Lesson 7.4 Flight Planning & Performance Calculations

Lesson 7.4 – Flight Planning & Performance Calculations

Accurate flight planning and performance calculations are essential for safe cross-country flying and are heavily tested on the Private Pilot knowledge exam. You must be able to use the airplane’s Pilot Operating Handbook (POH) or Airplane Flight Manual (AFM) performance charts and compute basic weight-and-balance and fuel planning problems.

Reference:

FAA Pilot’s Handbook of Aeronautical Knowledge (PHAK), Chapters 10 & 11

Airplane Flying Handbook

Typical POH performance and weight-and-balance sections

Weight and Balance

Every airplane has a maximum weight limit and a center-of-gravity (CG) range that must be respected.

Key terms:

• Basic Empty Weight – Weight of the airplane with standard equipment and unusable fuel.

• Useful Load – Maximum weight minus basic empty weight (includes occupants, baggage, and usable fuel).

• Payload – Occupants and baggage (useful load minus usable fuel).

• Center of Gravity (CG) – The balance point of the loaded airplane. Must remain within the approved forward and aft limits.

You must be able to calculate total weight and CG location using the loading graphs or computational method in the POH. Exceeding maximum weight or operating outside the CG limits degrades performance and can make the airplane unstable or uncontrollable.

Performance Calculations

Takeoff and Landing Distance

Use the POH charts or tables to determine takeoff and landing distances. You must account for:

• Weight

• Wind (headwind or tailwind)

• Outside air temperature

• Pressure altitude (or density altitude)

• Runway surface and slope (when charts provide corrections)

High density altitude, high temperature, heavy weight, and tailwinds all increase takeoff and landing distances.

Climb Performance

POH charts show rate of climb and time/fuel/distance to climb under different conditions. Climb performance decreases with higher density altitude and higher weight.

Cruise Performance

Cruise charts give true airspeed, fuel flow, and range/endurance for different power settings, altitudes, and temperatures.

Fuel Planning

For VFR day flights you must carry enough fuel to fly to the first point of intended landing and then for at least 30 minutes.

For VFR night flights the reserve is 45 minutes.

Always calculate:

• Fuel required for taxi, takeoff, climb, cruise, and descent

• Reserve fuel

• Total fuel required versus fuel on board

Use expected groundspeed (true airspeed adjusted for wind) when calculating time and fuel for each leg.

True Airspeed and Density Altitude

• Indicated Airspeed (IAS) – What you read on the airspeed indicator.

• True Airspeed (TAS) – Actual speed through the air. TAS increases with altitude for a given indicated airspeed.

• Density Altitude – Pressure altitude corrected for non-standard temperature. High density altitude reduces all aspects of performance.

You must be able to use the E6B or POH charts to convert indicated airspeed to true airspeed and to determine density altitude.

Key Points for the Written Exam

• Know how to calculate weight and balance and determine if the airplane is within limits.

• Be able to read takeoff, landing, climb, and cruise performance charts.

• High density altitude, high weight, high temperature, and tailwinds all reduce performance.

• VFR day fuel reserve is 30 minutes; night reserve is 45 minutes.

• True airspeed is higher than indicated airspeed at altitude.

• Always use the performance data for the specific airplane you are flying.