looks like 2:1 now homework not homework :D

@ymb1 the system doesn't allow me to request the tag synonym because I don't have enough rep in that tag. I need more than 5 rep. I am sure I have more than 5 on that tag...

@DeltaLima the tag is now populated, takes time I guess -- try again please: aviation.stackexchange.com/tags/rnp/synonyms thx

the synonym so you don't have to scroll up: required-nav-performance

@ymb1 this time it works. Thanks for initiating this!

thanks again!

@Jamiec FYKA: aviation.stackexchange.com/tags/… (for some reason the list is empty on my side, but there should be something there) thanks!

and the relevant meta post: aviation.meta.stackexchange.com/a/4134/14897

judging by the description: how is faa-approval different from pilot-certification?

@ymb1 it sounds like faa-approval needs help then, because I suspect the former would make more sense for things the FAA has to supply approvals for specifically via LOA, OpSpec/MSpec, and so on

@Shalvenay had already made a meta post, but I'll add your comment, thx

hi @DeltaLima -- before I ask a dumb question, both answers here, say you can lose SBAS and still have RAIM, only downgrade is LPV approaches. That's fine -- But looking at that slide here -- why does having SBAS then negate the preflight prediction check? when losing RAIM sends the whole thing out of whack

by whole thing I'm referring to RNP integrity(?)

There is no such thing as a dumb question I've been told. And this one certainly isn't. The slide refers to ADS-B integrity, which requires a different integrity level than RNP. The probability of not achieving the intergity level required for ADS-B is significant for TSO C129 (SA ON) installations, quite low for TSO C196 (SA Aware) installations and insignificant for TSO C145/146 (SBAS) installations.

The preflight check is a different on than for RNP

@ymb1 ^^^

thanks @DeltaLima -- how is an ADS-B integrity checked preflight? I would have thought that's the RAIM's job

I posted the question btw, if you have the time whenever to answer it, given my latest sub-question above :D

@ymb1 I have started to write an answer. RAIM is not an easy topic because the concept of integrity is more abstract than accuracy, for which most people have a good feeling. I will try to create an in depth answer, but it requires a lot of drawing and therefore some time. I hope I will get to it tomorrow. I posted a short answer now, but I am not happy about the quality of it.

much appreciated, I am only asking out of curiosity btw, you can keep it simple, since that's easier, and if I have any requests for clarification, I'll let you know

If I understand correctly, ADS-B is more stringent compared to RNP?

@ymb1 RAIM & integrity question keep popping up here occasionally. I would like to write a high quality answer that finally puts it to rest. Thinking about it, probably I could write a few Q&A's to address the topic in depth and link to those from the answer to your question.

sounds great, can't wait :)

@ymb1 Yes, RNP en-route requires 4 NM integrity bound (10^-5 /flight hour) IIRC, and RNP approaches require 0.6 NM integrity I believe. The FAA requires ADS-B to transmit positions with an integrity bound of 0.2 NM or less.

yikes

This is why SA-On receivers are totally unsuitable for the ADS-B rule of the FAA.

but understandable, of course with the benefit of hindsight, right now it's duhhh, a minute ago it was huuuh? :D

but still how SBAS works around that, I'm eager to know

I'm guessing the combined corrections + say RNP of .6 does the trick

or even >.6

SBAS does a few things: 1) it is an extra GPS satellite at a fixed (geostationary) position. 2) it supplies parameters for a error correction model that improve the accuracy of GPS signals received by the receiver, 3) it does its own integrity monitoring of the whole GPS system and reports any issues with GPS within 6 seconds to the WAAS receivers.

so, auto-RAIM

👌

on steroids

hehe -- they should have named it SB-RAIM, would have saved a ton of head scratching

which raises one of my questions: why is it that at least in the US, SBAS-capable equipment and SBAS-reliant (LPV or LP) approach minima are apparently mostly the province of GA operations? you'd think the airlines would want the extra help SBAS provides to GPS, especially in the bad old days of SA...

@DeltaLima if you include that message -- chat.stackexchange.com/transcript/message/57330946#57330946 -- in the answer, for the time being for the non-chat readers, I think it'll be awesome

@Shalvenay Gerry hinted at the reason for that here aviation.stackexchange.com/a/84602/14897

> The air transport market wasn't very interested in SBAS, they tended to lean towards GBAS (if they cared at all.)

money

a tale as old as 1994 aviation.stackexchange.com/a/50083/14897 -- :'( I miss Flight's archive

> Airlines are reluctant to make the necessary investment until civil-aviation authorities (CAAs) make their intentions clear. In a classic chicken-and-egg paradox, however, the CAAs say that they cannot go ahead until they are certain which equipment the aircraft will carry in future. Exasperated service providers are reduced to pleading with the user community to do something, at least.

@ymb1 included it.

super, already +1ed, will accept now, and will eagerly await your Q+A's :) super thanks DL

@DeltaLima the US government doesn't own the WAAS satellite(s) right? compared to the GPS ones -- i recall reading it's an Iridium one

must be a nice rent to Iridium :D

@ymb1 Iridium is a LEO constellation. If WAAS is hosted on a commercial communication satellite, my guess would be inmarsat.

From wikipedia: The space segment currently consists of three commercial satellites: Eutelsat 117 West B, Telesat's Anik F1R, and SES-15.[10][11] A fourth satellite, Galaxy 30, is set for launch in 2020.[12]

(Y) that's it, and Boeing, eutesat

one launched by spacex in '16, sweet

BTW, Iridium hosts the ADS-B receivers of Aireon.

yep, came back to me now

That was a nice SpaceX job as well

they launched 1 or 2 GPS sats too

market disruptor at its best, love it

yes. Just a few days ago I saw a new train of ~60 Starlink satellites passing overhead early morning. Don't know whether to love it or to hate it.

astronomers hate it

It's changing the view of the night sky for good.

Starlink is tapping into the big market segment that is ignored by the land-based ISPs, whether availability, speed, or data caps -- the beta users on reddit are loving it

I think I read they plan to Starlink-connect commercial planes as well

what data rates are they achieving, do you know?

just a sec

example from reddit.com/r/Starlink

That is better than what my ISP is able to provide me...

> Elon Musk: SpaceX's Starlink will connect planes, trains and automobiles zdnet.com/article/…