Standby RMI

[Hardy Heinlin]

Good morning,

if I may, here's a question for those who have standby RMIs in the fleet. This may be airline specific.

When a VOR is tuned and the VOR pointer is operative, what will happen when the HDG REF is (manually or automatically) switched from NORM to TRUE?

a) The orange HDG flag appears
b) The orange HDG flag and VOR flag appear
c) No flag appears


As always, any hints are appreciated.

Thanks!


Cheers,

|-|ardy

[delcom]

Hi Hardy,
as long as there is no NCD,  invalid data, or failure present, there should be no flags at all regardless of heading reference switch position.

IRU R or IRU C will supply heading input, bearing data comes from L and R ADF and VOR receivers. When you switch to TRUE, the RMI will display it accordingly.

cheers,
d

[Qavion]

Hi, D, is this from training notes, personal experience or the AMM? : )

I ask because I tried selecting TRUE on an Atlas 744 a few months ago and the VOR and compass flags appeared (ADF doesn't require a heading reference). This disagrees with the Atlas AMM description (checked today).

Anyway, I'll recheck my findings when the opportunity arises ; )

Regards,
Q>

[Hardy Heinlin]

Hi all,

I conclude that also the behaviour of the ISFD heading (IRS L) regaring NORM/TRUE reference is then company specific: Either the ISFD compass card moves like the standby RMI compass card does, -- or it always stays in NORM and the RMI shows flags.

I think it would be a messy cockpit if some instruments are MAG and others TRU. Either all or nothing, i.e. switch the other instruments to the same mode or put a flag on them. No?


Cheers,

|-|ardy

[Qavion]

Our cockpits are already messy : ) .... The ISFD on our ER's doesn't change to TRU (at least not with the manual switch), but the ND's do. We no longer have RMI's (They are still mentioned in the current ops manual, but they  don't go into sufficient detail in this area).

According to the schematics, the NORM/TRUE switch has a direct input to the RMI. After further investigation, it appears that the IRU sends both TRUE and MAG to the RMI on an ARINC 429 Bus. Moving the NORM/TRUE switch selects MAG or TRU inside the RMI.

I guess that the NORM/TRUE also sends a signal to the EIU's or IDU's (rather than the IRU's) for changing the compass cards on the displays?

Regards.
Q>

[John Golin]

Our cockpits are already messy : )

I remember some of the pics of the mess...

I couldn't handle having to work in that environment and not being able to clean it!

[Hardy Heinlin]

Hmpf, another airline option.

Anybody else whose ISFD cannot be switched to TRUE heading reference?

I think this is not worth another option checkbox, it should be fixed in one specific way, but in which way? :-)


Cheers,

|-|ardy

[delcom]

Hi, D, is this from training notes, personal experience or the AMM? : )

Regards,
Q>

It was from memory...
Next time I'm near a bird equipped with an RMI, for sure I'll do a quick check.

regards,
d

[delcom]

Meanwhile...I've checked all of my documentation regarding RMI's. This includes several airlines and their own AMM's and SSM's. Also checked a CMM just for the flags. All of them (to my understanding) gave the same info...HDG REF switch selects MAG or TRU on the RMI. Found no evidence of triggering the flag drive by means of heading reference transition.

P.S: actually now I'm anxious to find an RMI that shows flag(s) when I switch to TRUE...lol.

BTW, nice screenshot Hardy.

sincerely,
d

[delcom]

Hardy,
watch the "weight" of the vertical separator line on P2-4 lightplate. That line should be as thick as the rest of the separators on your overhead (which you've already painted correctly, btw). One more little thing...the to circles around S3 and S5 under no circumstances may touch each other.

with respect,
d

[Hardy Heinlin]

Thanks for the tips.

P2-4 on the overhead? Where is it?

...

S3, S5, ... do you mean the HDG and MLS switch circles? I have no room left to get them apart.


Cheers,

|-|ardy

[delcom]

Panels...
P1 is driver side, P3 is passenger side. P2 is between them.

P(anel)1-1 is driver's clock, RMI and source select.
P1-2 is the two DU's.
P1-3 is display select.
P1-4 is the area for the brake pressure and optional autobrake selector.

P2-1 standby instruments
P2-2 UPR DU
P2-3 gear handle area
P2-4 EICAS control

P3-1, 2, 3 and 4 are similar to the driver side (mirrored)

Then there are more P numbers in the office. Yes, S3 and S5 are the HDG and ILS/MLS switches (on P2-4).

regards,
d

[Hardy Heinlin]

Passenger side :-)

P2 is known, I just didn't know from memory the numbers after the dash :-)

Do you have a close-up photo of the MLS switch?

This one is small, but the circles look like they touch:
http://img.photobucket.com/albums/v302/BritPilot777/SanFrancisco095Medium.jpg

Hope you have a good zoom.

Thanks,

|-|

[delcom]

A loooong time ago I made this drawing. Here you can see a P3-1 and a P3-4. The module in the background is a fuel control panel.

regards,
d

[Hardy Heinlin]

Nice brush stroke, looks very artistic.

Some day I'll be making some experimental drawings of some flight deck parts using some 14th century copper engraving style ... just to see how a modern industrial part would look like if it had been drawn by a medieval copper engraver.


|-|

[Hardy Heinlin]

This one has no line at all and has more free space:



I can't find the photo that I used as a reference, I think it had a line. Or I thought it had a line and I added one myself ...


|-|

[Peter Lang]

It has a line. I found this pic on my harddisk, but I do not know the source anymore.




Hope this helps
Peter

[Hardy Heinlin]

I think that's the one I have used, Peter :-)

Perhaps I made the line thinner to get at least the middle part more authentic and made a bigger compromise with the circles. Problem is, my circles must not touch the switch heads for bitmap/vector "sandwich layer" reasons, otherwise I have to spend some additional time with programing that specific area. Second question: Why is it important that the circles must not touch?


Cheers,

|-|ardy

[Qavion]

Hmpf, another airline option.

Anybody else whose ISFD cannot be switched to TRUE heading reference?

I noticed yesterday that with only the Left IRU operating, and in ATT mode that when I switched from NORM to TRUE, heading info was removed from the PFD & ND, but the ISFD continued to operate as if nothing had happened.

Rgds
Q>

[delcom]

I thought ISFD's were MAG only.

cheers,
d