Performance and Limitations

Introduction

Every aircraft, much like the pilots that fly them, has its unique strengths and weaknesses, which brings into focus the subject of aircraft performance and limitations.

Pilots must be familiar with the performance characteristics and limitations of the aircraft they are flying. This understanding extends from knowing how to compute takeoff, climb, cruise, and landing performance to understanding the aircraft’s structural, powerplant, and flight envelope limitations.

This lesson introduces performance charts, the principles that affect aircraft performance, and an understanding of the operational and structural limits of the aircraft. Pilots who don’t do the proper preflight planning or fail to comply with the airplane’s limitations are not exhibiting good judgment and may be in violation of 14 CFR 91.9 or 14 CFR 91.103.

Objectives

After this lesson, the learner will be able to:

Determine the airplane’s weight and balance condition.
Interpret performance charts supplied by the airplane manufacturer.
Describe the effects of atmospheric conditions on performance.
Determine if the airplane’s expected performance is within the parameters for safe flight.

Prerequisites

Performance calculations require the ability to determine the airplane’s current weight and balance condition. Review where to find weight and balance information in the AFM/POH and how to determine the center of gravity (CG).

Teaching Strategy

The performance section in the AFM/POH will generally provide charts in the sequence of a flight: takeoff, climb, cruise, descent, and landing. Go through each of these areas using a cross-country flight scenario. This will give the learner hands-on experience and put the knowledge into context.

Lesson Presentation

Appendices and Supplements

Aircraft Specific Training

How to locate performance data in the AFM/POH to include:
- Performance charts and tables
- Operating limitations
- Weight and balance data
- The airplane’s empty weight and CG location
Practice performance calculations for takeoff, climb, and landing

Risk Management

Inaccurate use of manufacturer’s performance charts, tables, and data
Exceeding airplane limitations
Possible differences between calculated performance and actual performance
Operating outside of CG limits
Shifting, adding, and removing weight

Scenario

You are preparing to leave the Sedona, AZ airport (KSEZ) after a weekend of hiking in the mountains. Your friends want to leave right after lunch, but you are concerned that the expected temperature is 30°C. The airplane is near its maximum gross weight with the passengers, luggage, and full fuel.

Determine if the airplane is capable of departing safely.

Case Studies

An overloaded Beech A36 Bonanza settles back towards the ground after takeoff and impacts terrain:

Aircraft: N1098F, Raytheon A36
Location: Cameron Park, CA
Date: August 30, 2007
News Report: https://youtu.be/UBdaCsCR9WE

A Boeing 737 overruns a snow-covered runway during landing at Chicago’s Midway Airport:

Aircraft: Southwest Airlines Flight 1248
Location: Chicago, IL
Date: December 8, 2005
Narrated Animation: https://youtu.be/jB1zYuA-3Ac

Resources

Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25):
- Chapter 11, Aircraft Performance
Aeronautical Information Manual (AIM):
- 4-3-6: Use of Runways/Declared Distances
- 4-3-8: Braking Action Reports and Advisories
- 4-3-9: Runway Condition Reports
- 7-6-7: Use of Runway Half-Way Signs at Unimproved Airports
FAASafety Course: Performance and Limitations
AOPA Safety Quiz: Aircraft Performance
AOPA Safety Quiz: Density Altitude
Koch Chart (https://takeofflanding.com)

Note: A Koch Chart can be used to visualize the effect of density altitude on takeoff, climb, and landing performance.

Schedule

Lesson Presentation (0:40)
Break (0:10)
Learner Practice (0:20)
Review and Assessment (0:20)

Equipment

Whiteboard, markers, and erasers
Notebook paper and pens
Calculator and flight computer (E6B)
Performance charts/graphs
Chart Supplements

Review and Assessment

This lesson concludes with a combined informal assessment and review of the main points.

Additionally, the instructor ensures:

All of the learner’s questions are resolved.
The learner is made aware of his or her performance and progress.

Completion Standards

This lesson is complete when the lesson objectives are met and the learner’s knowledge is determined to be adequate for the stage of training. Ultimately, the learner must meet or exceed the Airman Certification Standards.

Lesson Content

Required Preflight Action

Reference: 14 CFR 91.103

Before beginning a flight, the PIC must become familiar with all available information concerning that flight.

“All available information” includes:

For any flight:
- Runway lengths at airports of intended use.
- Appropriate takeoff and landing distance information.
For a flight under IFR or a flight not in the vicinity of an airport:
- Weather reports and forecasts.
- Fuel requirements.
- Alternatives available if the planned flight cannot be completed.
- Any known traffic delays of which the PIC has been advised by ATC.

Performance Regulations

References: 14 CFR 91.103, FSIMS 4-3-1

Pilots must conduct all flight operations within the aircraft’s limitations.

Aircraft limitations are published in:

The Airplane Flight Manual (AFM).
Placards or other markings.
Type Certificate Data Sheet (TCDS).
Supplements provided with aftermarket equipment.
Limitations of Supplemental Type Certificates (STC).
Maintenance manuals or instructions for continued airworthiness (ICA).

Advisory Information

Aircraft manufacturers may provide advisory information related to aircraft performance (e.g., wet runway landing distances). When advisory information is not placed in the limitations section, it is not a limitation. Pilots who do not observe such advice are not exhibiting good judgment.

Weight and Balance Calculations

Note: The most current weight and balance information in the AFM/POH should be used to obtain the basic empty weight and CG location. Old records are sometimes mistakenly used.

Computational Method: In the computational method, a weight/arm/moment calculation determines where the CG is.

General steps of the computational method:

List the weight of the empty aircraft, occupants, fuel, and baggage.
Calculate the moment for each item listed.
Find the total weight and total moment.
Divide the total moment by the total weight to determine the CG.

Graph Method: Some manufacturers provide graphs to determine the CG. The graphs are used to determine the moments. Then the CG is computed in the same manner as the computational method.

Center of Gravity Formula

Note: The location of the CG changes in flight. It may be due to fuel burn or extending and retracting the landing gear.

To find the location of the CG in inches aft of the datum, use the following formula.

CG = Total Moment ÷ Total Weight

Performance Charts

Information in the AFM/POH is not standardized among manufacturers. Some provide the data in tabular form, while others use graphs.

Performance data is usually based on:

Standard atmospheric conditions (59°F or 15°C, and 29.92″ Hg).
Pressure altitude or density altitude.

Some charts require interpolation for specific flight conditions. Interpolating means finding an intermediate value by calculating it from surrounding known values.

Example: To get the winds aloft at 7,500, the pilot needs to average the wind speeds and directions reported at 6,000′ and 9,000′.

Density Altitude

Aircraft performance is based on density altitude. High density altitude refers to thin air, while low density altitude refers to dense air. Regardless of the actual altitude of the aircraft, it performs as though it were operating at an altitude equal to the existing density altitude.

As density altitude increases:

Power Decreases: The engine takes in less air.
Thrust Decreases: A propeller is less efficient in thin air.
Lift Decreases: The thin air exerts less force on the airfoils.

Factors that Increase Density Altitude

Low Atmospheric Pressure: At a constant temperature, density decreases directly with pressure.
High Temperature: Increasing the temperature of a substance decreases its density.
High Humidity: Water vapor is lighter than air; consequently, air becomes less dense as its water content increases.

Calculating Density Altitude

Density altitude is defined as “pressure altitude corrected for nonstandard temperature variations.” Pressure altitude can be read off the altimeter when set to 29.92″ Hg.

Density altitude can be found by:

Using a flight computer.
Referring to a table and chart.

Correcting for Humidity

Note: Density altitude calculations are typically made using the dew-point because it is more accurate than using relative humidity.

Humidity is usually not considered an important factor in aircraft performance, but it is a contributing factor. Its effect can be determined using an online calculator.

Link: https://weather.gov/epz/wxcalc_densityaltitude

Example Calculation
Station Pressure: 22.22" Hg at 8,000'
Temperature: 80°F, Dew Point: 75°F
Density Altitude = 11,564'
With no humidity, the density altitude would be almost 500' lower.

When the temperature is greater than 5°C, a rule of thumb can be used: double the dew point in degrees Celsius and add a zero. Add the result to the density altitude.

 Example Calculation
24°C + 24°C = 480' Correction

High-Density Altitude Considerations for Takeoffs

Ensure the accuracy of weight and balance, takeoff distance, accelerate/stop distance, and climb rate calculations.
Add a significant safety margin (15% to 50%) to all performance calculations.
Lean the mixture, if equipped, for maximum horsepower.
Anticipate a lower-than-normal pitch attitude during the liftoff and climb because of reduced thrust.
Be aware that the airplane may “settle” after liftoff.
Know the location of high terrain and obstacles in the vicinity of the airport.

Performance on the Runway

Reference: AC 91-79

Runway Surface

Typically, performance chart information assumes paved, level, smooth, and dry runway surfaces. Any surface that is not hard and smooth increases the ground roll during takeoff. Runway surfaces for specific airports are noted in the Chart Supplements.

For small airplanes, the factors given below are often quoted in the flight manual as an alternative to data derived from testing or calculation.

Surface	Takeoff	Landing
Dry Grass	1.2	1.2
Wet Grass	1.3	1.6

Suggested Landing Distance Factors for Unimproved Runways

Note: Higher factors may be warranted if the runway is not smooth or the grass is long.

Runway Gradient

The gradient (slope) of a runway is the amount of change in runway height over the length. It is expressed as a percentage. A positive gradient indicates the runway height increases, and a negative gradient indicates the runway decreases in height.

Example: A 3% gradient means that for every 100′ of runway length, the runway height changes by 3′.

Runway gradient information is contained in the Chart Supplements. Depending upon the airplane’s manufacturer, runway slope may be accounted for in the AFM/POH performance data.

An upsloping runway impedes acceleration and results in a longer ground run during takeoff. However, landing on an upsloping runway typically reduces the landing roll. A downsloping runway aids in acceleration on takeoff, resulting in shorter takeoff distances. However, landing on a downsloping runway increases landing distances.

Rules of thumb:

An upslope increases takeoff distance by approximately 7% per degree.
A downslope reduces takeoff distance by approximately 5% per degree.
A downslope increases landing distance by approximately 10% per degree.

Safety Margins

The FAA recommends adding a safety margin of at least 15% to the planned takeoff and landing distances. Some pilots add 50% to their takeoff and landing calculations. The resulting distance should be within the runway length available and acceptable for obstacle clearance.

Takeoff Performance

References: AIM 4-3-10, AIM 7-6-7

The most critical conditions of takeoff performance are combinations of:

High gross weight
High-density altitude
Contaminated runways
Tailwinds
Uphill slopes
Short runways

Rules of thumb:

Abort the takeoff if no more than 70% of the takeoff speed is reached by 50% of the runway length (the “50/70” rule).
Add 50% to the planned takeoff distance over a 50-foot obstacle as a safety margin (the “50/50” rule).

Weight

The effect of gross weight on takeoff distance is significant and proper consideration of this item must be made in predicting the aircraft’s takeoff distance.

An increase in gross weight:

Requires a higher liftoff speed.
Decreases acceleration.
Increases the retarding force (drag and ground friction).

If the gross weight increases, more speed is required to get the aircraft airborne.

A 10% increase in takeoff gross weight causes:

An estimated 5% increase in takeoff velocity.
At least a 9% decrease in acceleration rate.
At least a 21% increase in takeoff distance (high thrust-to-weight ratio aircraft).
At least a 25% increase in takeoff distance (low thrust-to-weight ratio aircraft).

Wind

Rules of thumb:

A headwind that is 10% of the takeoff airspeed reduces the takeoff distance by approximately 19%.
A headwind that is 50% of the takeoff airspeed reduces the takeoff distance by approximately 75%.
A tailwind that is 10% of the takeoff airspeed increases the takeoff distance by approximately 21%.

Density Altitude

An increase in density altitude:

Requires a greater takeoff speed (true airspeed is higher than it would be at sea level).
Decreases acceleration due to decreased thrust.

Planning for Intersection Departures

Pilots should assess the suitability of intersection departures during their preflight planning. Pilots may ask ATC for the distance between the intersection and the runway end. However, the distance may not be the same as any published declared distances.

Climb Performance

An airplane can climb from one or a combination of two factors:

The excess power above that required for level flight. For example, an aircraft equipped with an engine capable of 200 horsepower, but using 130 horsepower to sustain level flight has 70 excess horsepower available for climbing.
KE can be traded-off for PE by reducing airspeed.

Factors that determine climb performance during a steady climb:

Airspeed: Too much or too little decreases climb performance.
Drag: Configuration of gear, flaps, cowl flaps, and propellers must be made with consideration for the least possible drag.
Power and Thrust: The rate of climb depends on excess power, while the angle of climb is a function of excess thrust.
Weight: Extra weight in the aircraft negatively affects performance.

Best Angle of Climb

The maximum angle of climb (AOC), obtained at VX, provides the greatest altitude gain over a certain distance. VX is maintained when it is necessary for an airplane to clear obstacles after takeoff.

For a given weight of an aircraft, the angle of climb depends on the difference between thrust and drag, or the excess thrust. The maximum angle of climb occurs where there is the greatest difference between the thrust available and the thrust required.

Maximum excess thrust occurs:

For a jet-powered airplane, at approximately the maximum lift/drag ratio (L/DMAX).
For a propeller-powered airplane, at an airspeed just above stall speed and below L/DMAX.

Best Rate of Climb

The maximum rate of climb (ROC), obtained at VY, provides the greatest altitude gain over time. VY is maintained when an airplane needs to reach the cruising altitude in the shortest time.

For a given weight of an aircraft, the climb rate depends on the difference between the power available and the power required, or the excess power. The maximum climb rate occurs where there is the greatest difference between the power available and the power required.

Maximum excess power occurs:

For a jet-powered airplane, at an airspeed above L/DMAX.
For a propeller-powered airplane, at an airspeed close to L/DMAX.

Effect of Weight

If weight is added to an aircraft, it must fly at a higher AOA to maintain a given altitude and speed. This increases the induced drag of the wings, as well as the parasite drag of the aircraft.

An increase in an aircraft’s weight produces a twofold effect on climb performance:

Increased Drag and Power Required: Reserve power available is reduced, which in turn, affects both the climb angle and the climb rate.
Reduced Rate of Climb: Less reserve thrust is available for climbing due to the increase in drag.

Effect of Altitude

As altitude increases, air density decreases, resulting in reduced available power. Airplanes with fixed-pitch propellers experience a reduction in RPM. Airplanes that are equipped with controllable propellers show a decrease in manifold pressure.

Speeds for the maximum rate of climb (VY) and maximum angle of climb (Vx) vary with altitude. As altitude increases, VY decreases and Vx increases until they converge at the aircraft’s absolute ceiling.

At the absolute ceiling, there is no excess of power, and only one speed allows steady, level flight. Consequently, the aircraft produces a zero rate of climb. The service ceiling is the altitude at which the aircraft cannot climb at a rate greater than 100 FPM.

Note: VY and Vx both increase with an increase in altitude as true airspeeds (TAS), but VY does so more slowly so that the two speeds converge. VY as an indicated airspeed (IAS) decreases with altitude.

Cruise Performance

In flying operations, the problem of efficient range operation of an aircraft appears in two general forms:

To extract the maximum flying distance from a given fuel load; or
To fly a specified distance with a minimum expenditure of fuel.

Maximum Range

Maximum range (distance) occurs where the ratio of speed to power/thrust required is greatest. The maximum range speed is dependent on the type of powerplant.

The maximum range speed occurs:

For a jet-powered airplane, above L/DMAX (near the typical cruise speed).
For a propeller-driven airplane, at L/DMAX (minimum drag condition).

A variation in weight alters the values of airspeed and power required to obtain the L/DMAX. Since fuel is consumed during cruise, the aircraft’s gross weight varies, and optimum airspeed, altitude, and power setting can also vary.

The following formula determines the specific range for any given flight condition. It is a useful calculation for comparing the efficiency and range of various aircraft.

Specific Range = NM per Hour ÷ Pounds of Fuel per Hour

Long-range cruise operations are normally conducted at the flight condition that provides 99% of the absolute maximum specific range. The advantage of such an operation is that 1% of the range is traded for 3 to 5% higher cruise speed.

Maximum Endurance

Maximum endurance (flying time) is obtained in a flight condition that requires the minimum amount of fuel flow to maintain steady, level flight.

The maximum endurance speed occurs:

For a jet-powered airplane, at L/DMAX (minimum drag and thrust condition).
For a propeller-driven airplane, at approximately 75% of L/DMAX (minimum power condition).

The following formula determines the specific endurance for any given flight condition.

Specific Endurance = Flight Hours per Hour ÷ Pounds of Fuel per Hour

Cruise Control

Cruise control of an aircraft implies that the aircraft is operated to maintain the recommended long-range cruise condition throughout the flight. As fuel is consumed, the aircraft’s gross weight decreases. The optimum airspeed and power setting decrease, or the optimum altitude increases.

Effects of Wind

Different theories exist on achieving maximum range when a headwind or tailwind is present. Many say that speeding up in a headwind or slowing down in a tailwind helps achieve the maximum range. While this theory may be true in many cases, there are variables in every situation.

Effects of Altitude

A flight conducted at a high altitude has a greater true airspeed (TAS) for the same indicated airspeed (IAS). Drag is the same, but the higher TAS causes a proportionately greater power required.

Range: An aircraft equipped with a reciprocating engine experiences very little, if any, variation of specific range up to its absolute altitude (not considering wind).

Endurance: Since the power required increases with altitude, the maximum endurance of a propeller-driven aircraft is achieved at sea level. If the airplane were over a flat surface, maintaining ground effect could reduce drag and extend the endurance.

Landing Performance

References: 14 CFR 91.1037, 14 CFR 121.195, 14 CFR 135.385, AC 91-79, SAFO 19001

The most critical conditions of landing performance are combinations of:

High gross weight
High-density altitude
Contaminated runways
Tailwinds
Downhill slopes
Less than maximum landing flaps
Short runways

Rules of thumb:

Increase the landing distance by 50% for a wet runway.
Increase the approach speed by 20% if ice is on the wings.
For every knot above the recommended approach airspeed at the runway threshold, the touchdown point is 100′ further down the runway.

Minimum Landing Distances Versus Ordinary Landings

A distinction should be made between the procedures for minimum landing distance and an ordinary landing roll with considerable excess runway available. Minimum landing distance is obtained by creating a continuous peak deceleration of the aircraft (maximum braking). On the other hand, an ordinary landing roll with considerable excess runway may allow extensive use of aerodynamic drag to minimize wear and tear on the tires and brakes.

Height Above Touchdown

Landing distances furnished in the AFM/POH are based on the landing gear being 50′ above the runway threshold. For every 10′ above the standard 50′ threshold crossing height, the landing distance increases by approximately 200′.

Weight

The minimum landing distance varies in direct proportion to the gross weight. An increase in gross weight requires a faster approach speed and requires more effort to decelerate to a stop after landing.

A 10% increase in gross weight causes:

An estimated 5% increase in landing velocity.
An estimated 10% increase in landing distance.

Density Altitude

An increase in density altitude increases the landing speed. The aircraft at altitude lands at the same indicated airspeed (IAS) as at sea level, but the true airspeed (TAS) is greater because of the reduced density.

Because a given IAS corresponds to a higher TAS at higher density altitudes, pilots are sometimes “tricked” by visual cues and fly slower than they should.

The approximate increase in landing distance with altitude is approximately 3.5% for each 1,000′ of altitude. At 5,000′, the required landing distance is 16% greater than at sea level.

Excessive Airspeed and Wind

The speed (acceleration and deceleration) experienced by any object varies directly with the imbalance of force and inversely with the object’s mass.

Example: An airplane on the runway moving at 75 knots has four times the energy it has when moving at 37 knots. The airplane requires four times as much distance to stop.

Rules of thumb:

An increase in the approach speed by 10% increases the landing distance by 20%.
For every 10 knots of tailwind, increase the landing distance by at least 21%.

Excessive speed upon touchdown places a greater load on the brakes because of the additional kinetic energy. Also, excessive speed increases lift in the normal ground attitude after landing, which reduces braking effectiveness.

Aviation Rules of Thumb

Barometric Pressure

Pressure decreases at a rate of 1″ Hg per 1,000′ of altitude gain. The standard surface pressure at sea level is 29.92″ Hg.

Pressure Altitude

The pressure altitude can be determined by:

Setting the barometric scale of the altimeter to 29.92 and reading the indicated altitude.
Applying a correction factor to the indicated altitude according to the reported altimeter setting.

Example:

Field Elevation = 300′
Altimeter Setting = 30.02″ Hg
Pressure Altitude = 200′

If the local altimeter setting is greater than 29.92 inches, pressure altitude is lower than field elevation.

Density Altitude

A normally aspirated engine produces 3% less power for every 1,000′ of density altitude.

Density altitude increases (or decreases) 102′ for every 1°C the temperature varies from standard.

For every 10°F above standard temperature at an airport’s elevation, add 600′ to the field’s elevation.

Correct Density Altitude for Humidity

If the temperature is greater than 5°C, double the dew point in degrees Celsius and add a zero. Add the result to the density altitude.

Example: 24°C + 24°C = 480′ Correction

Altimeter Errors

“From hot to cold, look out below.”

When the air temperature is warmer than standard, the altimeter will indicate a lower altitude than actually being flown. When the air temperature is colder than standard, the altimeter will indicate a higher altitude than actually being flown.

“From high to low, look out below.”

When flying from an area of higher pressure to an area of lower pressure without resetting the altimeter, the aircraft is flying at a lower altitude than indicated. If flying from an area of low pressure to an area of high pressure without resetting the altimeter, the aircraft is flying a higher altitude than indicated.

Temperature Lapse Rate

Temperature decreases at a rate of 3.5°F (2°C) per thousand feet.

True Airspeed

True airspeed increases by 2% for every 1,000′ of altitude.

Clouds and Weather

When flying over the top of a severe thunderstorm, the cloud should be over-flown by at least 1,000′ for every 10 knots of wind speed.

To find the height of the cloud bases, use the following formula (the temperature is in degrees Fahrenheit).

((Temperature – Dew Point) ÷ 4.4) × 1,000

Airspeed Calculations

Maneuvering Speed = VS1 × √Positive Limit Load Factor

Maneuvering speed (VA or VO) decreases 2 knots for every 100 pounds below max gross weight.

Best rate of climb speed (VY) decreases 1/2 knot for every 1,000′ of density altitude gained.

Best angle of climb speed (VX) increases 1 knot for every 1,000′ of density altitude gained.

Best glide speed (VBG) decreases 1/2 to 1 knot for every 100 pounds under max gross weight.

Rotation Speed (VR) = 1.15 × VS0

Dynamic Hydroplane Speed = 8.6 × √(Tire Pressure)

Airspeeds at Reduced Weights

Speeds published in the AFM/POH at max gross weight (e.g., maneuvering, stall, and approach) can be reduced for the current weight using the following formula or rule of thumb.

VNEW = VOLD × √(Current Weight ÷ Max Gross Weight)

VNEW is the calculated speed for the current weight.
VOLD is the AFM/POH speed at the max gross weight.

As a rule of thumb, these speeds decrease 1% for every 2% reduction in gross weight.

Defined Minimum Maneuvering Speed

A defined minimum maneuvering speed (DMMS) provides a margin above stall speed during turning flight. It is essentially a 30% buffer above the clean stall speed (VS1) in a 30° bank.

DMMS = VS1 × 1.4

Attitude Flying

The Primary Rule of Attitude Flying
Attitude + Power = Performance

Use one-half of the bank angle to begin a rollout to a heading. For a 30° bank, begin the rollout 15° early.

Lead a level off from a climb or descent by 10% of the vertical speed. If the climb rate is 500 FPM, initiate the level-off 50′ early.

For altitude deviations of less than 100′, use a half-bar-width correction. For errors over 100′, use a full-bar-width. An alternate method is to establish a change rate of twice the altitude deviation, not to exceed 500 FPM. If the altitude is off by 100′, the rate of return should be 200 FPM.

Takeoff Distance

Increase the takeoff distance by 15% for every 1,000′ of density altitude above sea level (12% with a constant speed prop).

Increase the takeoff distance by 7% for each degree of runway upslope. Reduce the takeoff distance by 5% for each degree of runway downslope.

Increase the takeoff distance by 10% for every two knots of tailwind.

Abort the takeoff if no more than 70% of the takeoff speed is reached by 50% of the runway length.

Add at least 15% (50% recommended) to the planned takeoff distance as a safety margin.

Climb Gradients

Climb Rate in FPM = (Ground Speed ÷ 60) × Climb Gradient

Climb Gradient as a Percentage = (Rise ÷ Run) × 100

Note: The “rise” and the “run” are in feet. There are approximately 6,076 feet in one nautical mile.

Approach and Landing

3° Rate of Descent = Ground Speed × 5

For every knot above the recommended approach airspeed at the runway threshold, the touchdown point will be 100′ further down the runway.

For every 10′ above the standard 50′ threshold crossing height, increase the landing distance required by 200′.

For every 10% reduction in weight, reduce the approach speed published at the max gross weight by 5%.

Increase the landing distance by 50% for a wet runway.

Increase the approach speed by 20% if ice is on the wings.

Increase the landing distance required by 21% for every 10 knots of tailwind.

Add at least 15% (50% recommended) to the planned landing distance as a safety margin.

Mixture Settings

Engine Start: Full-rich, unless the engine is flooded
Taxi: Lean for max RPM
Takeoff < 4,000′ Density Altitude: Full-rich
Takeoff > 4,000′ Density Altitude: Lean for max RPM
Climb > 4,000′ Density Altitude: Lean for max RPM
Cruise: Lean per the AFM/POH performance charts
Descent: As necessary to produce a smooth running engine
Landing: Appropriate setting for a go-around

Maximum Range and Endurance

Max Endurance Speed (Fixed Gear) = 1.2 × VS
Max Endurance Speed (Retractable Gear) = 1.3 × VS
Max Range Speed (Fixed Gear) = 1.5 × VS
Max Range Speed (Retractable Gear) = 1.8 × VS

Maximum range speed changes with wind:

Increase the speed by half of the headwind.
Decrease the speed by half of the tailwind.

Reciprocal Headings

To find a reciprocal heading, add 200 and subtract 20, or subtract 200 add 20.

Standard Rate Turn

Bank Angle = (TAS ÷ 10) + 5

Sectional Charts

The width of a finger equals 5 NM on a Sectional Chart for the average person.

The distance from the tip of the thumb to the knuckle equals 10 NM on a Sectional Chart for the average person.

Planned Descent Point

The following formula is used to calculate a PDP in NM. The threshold crossing altitude (TCA) is the TDZE plus the TCH (typically around 50′). The resulting distance is the PDP in NM from the runway.

PDP = (MDA – TDA) ÷ 318

To calculate the PDP in minutes and seconds, use the following formula. Subtract the resulting time from the time required to fly the approach.

PDP = (MDA – TDA) ÷ 10

3° Glidepath

To find the proper altitude at any point along on a 3° glidepath, multiply the distance in nautical miles from the threshold by 300. At 10 NM the aircraft should be 3,000′ above the TDZE, at 5 NM 1,500′, and at 1 NM 300′.

To find the proper rate of descent on a 3° glidepath, multiply the groundspeed by 5. At 120 knots, the descent rate should be 600 FPM.

Crosswind Components

Example: A 30° wind results in a crosswind component of 50%.

Common Aviation Units and Conversions

Length

1 Degree of Latitude
= 60 nautical miles
= 69 statute miles
= 11 kilometers (km)

1 Nautical Mile
= 6,076 feet (ft)
= 1.15 statute miles
= 1.85 kilometers
= 1,852 meters (m)

1 Statute Mile
= 5,280 feet
= 0.87 nautical mile
= 1.61 kilometers
= 1,609 meters

1 Foot
= 12 inches (in)
= 30.5 centimeters (cm)
= 0.3048 meter

Area

1 Square Foot
= 144 inches2
= 0.093 meter2

Weight

1 Ounce
= 28 grams (g)
= 480 grains (gr)

1 Pound
= 16 ounces (oz)
= 448 grams
= 0.4536 kilogram (kg)

1 Slug
= 14.594 kilograms
= 32.2 pounds (lbs)

Speed

1 Knot
= 1 nautical mile per hour
= 1.15 statute miles per hour
= 101 feet per minute
= 0.51 meter per second
= 1.85 kilometers per hour

1 Mile Per Hour
= 1 statute mile per hour
= 0.87 knot
= 0.45 meter per second
= 1.61 kilometers per hour

Volume

1 Cubic Foot (ft3)
= 1,728 inches2
= 0.028 meters3

Pressure

Sea-Level Standard Atmosphere
= 29.92 inches of mercury (Hg)
= 1013.25 millibars (mb) or hectopascals (hPa)
= 14.7 pounds per square inch (lbs/in2)
= 59°F
= 15°C

1 Inch of Mercury
= 0.491 pounds per square inch
= 33.864 millibars or hectopascals

1 Millibar
= 1 hectopascals (equivalent units)
= 0.0295 inch of mercury

Temperature

°C to °K
°C + 273

°C to °F
(°C × 1.8) + 32

°F to °C
(°F – 32) × 5/9

Crosswind and Headwind Component Chart

Example Problem
20 knot wind at a 60° angle to the runway
Solution
18 knot crosswind component
10 knot headwind component

Density Altitude Chart

Example Problem
Pressure altitude is 9,500' and the temperature is -8°C
Solution
Density altitude is 9,000'

ICAO Standard Atmosphere

Altitude (Feet)	Density Ratio (σ)	√σ	Pressure Ratio (δ)	Temperature (°F)	Temperature Ratio (θ)	Speed of Sound (Knots)	Kinematic Viscosity
0	1.0000	1.0000	1.0000	59.00	1.0000	661.7	.000158
1,000	0.9711	0.9854	0.9644	55.43	0.9931	659.5	.000161
2,000	0.9428	0.9710	0.9298	51.87	0.9862	657.2	.000165
3,000	0.9151	0.9566	0.8962	48.30	0.9794	654.9	.000169
4,000	0.8881	0.9424	0.8637	44.74	0.9725	652.6	.000174
5,000	0.8617	0.9283	0.8320	41.17	0.9656	650.3	.000178
6,000	0.8359	0.9143	0.8014	37.60	0.9587	647.9	.000182
7,000	0.8106	0.9004	0.7716	34.04	0.9519	645.6	.000187
8,000	0.7860	0.8866	0.7428	30.47	0.9450	643.3	.000192
9,000	0.7620	0.8729	0.7148	26.90	0.9318	640.9	.000197
10,000	0.7385	0.8593	0.6788	23.34	0.9312	638.6	.000202
15,000	0.6292	0.7932	0.5643	5.51	0.8969	626.7	.000229
20,000	0.5328	0.7299	0.4595	-12.32	0.8625	614.6	.000262
25,000	0.4481	0.6694	0.3711	-30.15	0.8281	602.2	.000302
30,000	0.3741	0.6117	0.2970	-47.98	0.7937	589.5	.000349
35,000	0.3099	0.5567	0.2353	-65.82	0.7594	576.6	.000405
36,089*	0.2971	0.5450	0.2234	-69.70	0.7519	573.8	.000419
40,000	0.2462	0.4962	0.1851	-69.70	0.7519	573.8	.000506
45,000	0.1936	0.4400	0.1455	-69.70	0.7519	573.8	.000643
50,000	0.1522	0.3002	0.1145	-69.70	0.7519	573.8	.000818

* The Troposphere

Braking Action Codes and Definitions Matrix

Assessment Criteria		Control/Braking Assessment Criteria
Runway Condition Description	RwyCC	Deceleration or Directional Control Observation	Pilot Reported Braking Action
Dry	6	—	—
Frost Wet (Includes damp and 1/8 inch depth or less of water) 1/8 inch depth or less of: Slush Dry Snow Wet Snow	5	Braking deceleration is normal for the wheel braking effort applied and directional control is normal.	Good
-15°C and colder OAT: Compacted Snow	4	Braking deceleration or directional control is between Good and Medium.	Good to Medium
Slippery when wet (wet runway) Dry snow or wet snow (any depth) over compacted snow Greater than 1/8 inch depth of: Dry Snow Wet Snow Warmer than -15°C outside air temperature: Compacted snow	3	Braking deceleration is noticeably reduced for the wheel braking effort applied or directional control is noticeably reduced.	Medium
Greater than 1/8 inch depth of: Water Slush	2	Braking deceleration or directional control is between Medium and Poor.	Medium to Poor
Ice	1	Braking deceleration is significantly reduced for the wheel braking effort applied or directional control is significantly reduced.	Medium to Poor
Wet ice Slush over ice Water over compacted snow Dry snow or wet snow over ice	0	Braking deceleration is minimal to non-existent for the wheel braking effort applied or directional control is uncertain.	Nil

Reference: AIM 4-3-9

Notes:

The unshaded portion of the RCAM is associated with how an airport operator conducts a runway condition assessment.
The shaded portion of the RCAM is associated with the pilot’s experience with braking action.
Runway condition codes, one for each third of the landing surface, represent the runway condition description as reported by the airport operator (e.g., 4/3/3).
A “NIL” braking condition report requires closure of the affected runway.
Controllers will not issue runway condition codes when all 3 segments of a runway are reporting values of 6.

V-Speed Quick Review

General Information

V-speeds are airspeeds defined for specific maneuvers and configurations. They may be stated in MPH or knots, and as calibrated airspeeds (CAS) or indicated airspeeds (IAS). Newer AFM/POHs use knots indicated airspeed (KIAS).

The "V" stands for vitesse, a French word for speed or rate.

Unless otherwise noted in the AFM/POH, V-speeds apply to sea level, standard day conditions at maximum takeoff weight.

Conditions that can affect the value of V-speeds include:

Aircraft weight and configuration
Atmospheric conditions (e.g., altitude and temperature)
Runway conditions (e.g., contaminated runway)

V-Speeds on the Airspeed Indicator

Lower Limit of White Arc – Stall Speed in the Landing Configuration (VSO): In small aircraft, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down).

Lower Limit of Green Arc – Stall Speed in a Specific Configuration (VS1): For most airplanes, this is the power-off stall speed at the maximum takeoff weight in the clean configuration (gear up, if retractable, and flaps up).

Note: “Stall speed” can be misleading. A stall can occur at any airspeed, in any attitude, with any power setting.

Upper Limit of White Arc – Maximum Flap Extended Speed (VFE): The maximum speed for operating with the flaps extended. Some aircraft allow partial flap extensions above the airspeed indication (refer to the AFM/POH limitations).

Upper Limit of Green Arc – Maximum Structural Cruising Speed (VNO): The maximum speed that can be flown safely fly in smooth air. Flight above VNO should only be conducted cautiously. Structural damage can occur if rough air is encountered beyond this speed.

Red Line – Never-Exceed Speed (VNE): The absolute maximum speed. Structural damage or failure can occur beyond this speed.

Other V-Speeds (Not on the Airspeed Indicator)

Rotation Speed (VR): The speed at which the pilot makes a control input, with the intention of lifting the airplane out of contact with the runway or water surface. To prevent an inadvertent stall during takeoff, VR cannot be less than VS1.

Maximum Landing Gear Extended Speed (VLE): The maximum speed for operating with the landing gear extended. A related speed is VLO, which is the maximum speed for operating (extending or retracting) the landing gear.

Design Maneuvering Speed (VA): The speed below which the pilot 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. VA decreases as the airplane’s weight decreases.

Best Angle of Climb Speed (VX): The speed that results in the greatest altitude over the shortest distance. Pilots use VX during a short-field takeoff to clear obstacles in the departure path.

Best Rate of Climb Speed (VY): The speed that results in the greatest altitude gain over the shortest period of time. Pilots use VY as the normal climb speed after takeoff.

Best Power-Off Glide Speed (VG/VBG): The speed that maximizes gliding distance. VG and VBG are commonly used but are not official V-speeds.

V-Speed List

Reference: 14 CFR 1.2

V1	Maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes) to stop the airplane within the accelerate-stop distance. Also the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.
V2	Takeoff safety speed: The speed at which the aircraft may safely be climbed with one engine inoperative (OEI).
VA	Design maneuvering speed
VB	Design speed for maximum gust intensity
VG/VBG	Best power-off glide speed: Provides the greatest flight distance available (VG and VBG are not official V-speeds)
VC	Design cruising speed
VD	Design diving speed
VF	Design flap speed
VFE	Maximum flap extended speed
VH	Maximum speed in level flight with maximum continuous power
VLE	Maximum landing gear extended speed
VLO	Maximum landing gear operating speed
VLOF	Liftoff speed
VMC	Minimum control speed with the critical engine inoperative (commonly used instead of VMCA)
VMCA	The minimum speed that the aircraft is still controllable with the critical engine inoperative while the aircraft is airborne
VMCG	The minimum speed that the aircraft is still controllable with the critical engine inoperative while the aircraft is on the ground
VMO/MMO	Maximum operating limit speed (knots or mach)
VMU	Minimum unstick speed
VNE	Never-exceed speed
VNO	Maximum structural cruising speed
VO	Operating maneuver speed: At or below this speed, the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits.
VR	Rotation speed
VREF	Reference landing speed
VS	Stalling speed or the minimum steady flight speed at which the airplane is controllable
VS0	Stalling speed or the minimum steady flight speed in the landing configuration
VS1	Stalling speed or the minimum steady flight speed obtained in a specific configuration
VSSE	Safe, intentional one-engine-inoperative speed: The minimum speed at which to perform intentional engine cuts in flight.
VX	Best angle of climb speed: The speed that will produce the greatest altitude over the shortest ground distance.
VXSE	Best angle of climb speed with one-engine-inoperative
VY	Best rate of climb speed: The speed that will produce the greatest altitude in the shortest time.
VYSE	Best rate of climb speed with one-engine-inoperative

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Sunday, January 7, 2024