approach setting—or know the count as you hold the switch. Do you really want to be messing with that passing through 200 feet or so above the ground descending at 600 to 700 feet per minute? At the typical decision height of 200 feet for an ILS you are some 20 seconds or so from impact or touchdown. Don’t make life difficult for yourself.

Next subject for you to think about: Are you really prepared for the missed approach? Sure, you’ve looked at the procedure. You know to climb to a certain altitude and turn a certain direction. But have you thought about what it takes to arrest the sink rate so that your life doesn’t change dramatically in those next 20 seconds? When you can’t see the terrain as you reach decision height, it’s difficult to understand how close you are to the ground. Passing DH without the required runway environment in sight, you must immediately—not leisurely—pitch the airplane up to a climb attitude (that’s usually around 7 to 8 degrees nose up for light airplanes; much higher for a jet) and simultaneously add full power right now (you already set the prop for climb as part of your landing checklist, right?). If you have full flaps in, those must come to the approach (or takeoff) setting. By now you may glimpse the ground, but don’t be tempted to go for the runway. You’ve committed to the missed approach, now stick with the plan. As you go back into instrument conditions, switch back to full scan mode. It’s easy to become disoriented at this point, especially with the added torque and associated P factor. Finally, deal with the landing gear and the rest of the flaps as needed.

Last subject: What do you do once established on the missed approach procedure? You should decide this before you start the approach. Some pilots’ first instinct is to fly another approach to the same runway. Why? If you flew the first approach well but conditions didn’t allow you to land, what makes you think things will change 10 minutes later when you’re back on short final? Low instrument conditions tend to occur in stable air masses, so a sudden improvement is unlikely. If you (or ATC) set up the approach poorly the first time and feel you can fix that mistake the second time around or if the weather is trending upward, it may be worth the try, but in most cases, I vote for diverting to another airport some distance away. Use that time flying to the next airport (pull the power back to save fuel and give yourself time) to get back into “no rush” mode, take a deep breath, and enjoy the learning experience.

Editor in Chief Tom Haines has flown more than 100 models of airplanes in more than 30 years of flying. E-mail the author thomas.haines@aopa.org; follow on Twitter: tomhaines29.