Brian 48Nav wrote:
Declination?
I think you mean variation, Beagle!
Probably - a lapse in terminology through having to consider 'station declination' and actual MagVar when considering Place/Bearing/Distance from various ground-based beacons which applied fixed declination values to transmitted radials rather than actual MagVar.
Trying to work out how to cope with an aircraft which didn't have a 'north sense' switch and which operated in northern Canada using magnetic values displayed on the instruments whilst the INUs worked in True was....interesting. Particularly without the benefit of a food-powered navigation system (in his case...lots) such as Tengah Type!
Originally, as it was only ever expected to fly on UK AARAs, the VC10K flew with Mag values displayed to the pilots. This could be changed to 'True' by turning an 'HSI' switch on the centre panel. Except that it wasn't really 'True', it was Mag minus whatever MagVar the navigator had set....
I only tried the switch once (with a very experienced navigator on the crew) over Canada - when turned it did so reluctantly and subsequently kept rotating! I managed to get it back into 'Mag' and vowed never to touch it again!
Things became much more logical after the VC10K was fitted with a GPS/LINS to augment the Carousel - and we also had the luxury of an autopilot 'NAV' mode. But the Mod was a typical cheap botch-up as the navigator didn't have a repeater display to see what the pilots could see - and the pilots (perhaps wisely) couldn't make any nav inputs (except verbal requests to the navigator!).