Of Duncan Bath >The logistics of changing Air Traffic Control from feet, miles etc. to SI >are formidable. Given the availability of SI and given the use of SI in >other jurisdictions provides considerable impetus to getting on with SI in >aviation. >I suspect that considerable thought and effort are being expended on this >issue. Along with all the 'nuts-and-bolts' problems of a changeover, >there is the lurking issue of SAFETY during (and for a time, after) the >changeover. > >The example of temperature readings suggests that, difficult as they may >be, more changes will be forthcoming.
One of the great skills is 'management of change'. The National Geographic was pro-metric but completely messed the transition. They had issues with some articles in metric-only and some articles in old units only, thereby managing to exclude all non-bilingual readers. The resulting backlash set back the cause 20 years and they are still falsely concluding that their (mismanagemed) attempt as evidence that it can't be done. Aviation clearly can't afford to mess it up. But it is an international industry. The US change from Fahrenheit to Celsius coincided with a change to using the international weather report format (METAR). Weather reports are something that pilots need from local sources. Although altitude is non-metric throughout the west, horizontal distance is metric in most countries. Some parts of the industry e.g. ATC, will therefore prefer to have a single measure. I know that some ATC personnel will speak in terms of inches and mm Hg depending on the aircraft. US pilots will be exposed to metric measures when flying on international routes. The safety argument is therefore in favour of a single measure for international flights. The UK has already made the transition to using metric for horizontal distances (visibility, runway length etc). Maybe the US could do this as a next step, at least for visibility which is a fairly rough measure anyway. UK Commercial pilots are obliged to demonstrate the ability to convert between metric and non-metric units. http://www.caa.co.uk/docs/175/srg_fcl_gid41.pdf If there is nothing similar for US pilots, then perhaps this would be something that could be introduced easily with a pro-safety argument. -- Terry Simpson Human Factors Consultant [EMAIL PROTECTED] www.connected-systems.com Phone: +44 7850 511794
