Division III - Flight Operations
- CARs Numbering System
- Guidance Material Numbering System
- Alternate Methods of Complying with the Regulation
- Division I
- Division II
- Division III
- Division V
- Division VII
- Division VIII
- Division IX
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RS743.37 Weight and Balance Control
The operator may meet the requirements of the regulations and standards through any means so long as these items are addressed:
The weight and balance calculation is accurate and complete;
Weight and balance tables when provided, must address the various possible passenger, fuel and cargo loadings;
Weight and balance tables when precalculated, must cater for various configurations;
Any process developed for weight and balance control must meet the standards and be preapproved; and
- For compliance with the CARs, CG "location" may refer to a range of safe values contained in the pre-calculated weight and balances tables. The range of values should cover the CG at maximum and minimum permissible fuel.
S743.37 Weight and Balance Control - Float Load Lines - Aeroplanes
Float load lines can be used as guidance information only. The air operator is still obligated to meet the regulations and standards for weight and balance calculation.
S743.37 Weight and Balance Control - Aeroplanes
Weight and balance can be manually or automatically derived. In either case it shall meet the requirements of Section 723.37 of the CASS.
The weight and balance control system shall be specified in the COM in accordance with Subsection 703.37(3) of the CARs. It may be published under separate cover, in which case it must be referred to and be considered as part of the COM.
Training is to be in accordance with Subsection 723.37(9) of the CASS.
When an air operator elects to implement an automatic weight and balance system, it should be carried out over a period as stated in the COM in a representative part of the operation. The previous method of weight and balance should be run as a shadow operation until the air operator is satisfied that the new system is safe and meets the requirements of Section 723.37 of the CASS
- Weight and balance computation may be incorporated in the operational flight plan or be a separate documentation.
2. Definitions and Abbreviations:
The following definitions are applicable in this guidance material:
Actual weight: when referenced to passenger weight, means the weight derived by actual weighing of each passenger just prior to boarding the flight, in the case of infants they shall be weighed along with the accompanying adult. Actual weighing of the passenger shall include allowances for personal clothing and carry-on baggage. The sum of the person’s weight, personal clothing and carry-on baggage is to be recorded as the weight of the passenger. Where weighing scales are not available or serviceable, or the passenger refuses to be weighed, the following weights may be used in lieu of actual weighing:
Volunteered Weight: Weight obtained by asking the passenger for their weight, adding 4.5 kg (10 lb) to the disclosed weight, then adding allowances for
personal clothing and carry-on baggage and using the resultant value as the passenger’s weight, or
Estimated Weight: Where actual weight is not available and volunteered weight is either not provided or is deemed to be understated, the operator may make a reasonable estimate of the passenger's weight, then add allowances for personal clothing and carry-on baggage and use the resultant value as the passenger’s weight.
Note: Personnel boarding passengers on the basis of volunteered or estimated weight should be able to, with a reasonable degree of accuracy, assess the validity of passenger’s volunteered weight, or estimate them, and shall include allowances for personal clothing and carry-on baggage. Where necessary, the volunteered weight should be appropriately increased so as to avoid gross inaccuracies.
- Volunteered Weight: Weight obtained by asking the passenger for their weight, adding 4.5 kg (10 lb) to the disclosed weight, then adding allowances for
Air Operator Segmented Weight: Approved segmented weights derived by the air operator from statistically meaningful data using a methodology that is acceptable to the Minister. These weights may be used in lieu of TCCA published segmented weights and are applicable only to that air operator and may be used only in the circumstances consistent with those under which the survey was conducted.
Basic Empty Weight: The basic weight of the aircraft as determined in accordance with the AFM.
Carry-On Baggage: The baggage that a passenger may carry onboard. Based on the particular aircraft stowage limitations, the operator may limit the number, size, shape and weight of the carry-on baggage so as to enable it to be stowed under the passenger seat or in the storage compartment. Otherwise, the standard allowance is 5.9 kg (13 lb) of carry-on baggage weight per passenger and remains constant throughout the year. The weight of the carry-on baggage shall be included in the weight of each passenger for the purpose of weight and balance calculations, unless otherwise notified.
Note: For those flights where the air operator does not permit any carry-on baggage, the weight of the carry-on baggage should be reduced from the passenger’s weight.
Empty Weight: In respect of an aircraft, means the total weight of the following parts or contents that are part of, or carried on board, the aircraft, namely;
- the airframe, including the rotor in the case of a helicopter or gyroplane;
- the power plant;
- the fixed ballast;
- the unusable fuel;
- the maximum amount of normal operating fluids, including oil, power plant coolant, hydraulic fluid, de-icing fluid and anti-icing fluid but not including potable water, lavatory pre-charge fluid or fluid intended for injection into the engines; and
- all of the installed equipment.
Female to Male Mix Ratio: The ratio of female to male passengers that are actually carried on board a flight, is expressed as a percentage ratio and is independent of the aircraft certificated seating capacity or configuration.
Large aeroplane: An aeroplane with an MCTOW of more than 5 700 kg (12,566 lb);
Maximum Certificated Take-off Weight (MCTOW): The weight identified as such in the type certificate of an aircraft.
Maximum Permissible Take-off Weight (MTOW): The maximum take- off weight for an aircraft as authorized by the state of registry of the aircraft or as provided for in the aircraft type certificate.
Operational Empty Weight: The actual weight of the aeroplane before loading for dispatch consisting of the aeroplane basic empty weight and may include removable equipment, flight crew members and crew members (including baggage), oil, unusable fuel and emergency equipment and shall be defined by the air operator;
Operations Personnel: Those personnel whose duties and responsibilities involve maintenance, loading, unloading, dispatching, servicing, weight and balance, passenger escort, flight crew, cabin crew, schedulers, de-icing crews, ramp people or anyone whose position involves them with the aircraft operation.
Passenger: A person, other than a crew member, who is carried onboard an aircraft, and for the purpose of weight and balance control is categorized as:
- Adult: A person who is aged 12 years and more;
- Child: A person who is aged between 2 years and less than 12 years;
- Infant: A person who is aged less than 2 years.
Personal Clothing or Clothing allowance: A standard weight allowance for personal clothing that a passenger may carry on board the aircraft. It is 3.6 kg (8 lb) for summer
and 6.4 kg (14 lb) for winter that must be added to the passenger’s weight for the purpose of weight and balance calculation.
Segmented Weight: The statistically derived average weight of an adult male or female passenger that has been modified by appropriate standard deviations to meet predetermined degree of accuracy and reliability, so as to be representative of the average weight of a small group of adult passengers. Segmented weights are intended to be used for weight and balance calculations and include allowances for personal clothing and carry-on baggage. Weight of infant is included in the segmented weight value, subject to the condition mentioned below.
Small aircraft: An aeroplane having a maximum permissible take-off weight of 5,700 kg (12,566 lb) or less, or a helicopter having a maximum permissible take-off weight of
2,730 kg (6,018 lb) or less;
Abbreviations used in this document:
AFM: Aircraft Flight Manual.
CARs: Canadian Aviation Regulations.
CASS: Commercial Air Service Standards.
CBAAC: Commercial and Business Aviation Advisory Circular.
FAA: Federal Aviation Administration.
FAA AC: Federal Aviation Administration Advisory Circular.
TC AIM: Transport Canada Aeronautical Information Manual
TCCA: Transport Canada Civil Aviation.
3. Duties and Responsibilities:
The air operator is responsible for establishing and implementing the weight and balance control system;
The weight and balance control system shall identify the following:
The flight operations management position having overall responsibility for the weight and balance control system;
The chain of command and the duties and responsibilities associated with each subordinate position;
The management position(s) responsible for ensuring that:
All necessary elements of the system have been properly developed, integrated, and coordinated;
All personnel who have been delegated duties and responsibilities have been trained and have acquired the required competency;
Sufficient competent personnel, adequate facilities and equipment that effect the system are available at each airport of planned operations; and
- Adequate management supervision of the system is maintained.
- All necessary elements of the system have been properly developed, integrated, and coordinated;
- The flight operations management position having overall responsibility for the weight and balance control system;
Responsibility during operations:
The air operator shall establish a chain of responsibility for the loading and establishment of the weight and balance of the aeroplane for every flight;
- Operations personnel, either employed by the air operator or authorized by the air operator, must be accountable and identifiable, whether by signature or computer input identification, for load data or services provided in accordance with their duties and responsibilities as detailed in system.
- The air operator shall establish a chain of responsibility for the loading and establishment of the weight and balance of the aeroplane for every flight;
4. Operational Requirements:
The weight and balance control system shall be detailed in the company operations manual and shall include:
How, before each flight, the air operator shall establish the accuracy of items listed in Subsections 723.37(1) to (7) of the CASS;
Preparation and disposition of all required documentation, whether completed by the air operator or other qualified personnel authorized by the air operator, are listed below;
- The procedure to establish the maximum allowable weights for the flight and to ensure that it does not exceed the AFM weight limits specified for various phases of the flight.
5. Computerized Systems:
Where load data are generated by a computerized weight and balance system, the operator must verify the integrity of the output data by a check to be performed at intervals not exceeding 6 months; and
- There must be a means in place to identify the person inputting the data for the preparation of every load manifest and the identity of that person must be authenticated and verified by the system and retained as required for paper copies.
6. On-Board Weight and Balance Systems:
- The advantage of this system over the traditional system of calculating the weight and balance is that this system calculates the actual weight and CG within its tolerance limits, eliminating the requirement for manual estimates and calculations. It can cater for last minute changes. An air operator must obtain approval to use an on-board weight and balance computer system as a primary source for dispatch. The on board system equipment has to be approved either through a TC or STC. The operator shall demonstrate the system reliability and accuracy for obtaining certification for its usage for flight dispatch. The procedure shall be detailed in the COM. Guidance contained in FAA AC 20-161 (latest version) may be used, as applicable to the Canadian context.
7. Computation of Passenger and Baggage Weights:
Air operator is to ensure that due diligence is exercised by personnel compiling the weight and balance report to ascertain that the passenger and baggage weight calculation accurately reflects the aircraft load that will be carried on every flight. Either of the two methods mentioned below may be utilized to calculate passenger and baggage weights, but the air operator must specify in the COM the conditions where either of them is to be selected:
Actual Weights: By way of the actual weight of each passenger, including allowances for personal clothing and carry-on baggage; and the actual weight of checked baggage; or
- Segmented Weights: By way of segmented weight, which include allowance for personal clothing and carry-on baggage; and the actual weight of checked baggage;
- Actual Weights: By way of the actual weight of each passenger, including allowances for personal clothing and carry-on baggage; and the actual weight of checked baggage; or
1. Actual Weights:
In determining the actual weight by weighing, an air operator must ensure that passenger clothing and carry-on baggage are weighed and their weights included in the weight of the passenger. Weighing shall be conducted at a location immediately prior to boarding to avoid the chances of the passenger acquiring additional load just before boarding the plane.
Where a passenger refuses to being weighed, the air operator should make use of volunteered weight, and if that is not provided estimate the passenger’s weight.
Allowances for personal clothing and carry-on baggage shall be included in the weight of each passenger, except where the air operator does not permit any carry-on baggage on the flight the weigh of carry-on baggage shall be reduced from each passenger’s weight.
- Personnel boarding passengers on the basis of volunteered weights or estimated weights should be be able to assess with a reasonable degree accuracy the validity of the disclosed weight or estimate them, and should take great care to avoid gross inaccuracies.
- Where a passenger refuses to being weighed, the air operator should make use of volunteered weight, and if that is not provided estimate the passenger’s weight.
2. Segmented weights:
The predetermined level of confidence range and error tolerance incorporated in the segmented weights ensure that the total weight of the adult passengers will not exceed the aggregate obtained by using segmented weight and the latter will not exceed the actual weight by more than 1% in 95% of the cases.
Segmented Weight Tables were developed by TCCA for use by subpart 703 operators as an alternative to actual weights for weight and balance calculations. Separate tables were developed for summer and winter to account for seasonal differences.
A statistical methodology was used to arrive at the values published in the Segmented Weight Tables. Firstly, TCCA updated the average weight of Canadian males and females aged 12 and over, on the basis of a study titled the Canadian Community Health Survey Cycle 2.1, 2003, which obtained large-scale weight data by surveying some 130,000 Canadians through interviews. Thereafter, standard deviations were derived as 16.8 kg (37 lb) for males and 14.6 kg (32.2 lb) for females. These were used to check conformity with the predetermined degree of accuracy and reliability. The average weights were further modified to cater for specified certificated seating capacity ranges so as to be representative of the highest average weight amongst all sample sizes for that range. Finally, a constant value of 5.9 kg (13 lb) for carry-on baggage and 3.6 kg (8 lb) for summer clothing or 6.4 kg (14 lb) for winter clothing were added, and the resultant values were recorded as segmented weights. Segmented Weight Tables are reproduced below; and will be published in the the next issue of TC AIM RAC 3.5 – Weight and Balance Control.
Where no carry-on baggage is permitted the weight of carry-on baggage shall be reduced from each passenger’s weight.
- Segmented weights are to be used in the same method as the standard weights that were hitherto used.
8. Applicability of Segmented Weights:
On any flight identified as carrying a significant number of passenger whose weight or carry-on baggage are deemed to be in excess of the segmented weights (TC published or air operator derived), actual weights should be used.
Actual passenger weights should be used for aircraft certificated for 4 or less passenger seats. Segmented weights are applicable for aircraft certificated for 9 or more passenger seats that are reconfigured for no more than 9 passenger seats so as to enable them to operate under subpart 703.
- Subpart 703 air operators are restricted from using standard weights, instead are recommended to use either the actual weights or segmented weights (TC published or air operator derived) for their weight and balance calculations.
9. Weight of Children and Infants:
In the case of infants, they shall be weighed-in together with their accompanying adult. Where segmented weights are used and the number of infants exceed 10% of the number of adult passengers, the weight of each infant shall be included separately using the standard weight for infants. Where infants occupy separate seats, they shall be treated as children for the purpose of weight and balance calculation and their weight included using the standard weight for children. Each child shall be weighed-in or their weight included using standard weight for children.
10. Checked baggage and cargo:
The air operator must use the actual weight of Checked Baggage and Cargo.
11. Establishment of Air Operator Segmented Weights:
Appendix A provides an acceptable means, but not the only means, to conduct an air operator weight survey. This document is not mandatory and does not carry any regulatory obligations. However, air operator intending to use it should comply with it in its entirety.
12. Training Program:
Training on the weight and balance control system must be provided in accordance with Subsection 723.37(9) of the CASS and be part of the air operator training program.
13. Weight and Balance Document Retention
The storage of the weight and balance documentation including all amendments may follow the same procedure as for operational flight plan specified in Section 703.18; and shall be detailed in the COM.
The air operator shall specify in the COM how the weight and balance data and documentation would be retrieved or recreated for Transport Canada for the purposes of audit, inspection, investigation and flight safety.
The air operator is required to retain copies of the weight and balance documentation where it is not incorporated in the operational flight plan. This data may be stored electronically if the following criteria are met:
It shall meet the retention period specified for paper copies;
The air operator must show that they have a system for safe storage, or archiving of electronic data;
A hard copy must be retained for documents that require verification by signature unless the air operator has a system of electronic signature verification and document authentication;
The air operator should have a documented plan detailing procedures for the recovery of all electronically stored data. The company shall maintain a list of the stored information pertinent to the weight and balance record and examples of the forms and content of the data that can be recovered; and
- Stored date must be presented in a form that is acceptable to TC within 48 hours from the time of a request.
- It shall meet the retention period specified for paper copies;
14. Frequently Asked Questions
Appendix B contains responses to frequently asked questions (FAQ)
|Maximum Certificated Passenger Seating Capacity||WINTER||SUMMER|
|1 – 4||Use actual weights; volunteered weights + 10 lbs; or estimated weights.|
|6 – 8||198||237||192||231|
|9 – 11||191||229||185||223|
|12 – 16||188||226||182||220|
|17 – 25||185||222||179||216|
|Children||Listed for convenience. Each child is included as 34 kg (75 lb), which includes personnel clothing and carry-on baggage.|
|Infants||Listed for convenience. Weight of infants to be included only where the number of infants exceeds 10% of the adult passengers. Each infant will be included as 13.6 kg (30 lb), and this includes clothing and the accompanying carry-on baggage. Where an infant occupies a separate seat, the infant shall be treated as a child and included as 34 kg (75 lb).|
ACCEPTABLE MEANS OF COMPLIANCE
WEIGHT SURVEY CONDUCTED BY AIR OPERATOR
Air operators have the option of using segmented weight values other than those published by TCCA. Those who intend to do so must make their intentions and reasons known to TCCA and obtain approval before conducting the weight survey. Details of the survey plan are to be included as they also require preapproval. The results will have to verified and approved by TCCA before implementation. The surveyed weight values shall be used by the air operator and only under the circumstances consistent with those under which the survey was conducted. The surveyed weight values shall be reviewed every 5 years.
On any flight identified as carrying a significant number of passengers whose weights are estimated to be in excess of the surveyed weight values, or the number of carry-on baggage or weight of the carry-on baggage is predicted to be in excess of the predetermined value, actual weighing shall be used.
Air operators are required to conduct large scale surveys comparable to those conducted by TCCA, in order to derive gender wise average adult passenger weights. Thereafter, according to the seating capacity of the aircraft, these average weights will have to be modified by applying standard deviations as per the gender and the resultant value used as segmented weights.
The segmented weights are required to guarantee a confidence range of 95% with error tolerance of 1%. Confidence range of 95% is commensurate with other civil aviation regulators. However, TCCA has adopted the error tolerance of 1% for all calculation of segmented weight, which is more stringent than other regulators who have maintained a 1% error tolerance for calculating segmented weight for combined passenger loads and a 2% error tolerance for calculating genderwise segmented weights.
The air operator may consult with an accredited professional entity for conducting the weight survey. It is the responsibility of the air operator to demonstrate to TCCA that their consulting entity has the expertise to conduct large scale surveys and statistical analysis, similar to the methodology used by TCCA.
The survey must be fully representative of the operation, i.e. the network or routes, seasons, locations, passengers should be typical, and survey should sustain the operations for which the surveyed weights are intended to be used. The detailed plan must be specific in terms of weighing locations, dates, flight numbers and number of passengers/bags to be weighed in the survey. The actual survey must then be conducted in accordance with the plan and any deviations should be justified and the potential impact of the deviations on the survey results addressed.
The weight survey shall be conducted by the air operator for a period of not less than 60 consecutive days and the survey will have to be monitored by TCCA.
- Since seperate segmented weights are required for adult male and female passengers, the procedure detailed below is required to be repeated for adult male and female passengers.
Procedure For Establishing Revised Standard Weight Values For Passengers And Baggage
This section provides an acceptable survey method for determining segmented weights for weight and balance control. Surveys conducted correctly allow an air operator to draw reliable inferences about large populations based on relatively small sample sizes. In designing a survey, an air operator should consider—
The sample size required to achieve the desired reliability;
The sample selection process, and
- The type of survey (average weights or a count of items).
1. Sample Size
Sample size depends on the population. The more varied the population, the larger will be the sample size to obtain a reliable estimate. Too small a sample size will yield grossly inaccurate results; too large a sample size will waste scarce resources and will not provide a more accurate result, because the relationship between sample size and statistical accuracy is not linear. Therefore, it is important to achieve the correct balance.
For calculating the required sample size it is necessary to make an estimate of the standard deviation based on standard deviation derived from surveys for similar population and having the same significance and error tolerance. If standard deviation from previous survey is not available, a small representative sample of about 100 passengers has to be weighed so that the required values can be calculated. An example of such a method is provided below.
The formula to derive the absolute minimum sample size must achieve a 95-percent confidence level with 1% error tolerance. Those who do not wish to use the formula may use the minimum sample size of 2700 to obtain the predetermined level of confidence and tolerance. [Table 2-4 Minimum Sample Size, Paragraph 210, FAA AC 120-27E]
- If the analysis of the survey results indicate that the derived weight values of the adult male or female passengers do not meet the requirements of confidence and accuracy, an additional number of representative passengers shall be weighed in order to satisfy the statistical requirements.
2. Weight Sampling Method:
It is recommended that air operators employ random sampling techniques. Random sampling means that every member of a group has an equal chance of being selected. If an air operator conducts a survey that does not employ random sampling, the selected sample may not represent the larger group as a whole and the conclusions drawn from such a survey may not be valid.
The following are two of the examples of random sampling methods, (An air operator may also consult a basic textbook on statistics to determine if another random sampling method is more appropriate):
Simple random selection. An air operator should assign a sequential number to each member in the group (such as passengers waiting on a line). Then the air operator randomly selects numbers, includes the sample number and records the corresponding data. The air operator repeats this process until it has obtained the minimum sample size.
Systematic random selection. An air operator should randomly select a
sequence number and a number to begin the process of obtaining samples. The air operator should then use the predetermined sequence to select and complete the sampling. For example, an air operator selects every fifth person in line to participate in the survey (sequence of 5) and starts with sample number 3 (starting number). The air operator then selects every fifth person after that to participate in the survey (sample number 3, 8, 13, 18 etc). The air operator continues to do so until the minimum sample size has been surveyed.
- Simple random selection. An air operator should assign a sequential number to each member in the group (such as passengers waiting on a line). Then the air operator randomly selects numbers, includes the sample number and records the corresponding data. The air operator repeats this process until it has obtained the minimum sample size.
An air operator also has the option of surveying each passenger.
It must be remembered to include personal clothing and carry-on baggage in the survey.
A passenger has the right to decline to participate in the weight survey. If a passenger declines to participate, the air operator should select the next passenger based on the air operator’s random selection method rather than select the next passenger in a line. If a passenger declines to participate, an air operator should not attempt to estimate data for inclusion in the survey.
- The selection of random samples must, by nature and extent, be representative of the passenger volume, considering the type of operation, the frequency of flights on the routes, in/outbound flights, applicable season and the passenger seating capacity of the aeroplane.
3. Developing a Survey Plan
Before conducting a survey, an air operator should develop a survey plan. The plan should describe the dates, times, and locations the survey will take place. In developing a survey plan, the air operator should consider its type of operation, hours of operation, markets served, and frequency of flights on particular routes. An air operator should avoid conducting surveys on holidays because it will not be representative of everyday operation, unless the air operator has a reason to include those days.
- TCCA would require overseeing the survey process and validate the execution of the survey plan. Once the survey is started it shall continue until it is completed, even if the initial survey data indicates the average weight is lighter or heavier than TCCA published weights. Once the survey results are verified and approved by TCCA it becomes binding on the air operator.
4. Collecting Data For Passenger Weights:
Weighing Passengers. An air operator that chooses to weigh passengers as part of a survey should take care to protect the privacy of passengers. The scale readout should remain hidden from public view. An air operator should ensure that any passenger weight data collected remains confidential.
Children: No gender wise differentiation is required to be made for weighing children. Their weight shall include the weight of their personal clothing and carry-on baggage. In the Canadian context, segmented weights are not applicable to children, therefore, they are not required to participate in the survey.
Infants: Infants shall be weighed together with the accompanying adult.
The weight of each passenger sample shall be recorded gender wise, with flight number, date and shall include personal clothing. After recording the data of the entire sample a statistical anaysis is required to be carried out as mentioned in this document to determine the segmented weight of the adult male and female passenger.
- Rounding off: In statistics rounding off should not be done until the final calculation is reached. If the weights are displayed digitally, record the displayed value. If the display is a dial read out, and the pointer rests between two graduations, where it is less than half way between the two graduations take the nearest reading and where it is half way or more take the next higher reading. When determining the final values after completing the calculations, round off to the whole kg or pound, as appropriate.
5. Weighing Location:
An air operator should accomplish a survey at one or more airports that represent at least 15 percent of an air operator’s departures. These locations should include those airports that serve connecting passengers so that they have an equal chance of being selected in the survey. These locations should provide a sample that is random and representative of its operations.
- The location for the weighing of passengers shall be selected as close as to the boarding point as possible, where a change in the passenger weight by disposing of or by acquiring more personal belongings is unlikely to occur before the passengers board the aeroplane.
6. Weighing Machines
The weighing machines should have the capacity to weigh at least 150 kg (330 lb), with graduations of 500 g or 1 lb, and an accuracy of 0.5 %. It should be caliberated before conducting the weight survey.
7. Survey For Particular Routes
An air operator may conduct a survey for a particular route if the air operator believes that the average weights on that route may differ from those in the rest of its operations. To establish a standard average passenger weight along the route, an air operator may survey passengers at only one location. However, where there is a transfer, an air operator should conduct surveys at the departure and arrival locations, unless the air operator can verify there is no significant difference in the weights in either direction along the route.
A Hypothetical Worked Example of Adult Passenger Weight Survey
In this example it is presumed that the air operator has not conducted a previous passenger weight survey hence does not have “a priori” average passenger weight and standard deviation. In the absence of this data, a small sample group (about a 100), chosen from random sampling, are required to be weighed to collect the required data. Since data is required to be collected gender wise, only the workings for male passengers are shown. In this example the sample group consists of 86 randomly chosen adult male passengers.
Note: “a priori” in statistics means estimates or data from a different or previous equation
|Number of Passengers = n||Weight of Individual = xj (lb)|
14,706 = 171
In plain language – the average weight = (the sum of all the individual weights) divided by (the number of individuals).
|Passenger Number||Individual Weight||Difference From Mean||Square of the Difference|
|n||xj (lb)||xj – x (lb)||(xj – x)2 (lb)|
|σ’ =||σ’ = standard deviation|
|σ’ =||σ’ = 40.02 lb|
In plain language:
Subtract the mean from each person’s weight and record it (+/-
values)(Difference from Mean column)
Square the differences for each person (Square of the differences column)
Add all the square of the differences
Divide the sum of all the differences by the number of persons less 1(in this case 86-1=85)
- Square root the result and this gives the standard deviation.
Step 3 – Determining the Sample Size for the Passenger Weight Survey
Having obtained the average weight and the standard deviation, the next step is to determine the sample size which is also related to the error tolerance, in this case it is determined to be 1%.
Formula for determining sample size is
n = size of the sample to be weighed (males and females separately)
σ’ = standard deviation
èr = error tolerance = 1% = 1
μ' = average weight of sample group
1.96 = value of Gaussian distribution for 95% confidence level
Using the values obtained from our pilot sample project:
n ≥ ( 1.96 * 40.02 * 100) 2 = 2104.137 = 2104 samples
(1 * 171)2
Note: These are fictitious figures, introduced only to illustrate the steps.
Step 4 – Conduct the Weight Survey as per the Survey Plan
The above calculation indicates that 2104 adult male passengers and 2104 adult female passengers are required as the minimum sample size to conduct the survey.
Step 5 – Determining the Average Adult Male and Female Weights.
For this example we are weighing 2104 adult male passengers and the sum of all their weights
n = 2104
= 368,453 lb (sum of all the individual weights)
= 175.120 lb (average adult male passenger weight)
Step 6 – Calculating the Standard Deviation
= 2,115,569 (sum of all the (differences from average weight)2 )
standard deviation =
= 31.71 lb
Step 7 – Calculating the Accuracy of the Sample Average
= 1.96 * 31.71 * 100
√ 2104 * 175.120
er = (error tolerance) = 0.774 % - which is within the predetermined level of 1%
Step 8 – Checking the Confidence Range
= +/- 1.355 lb (rounding off +/- 2 lb)
The result indicates that there is 95% probability that actual mean of all passengers being within the range of 173 and 177 lb (175 +/- 2 lb). Since rounding down is not recommended the average weight of the adult male passenger should be taken as 177 lb.
Step 9 – Adjustment of Average Weight as per Certificated Seating Capacity of the Aeroplane
For determining the average weights in relation to the certificated seating capacity of the aircraft use the following table:
|Certificated Passenger Seating Capacity||
To The Average Weight
Summer and Winter
|6 – 8||31||27|
|9 – 11||23||20|
|12 – 16||20||17|
|17 – 25||16||14|
Step 10 – Results of the Weight Survey
The results of the weight survey should be summarized and deviation from the published segmented weight should be justified. The air operator derived weights should include weights for personal clothing and carry-on baggage. Weights should be adjusted to cater for the certificated seating capacity of the aircraft. The weights should be rounded off to the nearest whole number.
Step 11 - Suggested headings for the weight survey:
– Objective and brief description of the weighing survey
2 Weighing survey plan
– Discussion of the selected flight number, airports, dates, etc.
– Determination of the minimum number of passengers to be weighed.
– Survey plan – how the weight survey will be conducted.
3 Analysis and discussion of weighing survey results
– Significant deviations from survey plan (if any) and justification.
– Variations in the mean and standard deviations in the operator’s network.
– Discussion of the results.
4 Summary of results and conclusions
– Main results and conclusions.
– Proposed deviations from published standard mass values.
Applicable weight values for summer and/or winter timetables or flight programmes.
Weighing results per flight (showing individual passenger masses and sex); means and standard deviations per flight, per route, per area and for the total network.
FREQUENTLY ASKED QUESTIONS ABOUT
WEIGHTS AND WEIGHT AND BALANCE CONTROL FOR
SUBPART 703 – AIR TAXI OPERATIONS
1. Is this Advisory Circular (AC) enforceable?
This AC provides guidance, explanations, recommendations and best practices, but it does not carry any regulatory weightage, hence is not enforceable.
2. Is the use of segmented weight mandatory?
Use of segmented weight is not mandatory. It is one of the acceptable options for weight and balance control for subpart 703 air operators, who have other options to demonstrate compliance with the applicable regulations and the standards. Subpart 703 air operators are restricted from using standard passenger weights.
3. What is the purpose of the air operator’s weight and balance control?
The Regulations require that the aircraft shall never be outside the weight and centre of gravity limitations as specified in the AFM or the Pilot Operating Handbook (POH). There is no escape from this obligation. The air operator’s weight and balance control should be focused on meeting this commitment. It does not matter what means are used for computing the weight and balance of the aeroplane, as long as it ensures that the aircraft conforms to its weight and balance limitations at all times.
4. Who is responsible for exercising the weight and balance control?
The air operator is responsible for establishing, implementing and ensuring the accuracy of its weight and balance control; obtaining approval from TCCA prior to its implementation; detailing the procedure in the COM and to train its personnel to acquire the required competencies. The PIC, being the final authority for the flight, is ultimately responsible for ensuring that the aircraft’s weight and balance is never in excess of its limitations. The PIC has no relief from this responsibility.
5. Why is there an increased restriction in the weight and balance control for subpart 703 air operators?
More than a thousand flights operate daily under subpart 703. Most of these flights operate at their weight limitations and use standard weights for their weight and balance calculations. TSB determined that for small passenger seating capacity aircraft, use of standard passenger weights underestimate the actual weight of the passengers, resulting in the aircraft being overweight when actually loaded. Therefore, the sheer number that flights that operate at their maximum gross weights and the prospect that because of the use of standard weights, though these flights in the weight and balance document appear to be operating within their weight and balance envelope could in reality be operating outside of it, expose these aircraft and the industry to a high degree of risk. Increased restriction in weight calculations for subpart 703 air operators was introduced to mitigate this risk.
6. What recommendations were issued by TSB to mitigate the risk of overweight condition of the aeroplanes?
TSB determined that aircraft overweight were contributable factors in some of the accidents and issued the following two recommendations:
Recommendation A04-02: To revise the standard weights so as to make it more realistic with the current population. TCCA accomplished this by revising the standard weights in 2005.
- Recommendation A04-01: To make the use of actual weights mandatory for aeroplanes configured for 9 or less passenger seats.
Note: In this document, “passenger seats” do not include “pilot seats”.
7. Were these recommendations implemented?
Recommendation A04-02 was implemented. Regarding Recommendation A04-01, TCCA perceived that this recommendation would impact the entire subpart 703 air operators. This issue was discussed in the Canadian Aviation Regulation Advisory Council (CARAC) and the following consensus was reached:
Modifying this recommendation to provide greater relief to subpart 703 air operators by:
Mandating the use of actual weights only for aeroplanes having a seating configuration, excluding pilots seats, of 4 or less, and
Making the use of actual weights as an optional means of compliance for aeroplanes with seating capacities of 5 or more, that are operated under subpart 703;
- Mandating the use of actual weights only for aeroplanes having a seating configuration, excluding pilots seats, of 4 or less, and
Restricting the use of standard weights for all subpart 703 air operators so as to mitigate the risk of exceeding the aeroplane weight limitations;
Continue the use of volunteered weight as in lieu for actual weight;
When neither the actual weight nor the volunteered weight is available, the option to use estimated weight as in lieu for actual weight;
- Introducing segmented weight as an acceptable means of compliance for computing the weight and balance of aeroplanes having a seating capacity of 5 or more and operating under subpart 703.
8. What invoked the introduction of segmented weights?
Notice of Proposed Amendment (NPA) 2008-58 perforce amended Standards 723.37(3) to read:
Note: The new text does not contain “standard weights” and made the use of “actual weights” or “segmented weights” as an acceptable means of compliance.
9. Passenger weighing and options when this is not possible?
Weighing of passengers is voluntary and it should be done confidentially. The read out should not be visible to the public. The data collected should be used only for the purpose for which it was collected. If the data is required to be stored, it should be in safe custody. Passengers may refuse to be weighed or there could be instances where the weighing is not practical or the weighing machines are not available. During the CARAC process, it was decided that under such circumstances, the following weights may be used 'in lieu' of actual weights:
Volunteered weight; and
- Estimated weight.
Note: Only the above two options are available as alternatives for actual weight.
10. Volunteered Weights and Estimated Weights are susceptible to inaccuracies; how are these avoided?
When people volunteer their weight it is generally bare body weight, so weights for personal clothing and carry-on baggage shall be included. They could also understate their weight. Therefore, personnel boarding the flight should add 10 lb (4.5 kg) to the disclosed weight. Also, personnel who are responsible for boarding passengers should be able to discern when weights are underestimated and as well be able to estimate passengers’ weights with a reasonable degree of accuracy. Where air operators opt to use volunteered or estimated weights, it may be necessary to train their personnel to acquire the skill to predict the weights competently.
11. Can this training be elaborated?
It is emphasized that, currently, to obtain an accurate weight of each passenger, is to actually weigh them before boarding the flight; all the other methods are estimates or statistical derivation that aims to be as close to reality as possible.
It is necessary that personnel boarding the passenger are trained so as to judge passenger’s weight consistently with a reasonable degree of accuracy. Some means of imparting this training is listed below, but the air operator can adopt any means that provides acquisition of the required competency. The details of the training should be listed in the COM. TCCA has not prescribed any specific training.
Suggestion 1: One of the means, but not the only means, is to train the personnel to estimate the weight of volunteers. Volunteers should comprise males and females of different weight and height; attired in appropriate summer or winter clothing; and weight estimation should be checked for consistency and accuracy. The exercise may require to be repeated till the desired level of competency is achieved.
Suggestion 2: Large scale pictures or silhouettes of males and females, in summer and winter clothing, may be displayed near the boarding point for easy assessment of the passenger’s weight. The weight estimation should be checked for accuracy. This exercise should be repeated till the desired level of competency is reached.
Suggestion 3: Comparison with self. With self as the yardstick, judge the passenger’s weight – leaner will mean lesser weight and stouter will mean heavier weight; by how much – is left to judgement which can be gauged by training and checking.
The estimated weight can be confidentially discussed with the volunteers, or checked against actual weighing that is being conducted in parallel.
The aim of the training is to ensure that the actual weight shall not exceed the estimated weight.
- The air operator may need to revise the COM to realign the weight and balance control system and the training requirements to reflect these procedures.
The bench mark used for segmented weight (95% confidence level with 1% error tolerance and ensuring actual weight never exceeds estimated weight) may set as the required competency level for this training.
12. Are air operators obliged to use volunteered or estimated weights? What other options do they have?
Air operators are not obliged to use either of these weights. They could use actual weighing or segmented weights. They could also use any other means that can demonstrate compliance with the regulations and standards, provided it has been approved by TCCA for its implementation. No matter what means are used, there is no dispensation from meeting the requirements of the regulations and the standards.
13. Can standard weights be used by Subpart 703 air operators?
Due to the implementation of the current subsection 723.37(3) of the CARs, air operators under subpart 703 are restricted from using standard weights.
14. What recourse does the air operator have if the segmented weight imposes an unacceptable weight penalty?
By design, segmented weights are higher than standard weights. If the air operator deems that the use of segmented weight imposes an unacceptable weight penalty, then they should use actual weight, volunteered weight, or estimated weight. If volunteered weight and estimated weight are not acceptable, because the air operator does not have trained personnel, then there is no other choice but to use actual weighing.
15. Aircraft with a certificated seating capacity of more than 9 passenger seats have segmented weight values that are 17 to 20 lb heavier than standard weight. How is TCCA ensuring a level playing field between subparts 703 and 704 air operators using these larger capacity aircraft?
By design segmented weights are heavier than standard weights, because the average weight has been increased by the inclusion of standard deviation so as to ensure that the weight value reflects the highest average within the grouping of aircraft certificated seating capacity. In comparison, subpart 704 air operator who is operating the same capacity aircraft, has the allowance of using standard weight.
Subpart 703 air operators of these aircraft types, who deem that the weight penalty is unfair, should either use actual, volunteered or estimated weight; or should opt to operate under subpart 704 of the CARs. Currently, amendments to the standards 723.37(3) are not under consideration.
16. Can an air operator derive their own segmented weights?
Air operators have the option to use weights other than those published by TCCA. The intent to conduct a weight survey and the methodology to be used for the survey must first be approved by the Minister before the survey is actually conducted. Details are provided in Appendix A above.
17. Why should air operator’s weight survey be comparable to the TCCA process for acceptance and approval by the Minister?
TCCA is aware that most air operators lack the resources to conduct a weight survey. They would outsource this project to third parties; who in order to win the contract may resort to shortcuts or abridge the process to undercut cost and time. The outcome of such a survey would be significantly inaccurate and unacceptable; and a waste of resources.
This survey is critical and demands accuracy and meticulous execution. Deviations, shortcuts and sidesteps will yield inaccurate results. To safeguard against these pitfalls TCCA has determined that the survey program has to be approved by the Minister prior to its conduct. Appendix A cited above provides an acceptable means of conducting the weight survey.
18. Why aircrafts with certificated passenger seating capacity of 4 or less are mandated to use actual weights?
Though the standards permit subpart 703 air operators to use segmented weights, it was determined that statistically segmented weight values cannot achieve the predetermined level of confidence and accuracy without incurring unacceptable weight penalty. It was further analysed that the only method to mitigate the risk of aircraft being loaded overweight is to use actual weights. Hence, this category of aircraft has been restricted to use only actual weights.
19. What options does an air operator have for weight and balance control of aircraft having a certificated seating capacity, excluding pilot’s seats, of 5 or more?
Air operators using aeroplanes of above mentioned seating capacity can avail of the following options:
Actual weighing of each passenger;
Estimated weight; or
- Segmented weight.
If the air operator elects not to use segmented weight because of unacceptable weight penalty, and is not confident to use volunteered or estimated weight due to lack of trained personnel who can provide the required level of accuracy, then the air operator is left with no other option but to use the actual weighing.
20. What procedure is required to be followed if the passengers are outside the predicted segmented weights listed in the tables?
Like when using standard weights, where a significant number of passengers are deemed to be outside the segmented weight values, actual weight should be recorded. If actual weighing of each passenger is not possible or practical, then the air operator may make use of volunteered weight or estimated weight by ensuring these are diligently used.
21. What standards are required to be met for using weighing machines?
TCCA has not recommended any weighing scales or weighing machines nor do they provide any certification or standard for this equipment. It is recommended that the weighing machines should have the capacity to weigh 150 kg (330 lb), graduation at least of 500 g or 1 lb, and an accuracy of 0.5%. The company is at liberty to use any equipment they deem fit. No matter which type of weighing machine or weighing scale is being used, the weight and balance computation shall ensure that when the aircraft is actually loaded it is within its weight and balance limitations. The onus of selecting the equipment, ensuring its availability, accuracy, serviceability, and imparting the necessary training rests solely with the air operator. Even the commonly used domestic weighing scales may be utilized by air operators, provided they ensure that these scales are properly maintained, regularly calibrated, and their accuracy checked routinely. The observed weight, its correction and the final value should be recorded.
22. Checked baggage is required to be weighed. Can the same weighing machine be used for weighing passengers?
There is no objection in using the same machine for weighing passengers, provided the passengers do not object to this procedure, the read out is confidential and hidden from public view, and the data collected meets the requirement of record keeping specified in the AC 703-004 and this Guidance Material.
23. For the same flight can some passengers be subjected to one type of weight system and the rest be subjected a different type of weight system?
On any flight it is not acceptable to use a combination of actual weight and segmented weight. Actual weight includes volunteered weight and estimated weight. Therefore, on any flight use either the actual weight or the segmented weight.
24. When using segmented weight tables is it necessary to determine male / female mix ratio to compute the passenger load.
The segmented weight tables have been simplified. They do not contain male/female mix ratio. The tables are used in the same fashion as the standard weights, except that for segmented weights the certificated passenger seating capacity has to be taken into account.
25. Subpart 703 air operators are permitted to carry no more than 9 passengers, yet the table has listings for certificated seating capacity up to 25 passengers.
By virtue of certain exemptions, specific aircraft types, for example DeHavilland DHC3T – Turbo Otter, are permitted to be operated under subpart 703; and certain larger capacity aircraft under Supplemental Type Certificate or (Limited) Supplemental Type Certificate are authorized to operate under this subpart, by reconfiguring them to carrying no more than 9 passengers. So, the segmented tables were expanded to include aircraft with a seating capacity up to 25 passenger seats. It was determined that larger capacity aircraft would not be able to operate under this subpart.
RS743.39 Briefing of Passengers - Standard Safety Briefing
The intent of this regulation and standard is to ensure that all of the required areas of concern are briefed. The air operator has some discretion on how this is accomplished and when it is accomplished. The circumstances of the operation will determine what procedures work the best.
The briefing prior to take-off can be completed before boarding the aircraft, after the passengers are boarded or any time during taxi that is convenient.
The briefing prior to passenger disembarkment can be completed any time after landing. It is recommended that the briefing be done immediately before allowing the passengers to deplane.
For the purpose of the briefing in the event of an emergency, the phrase "when time and conditions permit" allows the pilot the discretion to utilize his/her time and resources in the best way that the pilot sees fit.
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