Performance and Limitations

Question 1

Describe the composition of the atmosphere

Answer 1

78 percent nitrogen, 21 percent oxygen, 1 percent other gasses, such as argon and helium.

Question 2

What do we mean when we talk about “atmospheric pressure”?

Answer 2

It is the force exerted on a given area by the weight of the atmosphere. Essentially, the atoms and molecules in the air that comprise the atmosphere have mass, and therefore gravity pulls on them, meaning they have weight. Since air is a gas, this weight is applied in all directions, causing a force called air pressure when the molecules collide with something.

Question 3

What happens to air pressure as altitude increases, and why?

Answer 3

The weight of the atmosphere decreases, therefore the pressure decreases as well.

Question 4

By approximately how much? does the pressure decrease?

Answer 4

-1 inch of mercury (Hg) per 1,000ft of altitude gain.

Question 5

So if on a given day, sea level pressure is 30.00, what ambient air pressure would you expect to exist at 5,000ft MSL?

Answer 5

25.00, 5 inches fewer.

Question 6

Obviously the altimeter setting is the pressure in inches of mercury that gets entered into the Khollsman window. But what exactly does your current altimeter setting represent?

Answer 6

It’s the value to which the pressure scale in the Khollsman window is set so that the altimeter
indicates true altitude at field elevation.

Question 7

So does that mean that the altimeter setting represents the ambient air pressure at field elevation? In other words, does the altimeter setting equate with station pressure?

Answer 7

No, the altimeter setting represents what the baseline, sea level pressure would be in that
particular atmosphere at your location at that particular time. Put differently, the altimeter setting is station pressure (ambient air pressure at field elevation) corrected to mean sea level.

Question 8

If I stand outside with a barometer and it shows 29.72, is that the altimeter setting?

Answer 8

No (although it would be if you’re standing outside at sea level). From there you would have to adjust/ratio it down to sea level pressure, then it becomes your altimeter setting. So if you could drill a well below you down to sea level, then lower the barometer down to the bottom, whatever the barometer shows down there would be your altimeter setting.

Question 9

Say you are flying out of an airport located at sea level. You set 29.92 in the Kollsman window on a standard day. What altitude would the altimeter read?

Answer 9

0ft MSL.

Question 10

Say you are flying out of an airport located at sea level. You set 29.92 in the Kollsman window on a standard day. What altitude would the altimeter read?

If at that point you walk away from the plane, then return the next day when the ambient air pressure is 28.92 (instead of the 29.92 that it was the day before when you set the altimeter), what altitude would the altimeter show now?

Answer 10

It would show approximately 1,000ft because a pressure of 28.92 is found at 1,000ft in the standard atmosphere; the altimeter is showing your pressure altitude.

Question 11

Say you are flying out of an airport located at sea level. You set 29.92 in the Kollsman window on a standard day. What altitude would the altimeter read?

If at that point you walk away from the plane, then return the next day when the ambient air pressure is 28.92 (instead of the 29.92 that it was the day before when you set the altimeter), what altitude would the altimeter show now?

What would happen to your indicated altitude if at this point you adjusted the altimeter setting to 28.92?

Answer 11

It would show 0.

Question 12

If there were an airport a mile away that was built up on a 5,000ft MSL cliff, what would you expect that airport’s altimeter setting to be?

Answer 12

Close to the same: 28.92. The field elevation alone shouldn’t influence your altimeter setting (if the airport is located in the same climate area). Airports have barometers that measure the ambient air pressure (station pressure), then that pressure gets ratioed down to what it would be at sea level, and that becomes the altimeter setting.

Question 13

Say you are flying at a true altitude of 5,000ft MSL with an altimeter setting of 30.00. You fly into an area of low pressure where the altimeter setting should be changed to 29.00, except you don’t change it, it still shows 30.00. Will you be flying above or below the altitude shown on your altimeter? Explain why.

Answer 13

Below. At first, when the altimeter setting is accurate (as in, when we are flying in an atmosphere where the sea level pressure is actually 30.00), the pressure outside the plane at 5,000ft MSL is approximately 25.00 (30.00 - 5 inches, i.e. -1 inch for every 1,000ft of altitude gain). At this point, the accurately-set altimeter senses 25.00 and indicates our true altitude: 5,000ft. From here, as long as the altimeter setting doesn’t change, the altitude will always read 5,000ft when the altimeter senses a pressure of 25.00. Once the low pressure system moves in, the new atmosphere has a sea level pressure (the altimeter setting) of 29.00, meaning that the ambient air pressure of 25.00 that our altimeter is sensing (and we are tracking, because it corresponds to 5,000ft) is now found at a true altitude of 4,000ft (29.00 - 4 inches, i.e. -1 inch for each 1,000ft of altitude). Because our altimeter is essentially just a barometer that tracks pressure levels, it will track the 25.00 pressure down to a true altitude of 4,000ft. The altimeter is still using the old pressure scale where sea level pressure is 30.00, though, and on this scale the ambient air pressure of 25.00 will always correspond to 5,000ft. So 5,000ft MSL is still showing on the face of the instrument, and we are flying a true altitude 1,000ft below the altitude we think.

Question 14

So your altimeter is set for 30.00, your true altitude is 4,000ft, and indicated altitude is 5,000ft. Now let’s say that you adjust your altimeter to what it should be: 29.00. What altitude will the altimeter read now, and why?

Answer 14

4,000ft. By entering 29.00 into the Khollsman window, you recalibrate so that when the altimeter senses 29.00 it will indicate a 0 altitude, sensing 28.00 will indicate 1,000ft, 27.00 will indicate 2,000ft, 26.00 will indicate 3,000ft, and our present ambient air pressure of 25.00 will indicate 4,000ft.

Question 15

A cold front hits and the temperature drops severely. Are you now flying above or below the altitude indicated on the altimeter? Why?

Answer 15

Below. Cold air is denser than warm air, so the pressure levels become more compact; they get scrunched together, pulled down toward the earth. The pressure altimeter does not compensate for nonstandard temperature (we adjust for non-standard pressure when changing the altimeter setting, but there is no temperature equivalent). As a pilot, you will continue flying your desired indicated altitude, even though this altitude is now closer to the earth because the air is denser causing your pressure level to be lower (refer to figure 8-3 in the PHAK for a visual).

Question 16

When flying over terrain, what is the most dangerous combination of pressure and temperature? Why?

Answer 16

Low pressure, cold temperature. In this case, your true altitude will be lower than what’s indicated, so you’ll think you have more terrain clearance than in actuality.

Question 17

What expression can pilots use to help them remember that when pressures/temps are high, they will be flying higher than indicated; when pressures/temps are low, they will be flying lower than indicated?

Answer 17

“High to low, look out below; low to high, clear the sky.”

Question 18

What is the definition of “pressure altitude”?

Answer 18

The height above the standard datum plane (SDP).

Question 19

What does Standard Datum Plane mean?

Answer 19

A datum is just a reference point from which other things are measured. In this case, the SDP (just think datum) refers to an elevation and pressure used as a reference point. That elevation is sea level, and the pressure is 29.92. In the standard atmosphere, this pressure decreases 1 inch for every 1,000ft of altitude gain above the datum. So your pressure altitude is just your altitude above sea level when the pressure at sea level is 29.92. In other words, it is the altitude that the altimeter shows when the altimeter setting - that is, the sea level pressure - is 29.92. Put differently again, it is the altitude in the standard atmosphere that corresponds to the pressure the aneroid wafers are sensing inside the altimeter.

Question 20

What is pressure altitude used for?

Answer 20

To calculate performance and to fly flight levels.

Question 21

What are 3 methods a pilot can use calculate pressure altitude

Answer 21

1) Use the formula: (29.92 - altimeter setting)1,000 + field elevation; 2) set 29.92 into the Khollsman window and read the altitude shown on the altimeter; 3) use a pressure altitude table or graph, such as Figure 11-3 in the PHAK.

Question 22

What does air density (aka atmospheric density) mean?

Answer 22

It means, the ratio of the mass (or weight) of the air to the volume it occupies. I.e. higher density means more air molecules in a given space.

Question 23

What affects the density of the air, and how?

Answer 23

Pressure, temperature, and humidity. Pressure has a direct relationship with air density: since air is a gas, it can compress or expand; higher pressure naturally causes the air to compress, increasing density. Temperature has an indirect relationship with density: when air molecules are heated they become agitated and spread out, making them less dense. Humidity has an indirect relationship with density: water vapor molecules have a smaller mass (weigh less) than dry air molecules, i.e. wet air is less dense than dry air.

Question 24

In what 3 ways does less dense air (a higher density altitude) contribute to a reduction in performance?

Answer 24

1) Less power, because fewer air molecules are contributing to combustion in the engine(s); 2) less thrust, because the prop is throwing back fewer air molecules; 3) less lift, because fewer air molecules are striking the wings.

Question 25

What are the 3 definitions of “density altitude”?

Answer 25

1) Pressure altitude corrected for nonstandard temperature; 2) the altitude above sea level in the standard atmosphere at which a given atmospheric density is found; 3) the altitude at which the plane feels it is flying.

Question 26

What are some ways to compute density altitude?

Answer 26

Use the graph in the PHAK; use an E6B or a flight computer; or use the formula: 120(OAT - Standard Temp) + Pressure Altitude = Density Altitude.

Question 27

What kind of air density exists at a high density altitude?

Answer 27

Low.

Question 28

When would density altitude be the same as indicated altitude?

Answer 28

When temperature and pressure are standard, i.e. in the standard atmosphere.

Question 29

What happens to density altitude as temperature increases

Answer 29

Density altitude increases.

Question 30

If a low pressure system moves in, will this increase or decrease the density altitude?

Answer 30

Increase.

Question 31

What kind of performance would you expect while flying at a high density altitude?

Answer 31

Poor.

Question 32

The air is colder at higher altitudes . . . so shouldn’t the air be more dense, and therefore shouldn’t performance increase during climbs?

Answer 32

No, because at the same time, air pressure drops rapidly, and the density-reducing effect of the rapidly diminishing air pressure is dominant.

Question 33

How would you expect your takeoff roll and climb-out to be affected if taking off out of an airport with a high density altitude? Why?

Answer 33

Increased takeoff roll distance and a reduced rate-of-climb. Before lift-off, the plane must reach a faster groundspeed, requiring more runway; plus, the reduced power and thrust add a need for still more runway. As for rate-of-climb, the performance reduction caused by the thinner air will obviously translate to a lower climb rate (ft/min). Also, angle of climb will be reduced, because the higher density altitude translates to a faster true airspeed, and therefore the plane covers more distance horizontally over the ground for any vertical increase. In other words, the plane will climb at a shallower angle.

Question 34

When approaching to land at a high density altitude airport, what would you change about your approach speed and landing configuration, if anything?

Answer 34

Nothing.

Question 35

How would you expect your landing roll to be affected by a high density altitude, and why?

Answer 35

Landing roll would be longer, because the plane touches down at a faster groundspeed, so overcoming that momentum with the brakes takes longer. Also, the effects of any mistakes during the landing (like sideloading) would be more serious, again, due to touching down at a faster groundspeed.

Question 36

Would you expect takeoff performance to be degraded more by a low pressure system, a warm front, or high humidity? Why?

Answer 36

The warm front, because although pressure has the greatest effect on performance vertically in the atmosphere (because it drops so rapidly as altitude increases relative to the temperature drop), temperature has the greatest effect on density horizontally in the atmosphere (temperature often changes by as much as 40 degrees F over the course of even one day, whereas pressure generally stays within a window of about .1 or .2 inches). This is easily provable with the performance charts. As for humidity, although it does degrade performance, in general it’s effects are negligible in comparison with those of pressure and temperature.

Question 37

How does density altitude affect true airspeed (TAS) for any given indicated airspeed (IAS)?

Answer 37

The higher the density altitude, the higher the TAS in relation to IAS.

Question 38

By approximately what percent of your IAS does your TAS increase for every 1,000ft MSL of altitude gain?

Answer 38

2%.

Question 39

At 10,000ft MSL, approximately what would you expect your TAS to be if your IAS were 100kts?

Answer 39

120

Question 40

Say you’re setting up for turns-around-a-point and you see that your groundspeed is 5kts faster than your indicated airspeed. Does that mean you have a tail wind?

Answer 40

No, because it doesn’t factor in TAS. For instance, if you’re at 5,000ft MSL with an IAS for 100kts and your groundspeed is 105kts, that probably means you have about a 5kt headwind. This is because the TAS would be about 110kts at 5,000ft MSL, so if the GS is 5kts less, that would suggest a 5kt headwind.

Question 41

As density altitude increases what happens to the IAS at which the plane stalls?

Answer 41

Stays the same.

Question 42

As density altitude increases what happens to the TAS at which the plane stalls?

Answer 42

Increases.

Question 43

How and why does CG affect the following performance aspects of a properly trimmed airplane: Takeoff

Answer 43

a forward CG makes the airplane nose-heavy, which can make raising the nose more difficult during rotation. Pilots can alleviate this by applying a bit of nose-up trim prior to departure. An aft CG can make rotation too easy, potentially leading to a tail-strike during rotation (especially during the takeoff-roll portion of a soft field takeoff), or even a power on stall after lift off.

Question 44

How and why does CG affect the following performance aspects of a properly trimmed airplane: Stall speed:

Answer 44

Stall speed: a forward CG increases stall speed. This is because the plane is more nose-heavy, which requires the horizontal tail surface to produce more negative lift in order to level out the plane's pitch attitude. This added negative lift is a down force pushing down on the tail, making the plane heavier, increasing wing loading. To support this extra weight, the wings have to create more lift, and they do this by operating at higher angles-of-attack (AOA). This new, higher, AOA is closer to the critical AOA. So from here, as the plane slows and AOA slowly increases in order to maintain altitude, the plane will stall sooner, i.e. at a higher airspeed. An aft CG has the opposite effect.

Question 45

How and why does CG affect the following performance aspects of a properly trimmed airplane: Cruise speed

Answer 45

Cruise speed: as explained in the previous answer, a forward CG results in the tail producing more negative lift - a down force on the plane that the wings have to support by increasing their AOAs in order to produce more lift. So, both the tail and the wings are now producing more lift, and therefore more induced drag. This causes a slower cruise speed. An aft CG has the opposite effect.

Question 46

How and why does CG affect the following performance aspects of a properly trimmed airplane: Fuel burn:

Answer 46

Fuel burn: the extra drag caused by a forward CG (as discussed in the previous answer) means that the engine has to work harder - i.e. requires more power/throttle/combustion - to maintain a given airspeed. So more fuel gets burned. An aft CG has the opposite effect.

Question 47

How and why does CG affect the following performance aspects of a properly trimmed airplane: Stability:

Answer 47

Stability: a forward CG makes the plane more longitudinally stable. The plane’s longitudinal stability comes from the way it is designed with the CG located in front of wings/center of lift. To prevent the plane from naturally trying to nose down and descend all the time, the horizontal tail surface exists in order to produce negative lift, thereby raising the nose. Now, if there’s a pitch disturbance that causes the properly-trimmed airplane to nose down, the subsequent increase in airflow over the tail will cause an increase in negative lift, causing the nose to rise back up to its original, undisturbed position. Conversely, if the plane pitches up, less airflow over the tail (less negative lift) will cause the tail to rise and the nose to drop back down. The more forward the CG, the more nose-heavy the plane becomes, and therefore the more down force the tail produces to counter it. In other words, as the CG moves forward, the aircraft becomes more nose heavy and tail heavy, and it becomes harder to displace both the nose and the tail. Thus the plane becomes more longitudinally stable.

Question 48

How and why does CG affect the following performance aspects of a properly trimmed airplane: Controllability:

Answer 48

Controllability: stability and controllability have an inverse relationship: as stability increases, the control forces required to overcome that stability become greater, meaning controllability decreases. An unstable aircraft - one with an aft CG – requires lighter control inputs to control the airplane (i.e. is more responsive to pushing/pulling the yoke), and therefore is more controllable.

Question 49

How and why does CG affect the following performance aspects of a properly trimmed airplane: Stall recovery:

Answer 49

Stall recovery: after stalling, an aircraft loaded with a forward CG will have a nose that naturally tends to drop, aiding in stall recovery. An aft CG will have the opposite effect. On a slightly different note, it is also easier to cause a stall when loaded with an aft CG, because an increased AOA (one that could potentially exceed the critical AOA) will be achieved with less elevator control force.

Question 50

How and why does CG affect the following performance aspects of a properly trimmed airplane: Spin recovery

Answer 50

Spin recovery: recovering from a spin requires recovering from a stall, and a more forward CG helps to lower the nose of the airplane below the critical AOA. A forward CG also results in a longer arm between the CG and the rudder, which translates to more rudder authority. This added rudder authority aids in stopping the spinning rotation. An aft CG, on the other hand, could lead to a flat spin, making recovery extremely difficult or even impossible.

Question 51

How and why does CG affect the following performance aspects of a properly trimmed airplane: Landing:

Answer 51

Landing: a forward CG makes raising the nose during the roundout and flare more difficult, possibly causing a 3-point/flat landing that could lead to porpoising. An aft CG can make the plane more prone to floating and ballooning in the flare, possibly leading to a tail strike.

Question 52

How does a heavy weight affect the following: Takeoff:

Answer 52

Takeoff: takeoff distance increases as weight increases. A heavier plane has more inertia that needs to be overcome in order to accelerate the plane to its lift off speed. Imagine putting your car’s engine into a semi-truck; it’s going to take a lot longer to accelerate that semi-truck to a certain speed than it would your car.

Question 53

How does a heavy weight affect the following: Stall speed:

Answer 53

Stall speed: stall speed increases as weight increases. A heavier plane needs to produce more lift to counteract the extra weight, thus requiring a higher AOA (assuming a constant airspeed). To demonstrate this, imagine your plane cruising at 100kts. If the plane is loaded within limits, it will never stall at this speed. Now imagine suddenly adding 1,000lbs. You will have to increase AOA significantly in order to support this extra weight. Now add another 1,000lbs. You’ll have to increase AOA even more. At some point (provided the wings don’t snap . . .), if you keep adding weight and increasing AOA, the wings will exceed their critical AOAs and stall...at 100kts. This is much higher than the normal stall speed, clearly showing that stall speed increases along with weight. A light weight has the opposite effect.

Question 54

How does a heavy weight affect the following: Cruise speed:

Answer 54

Cruise speed: cruise speed decreases as weight increases. Heavier planes operate at higher AOAs, meaning more induced drag (the byproduct of the extra lift), causing slower cruise speeds for any given power setting. A light weight has the opposite effect.

Question 55

How does a heavy weight affect the following: Fuel burn

Answer 55

Fuel burn: fuel burn increases as weight increases. The extra drag caused by the higher AOAs (as discussed in the previous answer) means that the engine has to work harder - i.e. requires more power/throttle/combustion - to maintain a given airspeed. So more fuel gets burned. A light weight has the opposite effect.

Question 56

How does a heavy weight affect the following: Stability:

Answer 56

Stability: a heavy plane is more stable. This should be intuitive . . . just as you would have a harder time displacing a sumo wrestler than a small child, the air has a harder time displacing a heavy plane than a light plane. To explain this in more aerodynamic terms, a heavy plane has more inertia, and therefore requires more of a disturbance (be it an accidental control input or a gust of wind) to disrupt the plane from its undisturbed state. The opposite is true for light aircraft.

Question 57

How does a heavy weight affect the following: Controllability:

Answer 57

Controllability: a relatively heavy plane is generally going to be less responsive to control inputs because it has more inertia to overcome before it can react fully to the deflection of its controls - i.e. when heavy, more air must be deflected by a control surface in order to cause the same course-change effect.

Question 58

How does a heavy weight affect the following: Maneuverability

Answer 58

Maneuverability: maneuverability decreases as weight increases. This is because the wings on a heavier plane have to shoulder an increased load more rapidly as the plane gets maneuvered - exceeding the aircraft’s design load limits is therefore easier.

Question 59

How does a heavy weight affect the following: Maneuvering speed:

Answer 59

Maneuvering speed: maneuvering speed increases as weight increases. For a given airspeed, a heavy plane sits closer to its critical AOA, as discussed previously. So when a sudden load is applied (such as a forceful control input, severe turbulence, etc.) that causes the plane to pitch up, the heavy airplane will stall more readily; this stall unloads the aircraft and prevents exceeding its design load limits. A light airplane, on the other hand, sits at more of a level pitch attitude, so that when a load is applied causing the plane to pitch up, it doesn’t exceed its critical AOA and stall...instead, it continues pitching up, all the while taking on more and more load/stress.

Question 60

How does a heavy weight affect the following: Spin recovery:

Answer 60

Spin recovery: a spin recovery often involves slowly pulling out of a dive with rapidly increasing airspeed and G loads. A heavier plane will experience increased loads during such a recovery.

Question 61

How does a heavy weight affect the following: Landing:

Answer 61

Landing: a heavier plane carries more inertia with it into the landing roll-out. This means that the brakes have to work harder to stop the plane’s forward momentum, translating to a longer landing roll. A heavier plane also touches down with more force, which puts more stress on the gear, increasing the likelihood of impact-related gear and tire issues.

Question 62

In what ways should student pilots expect the plane to handle differently on their solo flights compared to their training flights?

Answer 62

The plane will be lighter and the CG will be farther aft, as there will be less weight at the pilot/passenger station (which is located ahead of the CG). Because of this, some degree of the effects described above for light weight/aft CG should be expected.

Question 63

How would you expect exceeding the CG and/or weight limitations to affect performance? Put differently, what might the performance ramifications be of operating an aircraft outside of its loading envelope?

Answer 63

First of all, I would be operating in uncharted territory (literally), so it would be impossible to know for sure what kind of performance to expect. If operating above max weight, safety margins are reduced, and over time the plane could experience excessive loads that degrade its structural integrity. If operating with an excessively forward CG, raising the nose during takeoff and landing could be difficult, or even impossible. An excessively aft CG could result in a critical degradation of longitudinal stability, producing very light control forces that make it easy to inadvertently overstress the aircraft. Recovery from stalls and spins might not be possible. When the CG is moved aft far enough to be aligned with the center-of-lift, the plane takes on neutral longitudinal stability. Moving the CG farther aft behind the center-of-lift causes a negative stability condition.

Question 64

Define the following weight and balance terms: Arm

Answer 64

Arm: the horizontal distance in inches from the reference datum line to the CG of an item. The algebraic sign is plus (+) if measured aft of the datum and minus (–) if measured forward of the datum.

Question 65

Define the following weight and balance terms: Basic empty weight (BEW):

Answer 65

Basic empty weight (BEW): the standard empty weight plus the weight of optional and special equipment that have been installed. We get this off of the official w+b; it is our starting weight for calculating w+b. It includes full engine oil and hydraulic levels and unusable fuel. It’s easier to think of BEW as the plane’s weight on the ramp before we add baggage/cargo, fuel, and people.

Question 66

Define the following weight and balance terms: Center of gravity (CG):

Answer 66

Center of gravity (CG): the point about which an aircraft would balance if it were possible to suspend it at that point. It is the mass center of the aircraft, or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated. The vertical, lateral, and longitudinal axes intersect through this point.

Question 67

Define the following weight and balance terms: Datum (reference datum):

Answer 67

Datum (reference datum): an imaginary vertical plane or line established by the manufacturer from which all measurements of arm are taken.

Question 68

Define the following weight and balance terms: Maximum ramp weight:

Answer 68

Maximum ramp weight: self-defining. It is greater than the takeoff weight due to the fuel that will be burned during taxi and run-up operations. Ramp weight may also be referred to as taxi weight.

Question 69

Define the following weight and balance terms: Moment:

Answer 69

Moment: the product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches. Total moment is the weight of the airplane multiplied by the arm of its CG. Think of moment as a force trying to rotate something around a point.

Question 70

Define the following weight and balance terms: Moment index:

Answer 70

Moment index: a moment divided by a constant such as 100, 1,000, or 10,000. The purpose of using a moment index is to simplify weight and balance computations for aircraft where heavy items and long arms result in large, unmanageable numbers.

Question 71

Define the following weight and balance terms: Standard empty weight:

Answer 71

Standard empty weight: aircraft weight that consists of the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the aircraft, including fixed ballast, hydraulic fluid, unusable fuel, and full engine oil. This is Basic Empty Weight minus optional equipment.

Question 72

Define the following weight and balance terms: Station:

Answer 72

Station: a location in the aircraft that is identified by a number designating its distance in inches from the datum. The datum is, therefore, identified as station zero. An item located at station +50 would have an arm of 50 inches. In layman’s terms, a station is a commonly used arm where we often add/remove weight.

Question 73

Define the following weight and balance terms: Useful load:

Answer 73

Useful load: the weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation (GA) aircraft only.

Question 74

What are the standard weights for AvGas, Jet A, Oil, and Water?

Answer 74

AvGas: 6lbs Jet A 6.8lbs Oil: 7.5lbs Water: 8.35lbs.

Question 75

What are the three different methods for calculating weight and balance, and how can you determine which to use for your aircraft?

Answer 75

Graph, table, and computational. Use the methods provided by the manufacturer in the POH/AFM.

Question 76

Do weight shift and weight removal math problems

Answer 76

see packet

Question 77

What happens to the CG as fuel is burned, and why?

Answer 77

The CG moves forward. This is due to the location of the fuel - and in particular the fuel’s weight - in relation to the CG. Because the fuel is stored slightly aft of the CG, as fuel burns there is less weight aft of the CG, causing the nose to tip forward, giving the plane a more forward CG.

Question 78

What are your aircraft’s maximum ramp, takeoff, and landing weights?

Answer 78

Ramp: N/A Takeoff: 2400 Landing: 2400

Question 79

Where exactly is the datum located on your aircraft?

Answer 79

Lower Portion of front face of firewall

Question 80

What does the white arc, as well as its upper and lower limits, represent on the airspeed indicator?

Answer 80

Full flap operating range. Upper limit is the maximum speed permissible with full flaps extended, 85KIAS Lower limit of the white arc is the stall speed in the landing configuration (flaps 30), Vso, 41 KIAS.

Question 81

What does the green arc, as well as its upper and lower limits, represent on the airspeed indicator?

Answer 81

Normal operating range. Upper limit is the maximum structural cruising speed, Vno, 128 KIAS. Lower limit is Vs1, stall speed in the clean configuration (flaps 0) 47 KIAS

Question 82

What does the yellow arc, as well as its upper and lower limits, represent on the airspeed indicator?

Answer 82

Caution range: 128-160. Operations here must be conducted with caution and only in smooth air.

Question 83

Red line.

Answer 83

Never exceed speed, Vne, 160

Question 84

At what weight are speeds calculated?

Answer 84

Maximum takeoff weight.

Question 85

What are your maneuvering speeds at 2550lbs, 2200lbs, and 1900lbs?

Answer 85

2400 - 97 kias 1950 - 89 kias 1600 - 80 kias

Question 86

What is the max window-open speed?

Answer 86

160 kias

Question 87

How is maneuvering speed (Va) marked on the airspeed indicator?

Answer 87

It isn’t.

Question 88

What is the definition of Va?

Answer 88

Defined two ways in the FAA sources: 1) the speed below which you can move a single flight control, one time, to its full deflection, for one axis of airplane rotation only (pitch, roll or yaw), in smooth air, without risk of damage to the airplane; 2) this is the maximum speed at which the limit load can be imposed (either by gusts or full deflection of the control surfaces) without causing structural damage. A simpler way to think of Va is that below this speed, the plane will be inclined to stall before it breaks.

Question 89

Does operating below Va provide structural protection against multiple full control inputs in one axis?

Answer 89

no

Question 90

Does operating below Va provide structural protection against full control inputs in more than one axis at the same time?

Answer 90

no

Question 91

What are some scenarios where you would slow below Va?

Answer 91

Turbulence/gusty conditions, or setting up for high load maneuvers such as accelerated stalls.

Question 92

Your aircraft’s current weight is 2400lbs. Its max gross weight is 2550lbs. It’s max Va is 105kts. What is its maneuvering speed?

Answer 92

The formula is: Plug V a @ Max Gross Weight * √(Y our Weight / Max Gross Weight). the numbers in and you end up with a Va of about 102.

Question 93

What is the RPM limit for takeoff and continuous operation?

Answer 93

2700 RPM

Question 94

What is the maximum allowable weight capacity for the baggage area (combination of areas A and B)?

Answer 94

120lbs

Question 95

What is the maximum number of occupants during a spin flight, and where must they be seated?

Answer 95

Max 2, and the rear seat must not be occupied.

Question 96

Which maneuver(s) are permitted in the utility category that are not permitted in the normal category?

Answer 96

Spins

Question 97

Why do you think spins are permitted in the utility category but not in the normal? The

Answer 97

airplane takes on higher loads more rapidly in spins. Also, a forward CG aids in spin recovery. Operating in the utility category ensures both a lighter weight and a forward CG in order to prevent any such loading/recovery issues.

Question 98

Are aerobatic maneuvers permitted in the utility category?

Answer 98

No, the POH does allow spins as long the plane is being operated in the utility category; however, the FAA has found that spins as part of either CFI training or upset recovery training do not qualify as aerobatic maneuvers: https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/i nterpretations/data/interps/2012/finagin-den-air%20-%20(2012)%20legal%20interpretation. pdf

Question 99

What is this aircraft’s CG range (the difference between its forward and aft CG limits)?

Answer 99

Forward 35 Aft 47.3

Question 100

What are your aircraft’s load limits in both the normal and utility categories with flaps up?

Answer 100

Flaps Up Normal category: +3.8 to -1.52. Flaps up Utility category: +4.4 to -1.76.

Question 101

What are your aircraft’s load limits in both the normal and utility categories full flaps?

Answer 101

+3.0

Question 102

Explain the Vg Diagram (figure 5-55 in the PHAK).

Answer 102

The Vg diagram shows the flight operating strength of the aircraft. This means that it shows how many Gs the aircraft can support for any given airspeed, as well as whether exceeding such Gs will cause a stall, structural damage, or structural failure. The green area represents the normal operating range on the airspeed indicator, the yellow represents the caution range, and the red represents never exceed speed. The aircraft represented by figure 5-55 would have a Vs of approximately 64kts because, at 1g, the plane stalls at this speed. Its maneuvering speed would be approximate 136kts because below this speed, if load factor is increased, the plane will stall, whereas above this speed, any increase in load factor could potentially lead to structural damage. This plane has a red line of 225kts, meaning even when operating with extremely low or non-existent load factors, structural failure could occur.

Question 103

Say you have limited runway distance to takeoff. Usually you would use flaps 10 for a short field takeoff, but you want to give yourself plenty of clearance so you decide to extend flaps 20. Is this legal?

Answer 103

No, flaps 10 is the max setting approved by the POH/AFM.

Question 104

Why do you think flap 20 takeoffs are not permitted?

Answer 104

The first 10 degrees of flap extension adds lift, as the flaps slide out on tracks and increase the overall size of the wing. The next 10 degrees of flap extension produces mostly drag as the flaps angle downward. This drag is helpful when approaching to land, not so much when trying to climb out and accelerate after takeoff.

Question 105

Under what circumstances may the plane be operated with the fuel selector valve handle on either the LEFT or RIGHT tank?

Answer 105

Level flight only. Not during takeoffs and landings.

Question 106

You turn the master and avionics switches on during your preflight and see on the fuel gauge that the tanks are topped off. Fuel-wise, are you now legal for a 2 hour VFR flight?

Answer 106

the preflight inspection on section 4 of the POH states that we must check the fuel visually

Question 107

Can the Terrain Awareness and Warning System (TAWS-B) be used to navigate around terrain and obstacles?

Answer 107

No, TAWS-B is intended merely as an aid in helping the pilot see and avoid.

Question 108

In terms of day, night, VFR, and IFR, what operations are permitted in your aircraft? How do you know?

Answer 108

the airplane as delivered is equipped for day VFR and/or IFR operations

Question 109

During your weather check you note that there are no icing PIREPs, but the temperature at field elevation is 1 degree Celsius and clouds are OVC004. Is an IFR takeoff permitted in your aircraft?

Answer 109

No, this qualifies as known icing conditions, as a reasonable and prudent pilot would expect structural ice to form on the aircraft during the flight. Section 2 of the POH/AFM prohibits flight into known icing conditions.

Question 110

What constitutes known icing conditions?

Answer 110

AIM: Known or observed or detected ice secretions: actual ice observed visually to be on the aircraft by the flight crew or identified by on board sensors.

Question 111

whats required for the formation of structural ice?

Answer 111

1) presence of visible moisture 2) aircraft surface temp at or below zero degrees CELCIUS mere presence of clouds isn't conductive to the formation of known ice & doesn't constitute known icing conditions

Question 112

what is the definition of max demonstrated crosswind ?

Answer 112

It is the velocity of the crosswind component for which adequate control of the airplane during takeoff and landing was actually demonstrated (using average abilities) during certification tests.

Question 113

What are your max demonstrated crosswind velocities for takeoffs and landings?

Answer 113

15 knots

Question 114

Is it legal to takeoff when the crosswind exceeds this speed?

Answer 114

Yes, it’s not a limitation.

Question 115

With what information must the PIC become familiar prior to every flight?

Answer 115

All available information. 91.103 specifies that this information must include (NWKRAFT): NOTAMs, weather, known traffic delays, runway lengths and takeoff/landing distances at all airports of intended use, alternatives, and fuel requirements.

Question 116

On a humid day with light rain at KIWA, you get cleared for an intersection departure on runway 30R at taxiway K. There is a 75ft crane about 500ft past the departure end of the runway. Your calculated short field takeoff distance over a 50ft obstacle is 2,000ft. Would you takeoff? Why or why not?

Answer 116

No, I would say, “Unable.” Runway distance available for takeoff at this intersection is about 2,500ft. The performance charts don’t factor in humidity, which will decrease performance and increase takeoff roll, as will the potentially wet runway surface. Also, the performance numbers are calculated with the engine in good condition, which may not be the case here, as our engine was manufactured years ago. Also, adding a 50% buffer to my calculations to account for any weight/weather inaccuracies brings my required distance to 3,000ft, which would be insufficient to clear the obstacle.

Question 117

Should you also factor in that the plane is being flown by a test pilot, so by an advanced pilot flying the plane perfectly?

Answer 117

The numbers were calculated “using average piloting techniques,” so not necessarily. I will add a buffer to my numbers for numerous other reasons, though.

Question 118

Is there any feature to this runway that would decrease takeoff distance?

Answer 118

Yes, it is downsloping.

Question 119

What procedure should you follow when using the alternate static air source?

Answer 119

Windows and vents closed. Cabin heat, cabin air, and defroster on maximum.

Question 120

The METAR says 18020KT . What crosswind would you expect if taking off on runway 30L?

Answer 120

Approximately 15 knots. To calculate this, be sure to first correct the METAR for magnetic variation (in the case of KIWA: -10 degrees), as winds on the METAR are oriented to true north, whereas runways use magnetic directions.

Question 121

Describe the crosswind takeoff procedure that you would use for this takeoff

Answer 121

Begin with full left aileron, elevator in the neutral, perhaps slightly forward position. As the airplane accelerates, keep the elevator in the neutral position and slowly roll out the left aileron so that as the nose rises off the ground, the ailerons are neutral.

Question 122

How should the rudders be utilized after lift off? Should you apply sufficient right rudder to maintain longitudinal alignment with the runway centerline during climb out? Why or why not?

Answer 122

No, once off the ground use only sufficient right rudder to maintain coordination. Let the plane crab into the wind. Using additional right rudder to maintain longitudinal alignment creates excess drag, decreasing climb performance.

Question 123

Why is it critical that the ailerons are neutralized as the plane lifts off the ground during such a crosswind takeoff?

Answer 123

Because otherwise the plane would enter a bank just as it lifts off the ground. Bank increases load factor, which increases drag and stall speed, decreasing performance. On the contrary, we are striving to maximize performance during this phase of flight.

Question 124

Now say that you are doing a short field takeoff at max weight on a grass runway with a 9kt headwind at a field elevation pressure altitude of 4,000ft. Temperature is 17 degrees. What distance is required to clear a 50ft obstacle?

Answer 124

At 10 degrees above standard at 4,000ft, the takeoff distance required is 2365ft. Per the notes below the table, decrease the distance by 10% for the headwind (-237), and increase the distance by 15% of the associated ground roll portion (1260*.15= 189) to account for the grass runway. So the required distance is 2317

Question 125

What mixture setting would you use for this takeoff?

Answer 125

Leaned for maximum RPM, because the pressure altitude is above 3,000ft.

Question 126

Would your rotation speed change if your weight were 2200 and2000 lbs?

Answer 126

Yes the new lift-off speed would be 54 and 51 KTS instead of 56 so rotation speed would be slightly below that.

Question 127

How would you expect your rate -of-climb to change if you were taking off into a sustained headwind?

Answer 127

A sustained headwind does not affect rate-of-climb.

Question 128

How would you expect your angle of climb to change if you were taking off into a sustained headwind?

Answer 128

The angle-of-climb would steepen. This is because groundspeed is slower, while rate-of-climb remains the same.

Question 129

If you had a strong headwind throughout your climb, how would you expect your time, fuel, and distance calculations to change?

Answer 129

Time and fuel should stay about the same, but the distance would shorten.

Question 130

How would you set the mixture if cruising at 6,000 ft, standard day, 2600 RPM?

Answer 130

2,600RPMs at 6,000ft is greater than 75% power = Should it be necessary to cruise at higher than 75% power, the mixture should not be leaned more than is required to provide peak RPM. POH P 4-16

Question 131

What cruise TAS would you expect at 4000 ft standard day 2500 rpm?

Answer 131

114 kts...

Question 132

What indicated airspeed would this be?

Answer 132

First use the E6B (or any applicable resource) to convert TAS to CAS using winds aloft info. Then use the Airspeed Calibration chart to calculate a conversion to KIAS, resulting in an IAS of 114kts.

Question 133

For the performance numbers to be correct when operating at power settings less than 75%, how must the mixture be leaned?

Answer 133

To achieve the recommended lean mixture fuel consumption figures shown in Section 5, the mixture should be leaned until engine RPM peaks and drops 25-50 RPM. At lower powers it may be necessary to enrichen the mixture slightly to obtain smooth operation. Should it be necessary to cruise at higher than 75% power, the mixture should not be leaned more than is required to provide peak RPM.

Question 134

The Range and Endurance graphs factor in a “45 Minutes Reserve.” What exactly does this mean?

Answer 134

Means there will be 45 minutes of fuel remaining upon reaching the distance and time limits given by the graphs.

Question 135

Do you need to factor in an extra safety margin for fuel burned during start, taxi, takeoff and climb?

Answer 135

No, it’s already factored in, per the notes.

Question 136

What exactly does your “total feet to clear 50 foot obstacle” calculation mean? In other words, where does this calculated distance start and end?

Answer 136

Starts at the point where you clear the 50ft obstacle, ends where the plane comes to a stop.