Hi,no, it's not about the taxes :)Two things I noticed:1) After failing both IRU's and removing the faults, I wasn't able to get them into ATT mode. I turned the mode selector to OFF, waited for the align light to extinguis and selected both modes to ATT. You should be able to restore basic PFD information in this case, but nothing happened. Well almost nothing - at some point I had a V/S indicator but that's it.2) With both IRU's dead, the HUD had a GS indication (note, both GPS recievers were also killed - not that it would matter though)RegardsMark

I noticed that some failures (like for brakes) also if cleared will not restore the system functionality. A flight reload is the best thing.About the second, I didn't tried so I cannot tell you.But, we are speaking about both IRS aligned in ATT mode while inflight?What about DMEs? were also failed? The primary GS indication comes from FMC, the FMC will use all avaiable data (IR included), and DME DME (or other radio measurements) is sufficient to detect the ground speed.

Hi Andrea,yes, both IRU's failed to enter ATT mode while inflight.Regarding GS data:How would this work with only two DME's? You can't pin-point your position based on two DMEs. On basic aircraft a GS indication will only be valid if you are flying directly toward or away from a DME station.The HUD was showing GS indication extremely accurately and with a high update rate - not something you'll achieve with DMEs.In the big sim, if you loose both IRU's and both GPS's, the FMC will have no idea where you are, let alone your ground speed. Luckily, I don't know what happens in real life :)RegardsMark

I tried to fail irus and to fail all the nav sources for position update, including DMEs and a total FMC failure. GS was still present only on the HUD, so it is a little bug.PMDG fixed few updates ago a wrong ATT alignment with PFD and ND working when in ATT alignment, there was also no chance to put manually the heading.I've not tried the failure (neither I don't know if you could fail only the inertial part of the IRUs) but, pmdg added the needing of aircraft leveled to let the ATT to align.I checked the functionality sometime with SP1b, I was able to align them from OFF (no previous failures) but it was hard to do if winds are present.

Hi, please tell me why the IRSs depend on the PMDG Options IRSs Selection and not on the selection of the IRSs Switches. With the realistic selection on the pmdf options, If i position the IRS Switch to Nav then Align then Nav, it performs a full alignment and not a Quick Align that is what i have commanded. If i select quick align on pmdg options and command a full alignment to the IRS it performs a quick alignment. Thank You.

To the OP, I experienced a problem with the alignment once but I had landed at an airport and shut down to cold and dark. Then I loaded a different airport and tried to start up from where I left off but was unable to get the IRS to align until after I loaded the PMDG C and D panel state. Not sure if this is a true bug or that I'm doing something wrong. For anyone that this happens to, just load a panel state, no need to reload the flight.

VAE,the IRS can compute a rough latitude by itself without needing input data. This calculated latitude is compared to the stored latitude, which was stored when you shut down the aircraft. If there is a largish discrepancy between the two values, the IRS won't accept the value you input through the CDU. You can override this feature by inputting the same position a second time.Good on PMDG if they modelled this! I haven't tested this yet but it could explain what happened to you.How big is the tolerance in pitch and roll angle during ATT alignment in flight? To be honest, I don't know how tolerant the real IRU's are in real life. Usually, if we loose an IRS in the sim, it's completely dead.Mark

Hi, please tell me why the IRSs depend on the PMDG Options IRSs Selection and not on the selection of the IRSs Switches. With the realistic selection on the pmdf options, If i position the IRS Switch to Nav then Align then Nav, it performs a full alignment and not a Quick Align that is what i have commanded. If i select quick align on pmdg options and command a full alignment to the IRS it performs a quick alignment. Thank You.

To do a quick alignment you need the IRS already aligned. There is no shortcut for the alignment, 10 minutes...After that, a quick alignment is allowed, it will use the already aligned unit and will reset the data to the new given position.No way to do a quick alignment from OFF.This is on the real, this is how pmdg works.

To the OP, I experienced a problem with the alignment once but I had landed at an airport and shut down to cold and dark. Then I loaded a different airport and tried to start up from where I left off but was unable to get the IRS to align until after I loaded the PMDG C and D panel state. Not sure if this is a true bug or that I'm doing something wrong. For anyone that this happens to, just load a panel state, no need to reload the flight.

Check the position, if you changed aircraft position without regenerating the flight and with IRS off, your last position is different from your current position. If the difference is between limits, it will align, if it is something not to much far, you can force IRS putting the same position 2 times.If it is completely wrong, it will give you error.Use GPS position or put manually the gate/parking position.

Hi, please tell me why the IRSs depend on the PMDG Options IRSs Selection and not on the selection of the IRSs Switches. With the realistic selection on the pmdf options, If i position the IRS Switch to Nav then Align then Nav, it performs a full alignment and not a Quick Align that is what i have commanded. If i select quick align on pmdg options and command a full alignment to the IRS it performs a quick alignment. Thank You.

The setting in the CDU defines how long will typically full alignment take.To perform a quick alignment, the IRS must be already aligned in NAV state (e.g. have not been turned OFF since last full alignment)

Quick alignment is refreshing the position of an already aligned IRS, not some kind of fast alignment from off. There's no such thing on the real aircraft, it always takes around ~10 mins if they're off.