IMG Feature: The Right Seat
by Brian J. Thomas
FAA Certified Flight Instructor


Well, I suppose I should start out with an admission of the somewhat-obvious: The Right Seat will be a quarterly IMG Feature, as opposed to a monthly as originally planned. This is in part due to overall space considerations (just look at all them new games).

Last time (April) while in the right seat we explored the dynamics of flight in relation to airspeed and Bernoulli's Principle and other factors involved in creating Lift. We also looked at critical airspeeds, or "v-speeds," and then applied all of this information to a typical takeoff situation. This month, since presumably we're still floating around in three dimensions somewhere, we'll walk through the sometimes enigmatic process of landing the aircraft. Later in this series we'll come back to discuss some of the finer points of aerodynamics and maximum performance takeoffs and landings.


Glideslope? We don't need no stinking glideslope!
It is often said that the way to assure a good landing is to fly a "stabilized approach." The word "stabilized" here refers to maintaining precise airspeed and attitude control throughout the landing sequence, and basically not letting the aircraft "get away" from you. Larger aircraft, because of their high weight and landing speeds, absolutely require that the pilot establish stable descent rate and airspeed during the entire approach sequence. With larger aircraft, this is somewhat easier, since, once stabilized, the inertia of the airplane will resist changes, whether introduced by the user or by wind gusts.  While not as crucial, perhaps, smaller aircraft still benefit from a stablized approach, if only to reduce pilot workload and make for safer, more accurate, and consistent landings. (According to the NTSB, almost 25% of all general aviation accidents result from under- or over-shooting the runway.)

The key to flying a stabilized approach lies in a thorough understanding of your aircraft's performance characteristics, or "numbers" as they are sometimes called. Typically, before you jump into a new aircraft and roar off into the bright summer sky, you first spend some time with books, especially the POH (Pilot's Operating Handbook), learning the airspeed ranges that are appropriate and safe for that particular aircraft. Then, if you really want to do it right, you go up with someone who knows that aircraft and practice and experiment until you "know the numbers" firsthand. While the aircraft manufacturer provides ranges and target airspeeds, for smaller aircraft, they do not typically provide a true "approach profile," which is why you go up and experiment. 

Approach profiles are developed for all the standard types of approaches, and are used to give the pilot a ballpark idea of what he should be doing, and, when, throughout the approach.   Elements include desired airspeed, configuration (flaps, gear, etc.), and altitude for the different segments of the landing approach. Profiles also identify preferred times and distances for standard configuration changes (gear down, final approach speed, etc.).

The specifics of the approach—the speeds to fly, for instance—will depend on a variety of factors, including aircraft weight, winds, outside temperature, and field elevation.  This will affect when you decide to do certain things during the approach, but overall, only the general structure of the approach profile should be studied and memorized.  We won't worry about most of these for computer flying. But what we do need to worry about is determining how to make the airplane do what we want so we can fly our stabilized approach and hear the sweet kiss of rubber and tarmac.


Boring blue holes — Airwork.
Let's go up and try this out. We'll do some "practice maneuvers," just maneuvering and seeing if we can nail the critical airspeeds.  We'll shoot an actual approach, later.  

The most important thing to remember in the following is to try to get out of the habit of "flying by instruments." What you see out the window is more important, and Flight Simulator's "perspective" animation is good enough to let you fly like a "real" Private Pilot in Visual Flight Rules. Instruments are used to give you a check of what you're doing; the horizon (out-the-window, not the gauge) is the important thing to monitor. This type of flying is the most basic thing any student pilot learns, but an increasing number of "real-life" flight instructors are finding that it's difficult to get their "Flight Simulator"-educated students to kick the "instruments" habit!

Don't believe me?  Well, according to the Federal Aviation Regulations, all you need for VFR flight is an airspeed indicator, an altimeter, and a magnetic compass. Those are THE flight instruments. No artificial horizon, no vertical speed indicator, no gyro compass, no radio navigation equipment.  Lindbergh had more!

What's the pay-off for you?  Well, for a start, your flying will become much more precise.  But enough jabbering: on to the lesson.

Load up Microsoft Flight Simulator (our reference simulator, but you if you have something like Hellcats — improvise and take off in the stock Cessna from Chicago's Meigs Airport. Don't forget to raise your gear (even though this doesn't affect anything in FS4, it does in other simulators, such as Hellcats over the Pacific). Climb to 3,000' indicated altitude (which is really about 2400' above ground level, since Meigs-proper is 592' above mean sea level). Level the aircraft and power back to around 2000 RPM. A key thing to remember in all these "tests" is that the aircraft takes time to stabilize to any new condition, therefore following any changes you need to wait to see the true results. In larger aircraft this is even more true, as their higher inertial factor makes for long response times. If you have trouble stabilizing the altitude, try using the Vertical Speed Indicator (VSI) as your guide instead of the altimeter. The VSI responds more quickly to the "trends" of the aircraft.

Now, notice that in level flight, at 2000 RPM, the Cessna stabilizes at an airspeed of 123 knots. Look out the window. Note the distance of the horizon line above the "nose" of the airplane (or under the cross-hairs, if you have those turned on). If you ever want to maintain level flight at 2000 RPM, from now on, you know that all you have to do is settle the nose at that approximate position and wait for the instruments to stabilize.  This is what it's all about: predictability. Now, throttle back to 1300 RPM while keeping the aircraft level (that is, maintain the altitude), and note your new pitch angle, and maintain it. This configuration should stabilize at 85 knots, straight and level. Once it does, since you're in the safe flap and gear operating ranges, in one fell swoop turn the carb heat on, go to flaps 10 (first notch), and drop the gear. As the airspeed decreases, watch it carefully, and when it hits 80 knots, use the trim (should need trim up) to maintain 80 knots. After a moment, the aircraft should stabilize at a 500 feet per minute (fpm) descent rate. This is an ideal reference descent rate for landings.

According to the FS4 manual (if you really dig, as it's not listed in the aircraft specs in Appendix C), the approach speed for the Skylane is 70 knots. Basically, this is a standard derivation of the aircraft's clean (i.e., flaps and gear up) stall speed (Vso). When not specifically stated in the Pilot's Operating Handbook, the standard rule of thumb is to fly the approach at a speed 1.3 times Vso (see April IMG for an explanation of v-speeds). Since performance information in the FS4 manual states that Vso is 54 knots, the safe approach speed would be 70 knots. In a real aircraft the POH would probably state a safe range for landing speeds of 70 – 80 knots. We'll assume this to be the case. In larger aircraft, a specific speed is calculated for every approach based on conditions such as estimated gross weight and atmospheric conditions. This speed is called Vref, and as it's considered the minimum safe approach speed, a "fudge factor" is often added (e.g., Vref + 20 knots). The range given in a smaller aircraft's POH serves the same purpose, and therefore in real flying many pilots would start the approach at (in this case) 80 knots and go to 70 only during the final approach leg. However since FS4 is so squirrelly in it's "realism" (i.e., barely controllable, let alone stabilized), we'll just stick with 70 knots throughout the approach.

But wait, you say — we're flying at 80 knots now. Right, so drop your flaps to 30 and power back to 1150 RPM. This will give 500 fpm at 70 knots. Piece of cake, right? Well, it takes practice in both simulated and real life. 


On the Numbers
After we're comfortable with these procedures, we can draft up a little approach profile of our own, using a standard left-hand traffic pattern as our guide. Here's what it might look like (in conjunction with number references in red that follow):

  




















Now, using this profile and the numbers above as a guide, reset the simulator, and depart from Meigs again. (1) Full throttle, nose slightly raised, and let the aircraft fly off the ground. Gear up when safe, then maintain runway heading and an 80-knot climb speed (2). At 1300' indicated, turn left for the crosswind leg (3). Not too steep of a bank (FS4 is notoriously easy to overcontrol). After 90 degrees of turn, you should be on a heading of 270 degrees (I often use the compass as I find it's easier than messing with the view keys all the time). After a few seconds, turn left again to enter the downwind leg (4), and continue climbing until you reach standard pattern altitude of 1600', where you'll level off and reduce power to 1300 rpm. This all happens very fast in FS4, and just remember it takes lots of practice. In real life, Students spend hours and hours flying the pattern (a.k.a. touch and go, crash and dash, chirp and burp, down and out, etc.). Okay, so at midfield on your downwind (5) — carb heat on, and gear down and locked. When you're abeam the point of intended landing (6), reduce power further to 1150 rpm, drop flaps 10, and maintain your altitude (1600', right?) until the airspeed reaches 70 knots, then pitch the nose down to maintain 70 (never let it drop below this airspeed).

During the approach, keep an eye on the horizon. Once you reach 70 knots, Keep the nose at the constant angle relative to the horizon. If you do this, your airspeed (and, thus, rate of climb, etc.) will NOT vary, throughout the approach.

Now, take a quick gander back at the runway. Hopefully it's still there :-) When it looks like it's about 45 degrees behind and to your left, start your base leg (7). On base, go to flaps 20, and keep looking at the runway using the view keys to judge your turn to final. It's very easy to overshoot. Sometimes, just to be sure, pilots will start their turn to final just a wee bit early in order to get a better view of the final approach path intercept. It's called cutting the corner, for obvious reasons. When you think the time is right, turn to line yourself up on final, and add more flaps (8). 

Throughout the approach, keep an eye on the far end of the runway, not the approach end.  You want the runway to form a balanced "triangle." If it looks lopsided, you're to the left or right of the runway center-line. In the screenshot above, we're right on course. At this point, even if you decided to maneuver, you wouldn't want to move the nose more than a degree or two, and certainly no more than 10 degrees bank.

If you're too high, flaps 40 will allow for a steeper approach angle while maintaining 70 knots; if you're too low and the runway is rising in your viewscreen, you'll need to add power. If you do, be sure to keep your pitch angle—don't go into an F-16 80-degree climb.

Whatever you do, don't go beneath your target 70 knot approach speed. If you try to "stretch" your glide, which might happen if you raise the nose in response to the airplane sinking too rapidly, you'll just make the situation worse. The correct action at this point, again, is maintaining pitch and increasing engine power for a bit, until you're stabilized again.

Once you get close enough, you should be able to see the Vertical Approach Slope Indicator (VASI) bars next to the runway. These tell you whether you're on an "ideal" 3° glideslope to a predetermined point on the runway. If you're "on glide-path," these will show up as red over white. If you're too low, there will be two red bars. If you're too high, you'll see two whites.  Just remember: "Red over white, you're all right; white over white, high as a kite; red over red, you're dead."  
 
If all goes well, you'll need to start your "flare" or roundout above the runway's approach end at about 50' (650' indicated). This again takes lots of practice to time it right. Too early and you balloon up and find yourself high and slow — not a pretty picture — and you'll need to add either full power and "go around" for another try (fly your pattern again), or add just a bit of power if you have enough runway left and try bringing it down for another try at the flare. If you flare too late, you don't need me to tell you what the result will be. You'll just need a mechanic. And perhaps a medic.

But seriously, it's a good habit to "go around" whenever you're even slightly doubtful about safely continuing the approach. Real pilots don't like to crash airplanes, and real pilots hate crashing simulators just as much—it makes some physically ill. When in doubt, be prudent. 

So now it's time to practice. It's danged frustrating, to be sure, but just think of the reward as being mastery over a small piece of Bill Gate's empire.

Special thanks this month to Robert Dorsett for his copious contributions. If you have ideas for future topics or directions for The Right Seat, please drop me an e-mail at AOL- Baba3; or on the net, n8348220@henson.cc.wwu.edu.