clumpinglitter (![[info]](http://l-stat.livejournal.com/img/userinfo.gif){kind=small} clumpinglitter) wrote,@ 2006-08-08 19:11:00 |
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I'm bliiiiiiind!
Every student pilot has to have a minimum of three hours of hood training. The purpose of this training is to help you save your own life if you accidentally fly into a cloud. Or, maybe you'll be flying at night and lose reference to the ground. It's hard to fly even straight and level when you can't see outside. You have to use your instruments, obviously, but you also have to be orderly about it. No single instrument can give you enough information to fly and navigate, and on top of that, instruments can fail, so you have to use them all. There are three basic tasks when flying by instruments: crosscheck, interpretation, and aircraft control.
The crosscheck is done with the all-important instrument scan. Use a methodical and continuous pattern of looking at each instrument in turn, never staring or skipping. A good scan will help you avoid fixating, which is staring at a single instrument. It can happen when you're making a correction -- for example, if you notice you're off altitude, staring at the altimeter will almost always cause a drift away from the heading. When you notice the heading deviation, staring at the DG will almost always cause a deviation in altitude. You'll go back and forth and accumulate errors unless you learn to keep your scan going. You should look at each instrument for a second or two, but no longer. And spending any less than a second will probably be too fast for you to effectively take in what the instrument is displaying.
Another common error that's easily avoided by a good scan is instrument omission. Instruments go better together than when separate, like gin and tonic. Disregarding what an instrument is trying to tell you can cause you to make errors. For example, don't omit your compass -- you may not realize how much your DG has precessed. And, a failed instrument will come to your attention much earlier if you're crosschecking it with other instruments. Errors of emphasis also go along with this. Your AI is handy because it's the only instrument that directly shows the airplane's attitude, but its indications aren't precise enough to detect a tiny error in bank. You can be ten degrees off your heading before you know it if you use the AI and skip the DG.
There are a couple of strategies you can use for instrument interpretation. One is the "primary and supporting" method, where we divide the instruments into pitch, bank, and power categories. Pitch instruments are the AI, altimeter, ASI, and VSI. Bank instruments are the AI, DG, compass, and TC. The engine instruments and ASI are for power. And each instrument changes role from primary and supporting based the situation. For example, when flying straight and level, the DG is primary for bank, and the altimeter is primary for pitch. The AI, compass, and TC are supporting for bank, and the ASI, VSI and AI are supporting for pitch. If you want to establish a climb, the AI becomes primary. Once the climb is established, the AI goes back to supporting, and the ASI becomes primary. It sounds complicated, but it all makes sense and becomes natural after you learn how each instrument works. But it's still not as easy as being able to just look out the window.
I prefer primary/supporting, but the "control and performance" method is probably easier for the purposes of a VFR pilot. With this method, the instruments are divided into navigation, control, and performance categories. Control instruments are the AI and engine instruments. Performance instruments are the the altimeter, ASI, VSI, DG, and TC. You use the control instruments to establish an attitude and power setting, and you then use the performance instruments to keep an eye on how the airplane is doing. Then, use the navigation instruments to avoid getting lost.
The last element of flying instruments, control, happens only after you've interpreted the instruments and determined your flight situation. You'll learn how to set the power, pitch and bank instruments for proper control over the airplane even when you can't see outside.
Let's step through how to do a constant-airspeed climb using the control and performance method. The airplane starts out in stable straight and level flight, say at 100 kts. Our little trainer can't do 100 kts in the climb, but it can do 80. So, we'll use 80 kts as the target climb airspeed. Attitude changes are done by 1. Pitch, 2. Power, and 3. Trim. So, the first step is to establish the climb. Using the AI, pitch the miniature airplane up one bar high. Then, add full power. Then, trim. Your target airspeed is 80, so you'll probably have to make some pitch and trim adjustments as the airplane gets itself stabilized in the climb. Ignore the leans. At some point, you'll want to level off. Take 10% of your climb rate and lead the level off by that many feet. You're probably climbing at something like 500 feet per minute on the VSI, so start levelling off about 50 feet below your target altitude. Inertia will carry the airplane up through the remaining 50 feet (you may actually need to use less than 10% if your airplane is a real dog). Anyway, the procedure for this pitch change is just as the one we used to get into the climb: pitch, power, trim. So, first use the AI to level the miniature airplane. If your airplane is a real pig, you may want to just let it accumulate airspeed at full power back up to almost 100 kts before you bring the power back to the cruise setting. But when that's done, trim off the control pressures. During the climb, use the DG, TC, and compass for information on how you're doing with holding heading. Fun!
Turns to headings are a little different than when visual. We always use a standard rate turn when under the hood. At normal cruise airspeed, this will usually end up being about 12 degrees of bank angle. Use the AI to establish the turn, then use the TC to monitor how well you're maintaining standard rate. Keep the tick marks on the TC lined up as well as you can -- this may mean adjusting your bank angle. As with a visual turn, lead your rollout by 50 percent of the bank angle. A standard-rate turn will seem slow. If your masochistic, you can do a standard rate turn with just the magnetic compass. Just turn at a rate of 3 degrees per second, and lead or lag your rollout as necessary (remember UNOS).
If you get distracted while flying on instruments, you can get yourself into an unusual attitude. This can be a nose-high attitude or more commonly, a nose-low banking attitude, but either way, you didn't intend to do it, and unless stopped, you can get into lots of trouble. If you look up from your chart and the instruments are all a jumble, just look at the ASI. If it's reading low, then your nose is pointed up. Use the AI to push the nose down to level, and simultaneously add full power -- you could be periously close to a stall. Use the TC to level the wings.
If the ASI said your airspeed was high and increasing, then pull your power back to idle and use the TC to level the wings. These actions will help to reduce any danger of bad load factors. The airplane is now diving straight ahead, so use the AI to smoothly pull the nose back up to a level attitude. Remember that the AI and DG may have tumbled in an unusual attitude, so keep your scan going. Because the altimeter and ASI are going to give you really valuable information about your pitch attitude.
After you can do straight and level flight, turns, climbs, and descents without much thought, you can start tracking VORs and NDBs.
When flying instruments, your workload is a lot higher than it is when you're visual. So don't tolerate much deviation in heading or altitude. If you do, errors will accumulate, and it will make it much harder to navigate, talk to ATC, play soduku, and chat with your passenger. Practice small corrections. Proper trim is essential.
All of this is moot without a thorough knowledge of how the instruments work. So prior to instrument flight, make sure you have a good no-shit understanding of what powers each instrument, how they get their information, and what sorts of errors are inherent in each instrument. Instrument flying is the most fun there is, for real.
Every student pilot has to have a minimum of three hours of hood training. The purpose of this training is to help you save your own life if you accidentally fly into a cloud. Or, maybe you'll be flying at night and lose reference to the ground. It's hard to fly even straight and level when you can't see outside. You have to use your instruments, obviously, but you also have to be orderly about it. No single instrument can give you enough information to fly and navigate, and on top of that, instruments can fail, so you have to use them all. There are three basic tasks when flying by instruments: crosscheck, interpretation, and aircraft control.
The crosscheck is done with the all-important instrument scan. Use a methodical and continuous pattern of looking at each instrument in turn, never staring or skipping. A good scan will help you avoid fixating, which is staring at a single instrument. It can happen when you're making a correction -- for example, if you notice you're off altitude, staring at the altimeter will almost always cause a drift away from the heading. When you notice the heading deviation, staring at the DG will almost always cause a deviation in altitude. You'll go back and forth and accumulate errors unless you learn to keep your scan going. You should look at each instrument for a second or two, but no longer. And spending any less than a second will probably be too fast for you to effectively take in what the instrument is displaying.
Another common error that's easily avoided by a good scan is instrument omission. Instruments go better together than when separate, like gin and tonic. Disregarding what an instrument is trying to tell you can cause you to make errors. For example, don't omit your compass -- you may not realize how much your DG has precessed. And, a failed instrument will come to your attention much earlier if you're crosschecking it with other instruments. Errors of emphasis also go along with this. Your AI is handy because it's the only instrument that directly shows the airplane's attitude, but its indications aren't precise enough to detect a tiny error in bank. You can be ten degrees off your heading before you know it if you use the AI and skip the DG.
There are a couple of strategies you can use for instrument interpretation. One is the "primary and supporting" method, where we divide the instruments into pitch, bank, and power categories. Pitch instruments are the AI, altimeter, ASI, and VSI. Bank instruments are the AI, DG, compass, and TC. The engine instruments and ASI are for power. And each instrument changes role from primary and supporting based the situation. For example, when flying straight and level, the DG is primary for bank, and the altimeter is primary for pitch. The AI, compass, and TC are supporting for bank, and the ASI, VSI and AI are supporting for pitch. If you want to establish a climb, the AI becomes primary. Once the climb is established, the AI goes back to supporting, and the ASI becomes primary. It sounds complicated, but it all makes sense and becomes natural after you learn how each instrument works. But it's still not as easy as being able to just look out the window.
I prefer primary/supporting, but the "control and performance" method is probably easier for the purposes of a VFR pilot. With this method, the instruments are divided into navigation, control, and performance categories. Control instruments are the AI and engine instruments. Performance instruments are the the altimeter, ASI, VSI, DG, and TC. You use the control instruments to establish an attitude and power setting, and you then use the performance instruments to keep an eye on how the airplane is doing. Then, use the navigation instruments to avoid getting lost.
The last element of flying instruments, control, happens only after you've interpreted the instruments and determined your flight situation. You'll learn how to set the power, pitch and bank instruments for proper control over the airplane even when you can't see outside.
Let's step through how to do a constant-airspeed climb using the control and performance method. The airplane starts out in stable straight and level flight, say at 100 kts. Our little trainer can't do 100 kts in the climb, but it can do 80. So, we'll use 80 kts as the target climb airspeed. Attitude changes are done by 1. Pitch, 2. Power, and 3. Trim. So, the first step is to establish the climb. Using the AI, pitch the miniature airplane up one bar high. Then, add full power. Then, trim. Your target airspeed is 80, so you'll probably have to make some pitch and trim adjustments as the airplane gets itself stabilized in the climb. Ignore the leans. At some point, you'll want to level off. Take 10% of your climb rate and lead the level off by that many feet. You're probably climbing at something like 500 feet per minute on the VSI, so start levelling off about 50 feet below your target altitude. Inertia will carry the airplane up through the remaining 50 feet (you may actually need to use less than 10% if your airplane is a real dog). Anyway, the procedure for this pitch change is just as the one we used to get into the climb: pitch, power, trim. So, first use the AI to level the miniature airplane. If your airplane is a real pig, you may want to just let it accumulate airspeed at full power back up to almost 100 kts before you bring the power back to the cruise setting. But when that's done, trim off the control pressures. During the climb, use the DG, TC, and compass for information on how you're doing with holding heading. Fun!
Turns to headings are a little different than when visual. We always use a standard rate turn when under the hood. At normal cruise airspeed, this will usually end up being about 12 degrees of bank angle. Use the AI to establish the turn, then use the TC to monitor how well you're maintaining standard rate. Keep the tick marks on the TC lined up as well as you can -- this may mean adjusting your bank angle. As with a visual turn, lead your rollout by 50 percent of the bank angle. A standard-rate turn will seem slow. If your masochistic, you can do a standard rate turn with just the magnetic compass. Just turn at a rate of 3 degrees per second, and lead or lag your rollout as necessary (remember UNOS).
If you get distracted while flying on instruments, you can get yourself into an unusual attitude. This can be a nose-high attitude or more commonly, a nose-low banking attitude, but either way, you didn't intend to do it, and unless stopped, you can get into lots of trouble. If you look up from your chart and the instruments are all a jumble, just look at the ASI. If it's reading low, then your nose is pointed up. Use the AI to push the nose down to level, and simultaneously add full power -- you could be periously close to a stall. Use the TC to level the wings.
If the ASI said your airspeed was high and increasing, then pull your power back to idle and use the TC to level the wings. These actions will help to reduce any danger of bad load factors. The airplane is now diving straight ahead, so use the AI to smoothly pull the nose back up to a level attitude. Remember that the AI and DG may have tumbled in an unusual attitude, so keep your scan going. Because the altimeter and ASI are going to give you really valuable information about your pitch attitude.
After you can do straight and level flight, turns, climbs, and descents without much thought, you can start tracking VORs and NDBs.
When flying instruments, your workload is a lot higher than it is when you're visual. So don't tolerate much deviation in heading or altitude. If you do, errors will accumulate, and it will make it much harder to navigate, talk to ATC, play soduku, and chat with your passenger. Practice small corrections. Proper trim is essential.
All of this is moot without a thorough knowledge of how the instruments work. So prior to instrument flight, make sure you have a good no-shit understanding of what powers each instrument, how they get their information, and what sorts of errors are inherent in each instrument. Instrument flying is the most fun there is, for real.
