Next to a good preflight plan and weather report is a thorough Weight & Balance calculation. Weight & balance is a matter of serious concern to all pilots as well as many other people involved in the flight. The pilot has to personally assume the responsibility (and by law) because he has control over both the loading and fuel management, the two variable factors which can change both total weight & balance. This information is available to the pilot in the form of aircraft records, operating handbooks and placards in baggage compartments and or fuel caps. The owner of the aircraft has the responsibility to make sure that up to date information is available to the pilot.

The Weight & Balance form we present can be used for this purpose. It is very important to realize that any aircraft (yes, experimental aircraft too) which is out of balance or overweight is dangerous to fly. Not to mention deadly.
So please be very, very serious about this.

Weight & Balance Background

Before we dive into the W&B calculations we need to do some theory behind the subject. I believe that having a good background helps understanding the importance of flying an airplane which is not overweight or out of balance.

Airplane weight is caused by the downward pull of gravity and varies due to several factors. These include weight of the basic airplane, equipment, passengers, cargo and fuel. The basic empty weight of an airplane always includes unusable fuel and optional equipment. Empty weight can be found in the aircraft records, changes to the equipment will also be noted in this document.

Airplane balance is controlled by the distribution of weight within the airplane. The center of gravity (which must be within designed limits) is the theoretical point where the weight is concentrated. You will have to relocate passengers, cargo or fuel (these last two are not always an option in small experimental aircraft) to move the CG to within limits.

Weight and balance limits (determined by the aircraft manufacturer) are placed on airplanes for two main reasons:

• Because of the effect of the weight on the airplane's primary structure and it's performance characteristics
• And the effect the location of this weight has on flight characteristics, particularly in stall and spin recovery and stability

Weight effects on aircraft
As far as weight is concerned, an aircraft with a weight problem will outperform in doing one thing: rate of descent. It is only useful when coming in for landing but not when climbing. A number of performance factors are influenced by a higher weight:

• higher takeoff speed
• longer takeoff ground run
• reduced rate of climb
• reduced angle of climb
• lower ceiling
• shorter range
• reduced cruise speed
• increased stall speed
• higher landing speed
• longer landing roll

Balance effects on aircraft
The distribution of weight in the aircraft determines if the center of gravity is within the limits set forth by the aircraft manufacturer. If it is not within the limits the aircraft is tail heavy or nose heavy.

• The tail heavy (unstable) situation is the worst. Stall recovery is more difficult and could be impossible. An unstable aircraft is also susceptible to over stressing as elevator forces become lighter.
• The nose heavy situation makes it harder to rotate on takeoff and flare for landing - assuming there is enough elevator control in the system. Of both situations the nose heavy one is the least worst.

Fuel effects on aircraft
Fuel can represent a large percentage of the weight, depending on the type of aircraft. Using fuel during flight therefore reduces the weight and possibly the balance depending of the location of the fuel tanks. This weight shift can result in a nose heavy or a tail heavy situation. The aircraft manual describes clearly where the tanks are located and if any effect is noticable or even serious on the W&B of the aircraft. Usually small two and four seat General Aviation aircraft with fuel tanks in the wings should experience only the loss off weight during flight.

As a result flight safety is greatly impaired when aircraft weight and balance calculations are not done properly.

So, now you know why you need to do the weight and balance calculations it is time to present a Weight and Balance form which can be used on most small aircraft.

Aircraft Weight & Balance form

This is the one we like to use. Click on the first row (item) for an explanation on how to use this.

To download a pdf version click here.

Important: Operating above the maximum weight limitation compromises the structural integrity of the airplane and adversely affects performance and safety.

Weight shifting

When the C of G is not within limits after calculating the Weight and Balance some redistributing of cargo or passengers need to be done. But how much and how far? You can shift a passenger in the W&B form and recalculate but there's an easier solution.

For this problem we have a basic formula: distance weight shifted x weight shifted = total weight x Change of C of G. Easy huh?

Thus, to recalculate the distance to shift a certain weight do this: distance weight shifted = (total weight x Change of C of G) / weight shifted.

Alternatively, if we knew the distance the weight must shift but want to know how much weight: weight shifted = (total weight x Change of C of G) / distance weight shifted.

Finally: remember to secure the cargo just in case unexpected turbulence is more than comfortable.