n ≥
.
..
1.96*σ '*100
er '*μ'
.
2
..
where:
n is the number of passengers to be weighed (sample size)
er ' is the allowed relative confidence range (accuracy) for the estimate of μ by (see also
equation in paragraph 3).
NOTE: The allowed relative confidence range specifies the accuracy to be achieved when estimating the true mean. For example, if it is proposed to estimate the true mean to within ± 1%, then er ' will be 1 in the above formula.
1.96 is the value from the Gaussian distribution for 95% significance level of the resulting confidence interval.
A. LOADING GENERALITIES
. Calculation of average mass and standard deviation.
n
∑
x
j
j=1
Arithmetic mean of sample: μ=
n Where xj are the mass values of individual passengers (sampling units).
2
n
...
...
∑
x . x _
j
Standard deviation: σ=
n .1
3.2.2. Accuracy of the sample mean.
The accuracy (confidence range) which can be ascribed to the sample mean as an indicator of the true mean is a function of the standard deviation of the sample which has to be checked after the sample has been evaluated. This is done using the formula:
1.96*σ *100
=
whereby er should not exceed 1%. The result of this calculation gives the relative accuracy of the estimate of μ at the 95% significance level. This means that with 95% probability, the true average mass μ lies within the interval:
1.96 *σ
LOADING LOADING
A. LOADING GENERALITIES
4. LOADING OPERATIONS
4.1. Preparation before loading
4.1.1. Generalities
Air transport is not more risky than other ways of transport. Indeed, air journey, with no vibration, shunting or bumping shocks, is probably the smoothest method of carrying cargo. Air transport has another advantage that can be very useful for cargo such as perishable goods or live animals: its rapidity.
To ensure an adequate loading and a safe air transport, it is necessary to prepare the shipment. The shipment must be checked and pre-packed before loading.
4.1.2. ULD / Bulk
Airbus aircraft have different configurations of compartments: they can be loaded either with bulk or with ULDs (Unit Load Devices). The different configurations for each aircraft are described in the —Cargo systems“ part of this manual.
In bulk compartments, all the items are stacked without any order. Compartments equipped with the Cargo Loading System are filled with ULDs. These ULDs allow to group items into larger units, which is easier and faster to load.
ULDs can be either pallets or containers. Certified containers protect the aircraft systems and structure. They are expensive and delicate units because of the materials used to make it. Non certified containers are sometimes used to take several loads into large pre-packaged units. Both pallets and containers are locked in the aircraft using latches and end-stops.
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