A320 Triple IRS Failure
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A320 Triple IRS Failure
A320: In case of a Triple IRS Failure in flight (if possible) the NAV accuracy reverts to LOW. Do we continue navigation using GPS data or raw data ? I personally suppose that this scenario brings the pilots to fly by raw data only. Is the A320 approved to fly by GPS's only without any kind of NAV redundancy ? ... Thank you and Best regards
by captain87
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I don't know anything about the airbus. But wouldn't this scenario mean you would loose all attitude+heading information??? Even if you could revive this info by putting it in manually you would still need to land asap...........
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re from captain87
Yes, all attitude + heading informations are lost even if we can perform a recover anytime by setting them manually (IRS sel from NAV to ATT).
This thread doesn't keep in mind the air data field but navigation.
Cheers
This thread doesn't keep in mind the air data field but navigation.
Cheers
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Well so your back to gps or raw data vor/ndb/ils tracking. I would suggest using both... you never know what those americans are doing to the signal ;-)
I dont really understand the problem... you wouldn't / couldn't proceed all the way to destination, unless you are very close to it.
Its not yet allowed to fly a gps approach so you would need rawdata for this. With regard to airways, I think you could use gps only.
I dont really understand the problem... you wouldn't / couldn't proceed all the way to destination, unless you are very close to it.
Its not yet allowed to fly a gps approach so you would need rawdata for this. With regard to airways, I think you could use gps only.
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re from captain87
Dartagnan,
ILS + VOR are still working ... we navigate by using raw data. ... Are the GPS's still serviceable ? ... Could we still use them for navigation ?
I didn't succeed to find this information on FCOM's .
Thank
ILS + VOR are still working ... we navigate by using raw data. ... Are the GPS's still serviceable ? ... Could we still use them for navigation ?
I didn't succeed to find this information on FCOM's .
Thank
In case of a Triple IRS Failure in flight (if possible) the NAV accuracy reverts to LOW
GPS recievers are still serviceable but their output is used to feed IR part of the GNADIRS only (in order to calculate hybrid IRS-GPS position). There's no bypass or override that can send GPS position to the FMGSes - see scheme in FCOM 1.34.15. So with triple IRS failure (assuming complete failure, so ATT is lost too) in flight you're down to hand flying on stby instruments, in direct law. VOR/DME/ADF/ILS are still operative, but what will ND look like is anyone's guess as you will have no HDG data to allign your compass rose with your heading.
But don't loose any sleep over it, triple IR fault is considered to be so unlikey by the Airboos that there's no procedure to deal with it, unlike single or dual failures. Also all of the dual IRS failures I've heard of, developed after the airplane was dispatched with one IRS inop.
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re from captain87
Clandestino,
thank you very much for your answer that is what I expected to know.
In fact there aren't procedures dealing with a Triple IRS Failure in PRH.
With the loss of three IRS, are the ADIRS still capable of providing AD (Air Data Informations) without IRS ? ... Are both GPS's still using their MMR (Multi Mode Receivers) to "supply" the ADIRS ?
That was I asked in this thread. Thank you at all.
by captain87
thank you very much for your answer that is what I expected to know.
In fact there aren't procedures dealing with a Triple IRS Failure in PRH.
With the loss of three IRS, are the ADIRS still capable of providing AD (Air Data Informations) without IRS ? ... Are both GPS's still using their MMR (Multi Mode Receivers) to "supply" the ADIRS ?
That was I asked in this thread. Thank you at all.
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I personally suppose that this scenario brings the pilots to fly by raw data only.
- How are you going to use "Raw Data"? No ADIRS = no ND as far as I can see, and even if fitted / serviceable, no DDRMI
- How are you going to use GPS? You will have raw Lat/Long information only I think - great to try and "navigate by"
NoD
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Should we proceed for visual ?
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re from captain87
Ok, so it depends on situation. Obviously visual navigation should be avoided anytime the IRS's are lost, expecially if flying within crowded airspaces.
Psychophysiological entity
you're down to hand flying on stby instruments, in direct law. VOR/DME/ADF/ILS are still operative,
Luxury! We used to dream of having all that stuff.
VOR requires valid heading to show a valid bearing on a RMI, for the deviation bar to work against a pre set course a valid heading is also required.
ADF does not REQUIRE a valid heading to indicate correctly as it always indicates relative bearing, however, conventionally, this is usually in a RMI or HSI presentation which of course needs a heading input.
My (engineering) opinion is that you wold be up the proverbial creek wihout a paddle and vectors for visual on stby instruments with perhaps a little assistance from the NDBs is the only solution.
ADF does not REQUIRE a valid heading to indicate correctly as it always indicates relative bearing, however, conventionally, this is usually in a RMI or HSI presentation which of course needs a heading input.
My (engineering) opinion is that you wold be up the proverbial creek wihout a paddle and vectors for visual on stby instruments with perhaps a little assistance from the NDBs is the only solution.
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Thanks Wodrick. I do know how VOR and ADF usually work, and was asking in the context of the thread. It has been suggested that VOR and ADF will still be available after loss of all 3 IRS on a A320.
I was just curious how that could be.
I was just curious how that could be.
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erm....I might be wrong but in this situation surely you would be down to the use of the ISIS and the stby compass...In direct law! The ISIS only has LOC and Glideslope info. No heading info ( well it is an option but I have never seen it), so you would be relying on vectors to an ils / loc only approach. Or an SRA or visual I suppose.....good luck!!
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re from captain87
It's quite ridicolous for an A320 being flown visually ... Direct Law - No NAV Info - No Attitude Info - No Heading Info ... if anything else might occur it would be a right way for the pilots to pull the "ejections seat" handle ! I think that flying by Standby Compass with the A320 would be very hard anyway ...by captain87
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Captain 87.
The airbus is an aircraft like any other, if it all goes wrong then you revert to basics. You would get attitude info on the isis along with airspeed and altitude. You also get glide and loc info. As well as that you have the standby nav instruments for VOR/DME/ADF info, so all in all you are just reverting to a jet powered seneca.
My point in my previous post, which having reread didnt come across, was that at the point when it all goes dark and you are relying on stby instruments maybe an ILS would be the most desired choice.....
The airbus is an aircraft like any other, if it all goes wrong then you revert to basics. You would get attitude info on the isis along with airspeed and altitude. You also get glide and loc info. As well as that you have the standby nav instruments for VOR/DME/ADF info, so all in all you are just reverting to a jet powered seneca.
My point in my previous post, which having reread didnt come across, was that at the point when it all goes dark and you are relying on stby instruments maybe an ILS would be the most desired choice.....
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JJ737
'isis' ?? But yes, A320 series do have tiny Sby AI, Alt and ASI...
Really? My understanding is that the DDRMI (Sby DI thing) is powered by the IRS output, so no IRS = no DDRMI = no ADF/VOR etc.
Bear in mind in e.g. our fleet, most DDRMIs have been "inop" for years, and the newest aircraft do not even have them fitted...
NoD
The airbus is an aircraft like any other
You would get attitude info on the isis along with airspeed and altitude
you have the standby nav instruments for VOR/DME/ADF info, so all in all you are just reverting to a jet powered seneca
Bear in mind in e.g. our fleet, most DDRMIs have been "inop" for years, and the newest aircraft do not even have them fitted...
NoD