Interestingly I’ve yet to do this once on any flight, and in some maybe 20+ flights I’ve never seen the aircraft drift off of the flightplan. However my flights have all been <500 miles and in Europe or US. I haven’t ventured to Australia yet though. Is it maybe an extreme North or extreme South type thing where the IRS becomes less accurate?
I’ve been guilty of that as well and just clicked “align irs…” just assuming that the “loss of irs precision” warnings was down to it being a old aircraft.
Mate, cannot wait for you to venture down to this part of the world…
Definitely aim to do the Queensland/Brisbane flights asap as they, Alliance are fast withdrawing their fokkers from service.
Then head on over to western Australia.
Download
Cloncurry
Emerald
Mount Isa
Moranbah
Weipa
These are all fantastic freeware airports and buy yourself Brisbane airport…
Then download the silver fokker 70 bullet and the pink rocket
Yes I do that before the flight. I usually use the specific data from navigraph, otherwise I right click in navigraph on my plane and it tells me my coordinates.
On long flights over desolate terrain out of range from VORs the accuracy degrades
It’s also happened over Iran. So basically anywhere big enough without a lot of airports.
At the bottom of the PROG page in the fmc you will see two radio stations. They get autopopulated. Sometimes it’s empty.
My hunch is that when they’re empty for too long the degradation occurs and the message on the fmc appears about low precision or something like that.
Sounds plausible. I’ve only seen that message appear once and briefly. But like I say I’ve been over dense areas in Europe mainly. The most sparce place I’ve been flying over is the desert of south west USA, but probably still good for navigation aids. Maybe I’ll go try some more remote area.
There is some discussion on NAV accuracy here, note also the point about Align IRS appearing twice/‘unaligning’ - may be worth checking.
I think I understand why it degrades, I was wondering if it would kick off NAV eventually (or if i had done something wrong) and if there were any other tricks than just trying to tune in VORs.
But I guess it’s part of the fun of flying an older airliner, that you can run into situations like these.
I’m really enjoying this jet.Just Flight did an amazing job.
Early morning takeoff from Cairns to Groote Eylandt. I reckon there might be some dead spots along the way here too
In effect Inertial navigation is just dead reckoning - using accelerometers. But there is no way for a dead reckoning system to know its initial (starting) position.
You can easily spend your whole life or career understanding the intricacies of inertial systems - there is a very good technical overview/history of inertial navigation here for anyone interested.
We’re aiming to release the next update/upgrade (v1.2) by the end of this week. We’ll share the change log shortly.
Many thanks and this aircraft it’s, really amazing.
Are you doing this in the FMC REF->NAVAIDS section?
On the PROG page, at the bottom
I’ll need to try that out on the PROG page.The REF->NAVAIDS page has ability to enter a VOR frequ, lat/long, elevation and after entering a VOR data there this morning I could swear my LNAV moved ever so slightly like it had just calibrated something, but I have to say I wasn’t off LNAV course to begin with, so I’ll need to retry.
EDIT: I don’t know if you’ve seen this already, but VOR Tuning section has a paragraph on “Navaid Remote Tuning functionality that automatically tunes navaids throughout a flight to correct the IRS position”
Like you suspected this likely explains why you are seeing IRS inaccuracies in areas with no VORS /navaids.
Yes that’s what I’m seeing. Sometimes the auto nav doesn’t find a VOR but then I’ll enter one manually. And like your link describes, CLR on that field turns it back to automatic mode again
Have you tried the latest Freeware Fairchild Hiller FH-227? It is superb. No cabin, but the cockpit, sounds and handling is amazing.
Mate I haven’t but I love the freeware F27 which reminds me..
I haven’t flown that since the developer updated it to work on msfs2024.
I absolutely love that freeware F27
New one is by same guy, the FH-227 is the stretched version. BUT he’s done a new higher res cockpit. It is superb and FS2024 compatible.
Mate, I will definitely download it and give it a go.
Absolutely love that distinct darts roar I remember fondly as a kid when they pull back on the throttle
A question for Fokker 70 and 100 owners: are you able to update the Navigraph data to the latest AIRAC 2607?
No matter how many times I update both aircraft using Navigraph Hub, as soon as I close and reopen it, it prompts me to update the data for both Fokker versions again.
Update : I just took a look at the Navigraph forum; they are aware of the problem.
Hi, is this still on schedule?