I don’t think WAAS/EGNOS improves GPS altitude accuracy but it seems almost nobody actually knows
SBAS of course improves integrity – it is damn hard to shift or otherwise fake the GPS position if you have the extra data from the ground stations and sent to you from a geostationary satellite – but that’s a different question.
The precision of the GPS AGL is to the nearest 20 feet and I would expect the normal 95% accuracy figure would be +/- 20 feet. The runways at the airport have surveyed threshold altitudes of 666 and 662 feet. I am off the runway to the east by about 500 feet, so can only guess what the precise elevation is. Assuming it is 670 feet to the nearest 10 feet, the G5 is showing a smidge over 680 feet (+10 feet) and the G500TXi is showing a little over 650 feet (-20 feet), they are all in fair agreement.
It’s a stupidly designed website, expecting people to waste their life watching videos on the home page… but deeper down you find this local copy which tells you it is a laser ranging device.
Fairly obviously it won’t be any good in IMC although you should not have IMC below you at 100ft AGL
Installation_Users_Guide_LS_100_X_A3_pdf
Interesting idea but what does it solve, with a 100ft max range? Learning how to flare using it, rather than visually, is going to be a whole new learning exercise.
The GPS based solutions obviously use a terrain database, which is quite low resolution. GPS altitude accuracy is not bad – 10-20ft is common even with my KLN94 – but a say 20ft error at night will make the difference between landing, and smashing the plane up.
@Ultranomad, do you have any knowledge about the questions in post 5 about the RA17GA?
@lionel, I only spoke to the guys a few years ago at Friedrichshafen. Their previous model, RA-01GA, is available from e.g. Sandelving. No ETSO, merely a certificate of conformance, but you don’t need an ETSO as long as you use this equiment merely for advisory purposes.
Peter wrote:
it is a laser ranging device.
When it’s laser based (and therefore directed with an extremely small beam angle), another interesting question is how they do the pitch angle correction that can be a relevant factor at the phases of flight below 100ft …
What do people think of LHS (Landing Height System)? this sounds better version, the feedback on previous ones installed was not good: telling you 20ft, 10ft at FAF in IMC
On missing calling PIC “retard”
Is it needed in GA? I suppose the 500 and 200 are useful in IMC, but below 200 shouldn’t all GA be visible with the runway?
A radar altimeter seems like a lot of expense for little utility in GA.
Definitely not worth the money in my Guepard or the club Jodel
It will certainty help on night landing and tells you to lower the gear, I think it’s a good saving compared to Gear Up landing?
If it tells you 500ft while you are in clouds, I would take it seriously
It’s cool: pax take it seriously and does not call you ‘retard’
Price is 1AMU (maybe N-reg only)
I am not keen on installing one
The utility is very relative, I never felt synthetic-vision was useful? then one day, I landed using it once in C172S, I learned that one Cirrus SR22 that landed 45min after us crashed, METAR was OVC003 & RVR1300