## 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) - 15°C (ISA Temp)])

### Example:

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

### Calculate:

- 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 NOAA'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

## Climb Rate Required:

- 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:

- The general rule of thumb is to increase TAS by 2% for every 1,000' increase in the altitude
### Example:

- Indicated airspeed = 100 knots
- Altitude = 5,000'

### Formula:

- 5 * 0.02 = .1
- .1 * 100 = 10 knots
- 100 (IAS) + 10 = 110 knots TAS

## Conclusion:

- Many calculations are rules of thumb that are constantly handy
- 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

## Top of Climb:

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