grimey wrote:Night-Hawk wrote:
The computer network in the Dreamliner's passenger compartment, designed to give passengers in-flight internet access, is connected to the plane's control, navigation and communication systems, an FAA report reveals.
Am I the only one wondering why the hell Boeing would do that?
Weight I suppose and redundency. You put in full blown network in the plane with dozens of different ways that data can get from any one place to any other in the plane. They probably are using a high speed data network over optical fibers that run a myriad of different routes through the plane. Data can get from a controller to the device being controlled by numerous different routes when things go wrong. Properly designed and implemented it would result in an extremely robust system that would only stop working when there were no more routes for the control data to reach the things being controlled. Also no cross talk problems, just good clean digital signals for sensors etc.
Now there are lots of ways you can isolate these logical networks depending on your definition of 'touch'.
You can use a bundle of fibers and use only some of the fibers for crytical systems.
You can use different wavelenghts of light on the fibers for different systems.
You can use different time-slots on the wavelengths on the fibers for different systems.
or you can assign different 'codes' to the data that flows such that control coded data gets priority.
Properly designed all of the above systems work and while technically the networks 'touch' they are isolated. These are referred to as VPNs (Virtual Private Networkis) in the networking world and are commonly used to isolate banks/stock trading/hospital or other critical data from a larger physical network without having a physically separate network.
The advantage of the last approach is that you won't end up with your control not working as the plane goes down but the video games are all up and running. The system would literally take-over the less important traffic on the network to get its control through.
These are all common approaches to sharing a network for various types of traffic and have been around and working for many years. ... however in the context of a plane, you have to wonder if its worth the weight savings to take those kinds of risks, even if the risks can be minimized by good engineering.
I sure hope whatever they do that they have a few good old fashioned cables to tip spoilers etc. so that some degree of control is always available even without power.
Peter