Pay attention that this page is under construction.
Information inside can be read but shall not be taken as input for any
exam or definite information.
The concept of weight and balance is critical in aviation industry.
Compliance with the known limits is very important relating to the
flight safety. Aircraft balance refers to the location of the center of
gravity (CG) of an aircraft. Operation with CG outside the approved
limits results in control difficulty.
Preflight planning should include a check of performance charts to
determine if the aircraft's weight may contribute to hazardous flight
The CG of a body is the theoretical point at which the entire weight of
that body is assumed to be concentrated. In a airplane, the CG is a
point at which the aircraft would balance if it were suspended atthat
The primary concern in balancing an aircraft is the fore and aft
location of the CG along the longitudinal axis. The CG is not
necessarily a fixed point. Its location depends on the distribution of
weight in the aircraft. The distance between the forward and back limits
for the position of the center for gravity or CG range is certified for
an aircraft by the manufacturer.\
On small airplanes and on helicopters, the CG location is identified as
being a specific number of inches or millimeters from the datum and
the CG range is identified the same way. On larger airplanes, the center
of gravity and its range are typically identified in relation to the
width of the wing (usually mean aerodynamic chord is used).
Each aircraft has a determed and precalculated weight and balance
references and numbers. Basically speaking it looks like this:
The actual location of the CG can be altered by many variable factors
and is usually controlled by the pilot:
Flying an aircraft that is out of balance can produce increased pilot
fatigue with obvious effects on the safety and efficiency of flight.
Adverse balance conditions affect flight characteristics in much the
same manner as those mentioned for an excess weight condition. Stability
and control are also affected by improper balance.
It is vital to comply with weight and balance limits established for all
Let's take a look onto standard Cessna 152 weight and balance sheet and
try to calculate weight and CG for different phases of flight.
Pilot weight: 160 lbs
Passenger weight: 140 lbs
Fuel required for flight: 15 gallons
Fuel consumption for flight: 7 gallons Baggage: 50 lbs.
Usually weight and balance sheet for general aviation consists of 2
parts: data table and CG graph (envelope). Our first step is to fill the
table with actual data.
1. Fill the table with weight data.
Use the conditions from above to fill the table and calculate total
2. Calculate the moments.
* Multiply each weight that was entered by its corresponding arm from
the "Arm" column and put the result in the "Moment" column.
3. Verify the numbers.
Verify that the total weight and CG for takeoff fall within the
4. Check weight and CG for landing.
During flight, fuel burn is normally the only weight change that takes
place. As fuel is used, an aircraft becomes lighter. Furthermore, fuel
moment also changes and it for sure affects total moment and CG
Summary: weight and CG is insight the limits during all phases of
flight, nor extremly forward or aft, so the flight could be safely