This sort of thing will become more common. There is disconcerting confidence in the ability of technology to solve all humanity's problems. Air Traffic Control Authorities place increasing reliance on new technology to overcome congestion. We have already had 8.33 KHz VHF reducing the radio band seperation to just one third of human audio perception. Basic RNAV reduces track errors to within one mile while RVSM reduces vertical seperation to 1000 feet above FL290. These were all imposed as legal requirements before the necessary avionic equipment was designed, tested and certified in older aircraft. The belief seems to be that anything can be achieved as long as it is made mandatory. The TCAS experiment continues and I use the word experiment advisedly. (For those familiar with the technical side, consider the messy 'Gilham Code' AD focussed on analogue/digital conversion of altitude data for use in TCAS systems on non-digital aircraft.) EUROCONTROL will soon announce the introduction of rules to make RNP1/3 mandatory. ATC watcher's offset will be no use then, anything more than 750 metres will put you in the opposite lane as it were!
Is the equipment capable of these degrees of accuracy? I don't know and nor does anyone else. Although new deliveries of the latest models come ready equipped with the latest technology, most aircraft need major retrofit modifications. Not everyone has GPS (not as foolproof as many people think it is!) SatCom, ACARS or the latest Laser INUs capable of meeting the tighter RNP limits. Although equipment is already available and flight testing has been conducted on new built aircraft, long term equipment reliablity at the increased accuracy levels has never been established. Yet legal requirements will be imposed regardless, and in general by authorities that have no expertise in the details of installing and testing the systems.
The US Congress forced TCAS on the aviation world in the face of protests from avionic experts that equipment development would take more time. They have a lot to answer for now that they have established a trend.
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Through difficulties to the cinema