Weight & Balance Flashcards
How does air density affect aircraft performance?
Lower density means reduced performance - needs higher true airspeed for lift and engine produces less power
When air density decreases (due to higher temperature or lower pressure), aircraft performance suffers in two main ways. First, the airplane needs to achieve a higher true airspeed to generate enough lift. Second, the engine produces less power and thus less acceleration. These factors combine to require longer takeoff distances and reduce overall performance.
What is density altitude and why is it important?
The altitude in the standard atmosphere with the same density as current conditions, used to predict performance
Density altitude provides pilots with a practical way to understand air density effects on performance. Instead of working with complex density measurements, it expresses the current conditions in terms of a height in the standard atmosphere that would have the same density. High density altitude (indicating less dense air) means reduced aircraft performance, requiring longer takeoff distances and reducing climb performance.
How do you calculate pressure altitude from an altimeter setting?
Subtract actual altimeter setting from 29.92, multiply by 1000, add to field elevation
To calculate pressure altitude: Take 29.92 minus the current altimeter setting, multiply the difference by 1000, then add this to your field elevation. For example, with an altimeter setting of 30.12 at sea level: 29.92 - 30.12 = -0.20 × 1000 = -200 feet pressure altitude. Alternatively, in an aircraft, simply set the altimeter to 29.92 and read the indicated altitude.
What are the two components of takeoff distance and why are both important?
Ground roll and distance to clear obstacles - both needed for safety
Takeoff distance consists of ground roll (distance needed to lift off) and the distance needed to clear obstacles. Both are crucial because even if you have enough runway to lift off, you need additional distance to safely clear any obstacles at the end of the runway. This is why runway length alone isn’t sufficient information for takeoff planning.
What are the differences between AFM, POH, and PIM?
AFM is FAA-approved and aircraft-specific, POH includes AFM plus additional info, PIM is general reference
The Airplane Flight Manual (AFM) is FAA-approved, specific to an aircraft’s serial number, and must be in the aircraft. The Pilot’s Operating Handbook (POH) contains the AFM plus additional information in a standardized format. The Pilot’s Information Manual (PIM) is a general reference about a make/model that isn’t FAA-approved but is useful for study.
What performance information is required to be reviewed before flight per § 91.103?
Runway lengths at airports of intended use and takeoff/landing distance data
Federal Aviation Regulation § 91.103 requires pilots to become familiar with all available information before flight, specifically including runway lengths at airports of intended use and takeoff/landing distance data. This requirement ensures pilots verify their aircraft can safely operate at their intended airports under the expected conditions.
Why is it important to add safety margins to calculated takeoff/landing distances?
To account for variables like pilot technique, aircraft wear, and other real-world factors
Performance calculations assume perfect conditions and techniques. Safety margins account for variables like pilot experience and technique, aircraft wear and tear (may not perform like new), and other real-world factors that could affect performance. This conservative approach helps ensure safe operations despite inevitable variations from ideal conditions.
What are the main factors that increase required takeoff distance?
High temperature, low pressure, tailwind, and increased weight
Several factors increase required takeoff distance: high temperature and low pressure (which reduce air density and thus performance), tailwind (increases ground speed needed for takeoff), and increased weight (requires more lift). These factors can combine to significantly increase the runway length needed for safe operations.
How do you use the crosswind component chart?
Find angle between wind and runway, follow line to wind speed, read crosswind value
To use the crosswind component chart: 1) Find the difference between wind direction and runway heading, 2) Locate this angle on the chart, 3) Follow the line to the circle corresponding to wind speed, 4) Read straight down to find the crosswind component. This helps pilots determine if crosswinds are within their aircraft’s demonstrated limits.
How does temperature at altitude differ from temperature at the surface?
Temperature typically decreases by 2°C per 1000 feet up to the tropopause
When planning cruise performance, pilots must account for temperature changes with altitude. As covered in class, temperature typically decreases by 2°C per 1000 feet in standard conditions. This helps pilots estimate temperature at their cruise altitude when computing necessary performance data, like true airspeed and fuel burn, even when only surface temperature is known.
