When someone pulls the plug the system degrades through a number of levels - we have multi radar, parallel processing of data, alternative power etc.- so we should have plenty of warning before the picture remains frozen and an print out of traffic is produced: by this stage no more new traffic should be entering the system.
Having said that, of course it is possible for a collosal failure or external action to take the system out In this case strips would provide some degree of back up, provided they are 100% up to date - it only needs 1 missed FL update Can you guarantee your strip marking?
In any case, do you think that anybody would be able to restore procedural separation anywhere in W. Europe with today's traffic levels. In such a case I think TCAS would be the most effective separation tool
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Lon More
More than just an ATCO