Re: [Flightgear-devel] Typical NAV system errors

[David M. <dav...@gm...>]

>From personal experience, I'll also add VOR scalloping, especially over
populated areas (with lots of radio interference). The VOR/DME 09 approach
into CYND in real life can have you weaving 10° left or right of course as
you fly low over the city, even at the start, when you're still close to
the YOW VOR. Scalloping is very common as you reach the limit of the VOR's
coverage range, even when you're up high and not over a populated area—if
you set the autopilot to follow the CDI hooked up to the NAV radio rather
than a GPS, you'll fly a gentle slalom course all the way to the navaid,

D

On Thu, 5 Jan 2017 at 08:40 Thorsten Renk <tho...@sc...>
wrote:

>
> I've now managed to streamline a first version of state vector propagation
> during Shuttle approach. I've used the following error estimates (I'd be
> obliged if people who have some more experience can eyeball and check
> them):
>
> * for a gyroscopic inertial guidance system I found in several places
> drift rates of ~ 2 miles/hour. I've modeled that via random noise on the
> accelerometers, leading to velocity errors and hence accumulating position
> errors.
>
> * for TACAN, I found as figures of merit quoted 0.5 deg in azimuth, 0.2 %
> in range with a minimum of 0.1 miles range error
>
> * for the Microwave anding system some 20 ft horizontally and 5 ft
> vertically
>
> * for barometric altitude measurements, instrumentation errors of 80 ft at
> 10.000 ft altitude are apparently considered acceptable by the FAA, I've
> used an error range of 50 ft every 10.000 ft (plus whatever the
> calibration error to ground pressure is, but that's not a range but an
> offset).
>
> If anyone has better numbers, I'd be much obliged to know.
>
> Best,
>
> * Thorsten
>
>
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