The specs of the cargo levels would need to be locked.
The current plan is to include three levels of cargo which determine the size of aircraft they can be loaded into. Each cargo level will have a different volume vs weight ratio and a different "price" (other specs could be added too but I don't feel it's necessary). Since cargo is a very variable thing that comes in all shapes and sizes the idea is to dumb it down a bit and use three standard types of cargo which have always the same specs - think of them as the average representations of the main types of cargo.
|Type||Allowed aircraft sizes||Weight (kg) per Unit (m3)|
|Light cargo, Mail and small parcels (bulk) ||All pax and cargo planes ||?|
|Standard cargo, Misc. cargo ULDs ||All cargo planes (apart size class Small), and pax planes of size Large & Very Large ||?|
|Heavy cargo, Large and/or heavy cargo ||Only cargo planes of size Large & Very Large ||?|
This is a simplified solution still providing flexibility for different operations and benefits for using real cargo planes.
The downside is that it's again limited to the 4 aircraft size classes, and will not take into account for example the fact that a pax-only B727 couldn't really handle that much cargo since the freight doors are so small and it cannot accept containers - while a A320 in the same size class can in real life take larger cargo units. But adjusting the accepted cargo types on individual aircraft model basis is too much work already in my mind.
Cargo demand would be presented in volume, cubic meter / feet, (since the players are able to see the available cargo volume in their aircraft) for each route pair. And the weight of the cargo per volume is calculated using the standard table (above) per each cargo type. Minimum cargo unit shown/transported is 1m3 and demand/sales would be done in 1-unit increments like passengers (or perhaps 0.5?). In the demand charts the amount of service/capacity supplied by players with pax+cargo combination planes would assume that pax seats are all sold, and the remaining space is allocated for freight (= the minimum possible space the plane has left). At the route editing/scheduling interface players cannot and do not need to adjust anything separately (apart from cargo pricing if they like) since the system will automatically allocate remaining cargo space from each flight to cargo operations (see below). For cargo planes naturally it's a bit simpler ..
Cargo demand is to be generated by the new city based system which is not tied to airports at all. Light cargo comes from all areas where business, industrial or tourism exists (large population areas boost this too), with emphasis on business areas. Standard cargo is not generated by tourism, and only lightly by business areas but largely from industrial areas. Heavy cargo relies solely on industrial areas. Cargo output is boosted by island areas and poor infrastructure.
Demand figures will be presented in an own chart in the route planning page, below the passenger demand chart.
All airports can handle all types of cargo.
Cargo sales for flights will be allocated after passenger sale allocation - any remaining space in the aircraft will be used by cargo (however payload and range limits will need to considered - this may be complicated). For this we need to set up also the value on how much space the checked-in bags of the pax will take. We already know the total weight of all pax + bags in the current model. But I would update this so that pax weight and their checked-in bag weight is treated separately. Each passenger might not have a checked-in bag, depending on the type (domestic/intl/long) of the flight (some will have two, but we'll assume that people will have 0-1 bags only, the likelihood increasing the longer the flight is). Once the number of bags is figured we know the weight (each bag is assumed to weigh the same .. again a standard value, let's say 15 kg per bag [could be factored for flight length too]), and then we need to figure out the volume of them to know how much space is left for cargo (we know the total freight space of the aircraft). So we'll just have to decice a simple volume value for each bag (0.2 - 0.3m3 per checked-in baggage would be a good starting value based from the max measurements for hold bags allowed by airlines; let's assume 0.25m3 per bag).. This would mean that a fully sold 160-pax A320 with 75% of pax having checked-in bags (120 bags) would have 30m3 from its freight hold taken - and since total freight space for that plane is 37.41 m3 there's still some room for small freight to be carried. For cargo planes naturally this step is omitted.. Once the available cargo capacity is known, the available cargo flights/capacity are then compared in a similar manner like pax flights. Cargo will not mind of the airplane age or time it arrives or takes to get there (etc), but route & company image and such will be still factored.
The only problem with the above example is the preference between the cargo types. The 7.41m3 available in that example's A320 can be used to carry standard and small cargo - but how should the system choose what to take? (of course each cargo type would have a minimum size - standard cargo could need for example at least 3m3 space before anything can be carried?) ..probably easiest is to prefer always the highest cargo class first, and then fill up the rest with the next if more space is left. This way the player doesn't need to worry about this either.
The 'cargo carrying potential' for each plane/route would need to be displayed in the route editor or somewhere else. [how?]
Income statement (etc) will have own lines for each type of cargo.
(Initial testing will be conducted with cargo-only planes and belly cargo is part 2. In the future, if more data is collected, freight conversions of pax planes are possible - a very limited data set exists already. Combiplanes / configurations can be also thought later.)