## Units of Measure:

**Statute Mile:**the same as a standard mile as you would see driving a car**Nautical Mile:**defined as one minute of arc along a meridian of the Earth. Using the widely accepted WGS84 ellipsoid model, this averages a nautical mile to 6,076 feet (1,852 meters), or 1.15 statute miles

## Temperature Conversion:

- The U.S. is used to operating on the Fahrenheit scale for day to day life but aviation standard is Celsius
### Formula:

- °C = [(°F - 32) x 5/9]
- °F = [(°C x 9/5) + 32]

### Example:

- 70°F day

### Calculate:

- °C = ((70°F-32) x 5/9)
- You should come out with 21.1°C

### Chart

[Figure 1]- Start at your initial temperature on the Fahrenheit scale
- Move across until you hit the reference line
- Move down and read the temperature off of the bottom
- In this example it comes out to be roughly 22°C

### Table:

[Figure 2]- Find the temperature you need and read across the appropriate column
- Notice this table is more designed for Celsius to Fahrenheit but we still come out just over 21°C

## Crosswind Component:

- MOVED! See more about crosswinds on the crosswind landing page

## Short Field Takeoff Performance:

- MOVED! See more about short field takeoff performance on the Short Field Takeoff page

## Load Factor:

- MOVED! See more about crosswinds on the Accelerated Stalls page

## Stall Speed Banked:

- MOVED! See more about crosswinds on the Accelerated Stalls page

## True Vs. Magnetic North Course Conversion:

- Used primarily for flight planning when converting a chart (always true north) to a course to fly in the aircraft (magnetic north)
### Formula:

- "East is least, west is best"
- Magnetic Course (MC) = True Course (TC) - East Variation
- Magnetic Course (MC) = True Course (TC) + West Variation

### Example:

- True course is 270°
- Variation is 14° east

### Calculate:

- MC = 270° - 14°
- MC = 256°

## Mach Number:

- Most high-speed aircraft are limited to a maximum Mach number at which they can fly
- This is shown on a Machmeter as a decimal fraction

## Pressure Altitude:

- As altitude increases pressure will decrease in a standard atmosphere
### Formula:

- Pressure Altitude = [(29.92 - current baro) * 1000] + Current field elevation

### Example:

- Current baro: 29.82
- Field elevation: 500'

### Calculate:

- 29.92-29.82 = .10
- 0.10 * 1000 = 100'
- 100' + 500' = 600'

### Chart:

[Figure 4]- Using the chart on the right of the graph, look for the current altimeter setting
- To the right of it there will be an altitude in feet, and that is your conversion

Pressure/Density Altitude Conversion Chart

## Density Altitude:

- Pressure altitude corrected for non-standard temperature
- Used for performance calculations
### Formula:

- Pressure Altitude + (120 x [Outside Air Temperature (OAT) - (ISA Temp)])

### Example:

- Pressure Altitude = 600' (as calculated above)
- OAT: 10°C

### Calculate:

- ISA Temp (using standard Lapse rate of -2 degrees C per 1000 ft) is 14° C
- 600' + [120 * (10-14)]
- 600' + (-480) = 120'

### Chart:

[Figure 4]- From the temperature on the bottom move up to your pressure altitude
- Next move left and read your density altitude off the scale

- Other tools are available to help you calculate density altitude such as Pilot Friend's Density Altitude Calculator

## Cloud Bases:

- Used for VFR planning or when icing is a concern
- This is a very rough formula as cloud bases are not always flat and can change rapidly
### Formula:

- Temperature-Dew Point (°C) divided by 2 = Base of clouds
- Temperature-Dew Point (°F) divided by 4 = Base of clouds

### Example:

- Temperature: 10°C / 50°F
- Dew Point: 5 °C / 41°F

### Calculate:

- (10-5) ÷ 2 = 2,500' MSL
- (50-41) ÷ 4 = 2,250' MSL

## 60 to 1 Rule:

- One degree of course change will put you 1 NM off course after 60 NMs

## Takeoff & Landing Performance:

- Specific charts and their instructions are contained inside the pilot operating manual/pilot information manual for your aircraft
- The numbers provided are under specific conditions which will almost never apply exactly to your conditions
- Determine what your personal minimums are, and add a buffer to the performance calculated

## Determining Rate-of-Climb Requirements:

- Used to determine rate of climb for a given departure/climb out
### Formula:

- Ground Speed (GS) (knots) ÷ 60 * Climb Gradient (Feet Per Mile)

### Example:

- Ground Speed = 75 knots
- Climb Gradient Required = 200 feet per mile

### Calculate:

- 75 ÷ 60 * 200 = 280 feet per minute climb rate required

## Maneuvering Speed:

- Also referred to V
_{a} - More weight = more stable
### Formula:

### Example:

- Follow instructions given on section 6 of the POH

Maneuvering Speed Formula

## True Airspeed:

- MOVED! See more about crosswinds on the Airspeed Indicator page

## Top of Climb:

- MOVED! See more about crosswinds on the Flight Planning page

## Time to Travel Using a Whiz Wheel:

- Point the black arrow to match the expected ground speed
- Look for the distance to travel on the outer wheel
- Read time immediately below (inner scale) the number representing distance

## Ground Speed on Whiz Wheel:

- Line up distance over time (outer wheel over inner)
- Find the big black arrow, it is pointing to your ground speed
- Note that you will travel 10% of your speed in 6 minutes (6 min * 10 = 60 minutes)

## Fuel on Whiz Wheel:

- Point the big black arrow to the pounds per hour (burn rate)
- Read time off the inner wheel
- Look above time to get pounds burned in that time

## 60 to 1 Rule:

- The 60 to 1 rule is is a technique for establishing predictable pitch changes for climbs or descents and lead points for intercepting courses or arcs
- It allows the pilot to compute the pitch changes necessary when establishing an attitude during the control and performance concept of attitude instrument flying
- It reduces the pilot's workload and increases efficiency by requiring fewer changes and less guesswork
- It is an alternative to the TLAR (That Looks About Right) method of flying

- The 60-to-1 rule gives us a mathematical equation to help you figure out all these questions, but it is almost impossible to run these calculations and fly at the same time
- You need to use the formulas before you fly

- Find out what your turn radius is at cruise airspeed up high and at approach airspeed down lower; find out what a 1° pitch change will do to your VVI and remember those numbers
- The 60-to-1 Rule:
- 1° = 1 NM at 60 NM (60 NM from the station, there is 1 NM between each radial)
- 1° = 100 FT at 1 NM (1° climb or descent gradient results in 100 FT/NM)

- VSI Versus Pitch Change:
- We now know how to calculate the altitude gained or lost for each degree of pitch change over a given distance
- Throw in a time factor using True Airspeed (TAS) expressed in NM per MIN and we can relate this pitch change to a change in VSI
- First, lets convert speed to NM/MIN, since the 60-to-1 rule is based on TAS expressed in NM/MIN
- NM/MIN can be obtained easily from TAS as follows: NM/MIN = TAS/60
- Examples:
- 120 KTAS = 2 NM/MIN
- 150 KTAS = 2.5 NM/MIN

- If we don't have a TAS indicator, TAS can be computed from IAS
- TAS increases over IAS at the rate of 2% per 1,000 feet altitude increase
- So, the following equation could be used: TAS = IAS + (2% per 1,000 FT) X (IAS)
- Example: 3,000 FT; 150 KIAS
- TAS = 150 + (2% X 3) (150) = 150 + (.06)(150) = 159 KTAS

- Example: 3,000 FT; 150 KIAS
- Another easy but less accurate rule of thumb (best used above 10,000 feet) to determine TAS is: TAS = IAS + Flight Level (FL)/2 or "Add 5 kts per 1,000' to IAS"
- Example: FL 200; 175 KIAS
- TAS = 175 + (200/2) = 275 KTAS

- If one degree equals 100 ft/nm, then our VSI can be calculated numerous ways:
- VSI for 1° pitch change = NM/MIN X 100 FT
- VSI = (Pitch Angle) X (NM/MIN X 100)
- VSI = (Gradient) X (NM/MIN) = (FT/NM) X (NM/MIN)

- Example: FL 200; 175 KIAS

## Conclusion:

- Many calculations are rules of thumb that are constantly handy
- Note that while extrapolation or interpolation are skills pilots need to read charts, when you're parameters are off the chart, you're a test pilot, and performance in these regions should be treated as prohibited
- Reference material such as the: Pilot's Pocket Handbook: Flight Calculations, Weather Decoder, Aviation Acronyms, Charts and Checklists, Pilot Memory Aids and Pilot's rules of thumb: Rules of thumb, easy aviation math, handy formulas, quick tips can come in handy
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