Sign in to follow this  
pkofman

anyone know what this means 2- questions 747 pmdg

Recommended Posts

1. When flying I have a green indicator in the pfd that says " irs 3 gps" it is green, The inertial systems are all ok , What does this mean and does it require action..2. When flying on a/p does the first office F/D also have to be engaged in addtion to the F/O . My deduction is that the first office f/d does not have to be engaged to use all of the autopilot functions if they are engaged at the captions station.Thanks Peter pmdg 747 cf-mmz

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

>1. When flying I have a green indicator in the pfd that says>" irs 3 gps" it is green, The inertial systems are all ok ,>What does this mean and does it require action..>>2. When flying on a/p does the first office F/D also have to>be engaged in addtion to the F/O . My deduction is that the>first office f/d does not have to be engaged to use all of the>autopilot functions if they are engaged at the captions>station.>>Thanks >>Peter >pmdg 747 cf-mmz1. It means that your IRS' are aligned and ready2. No- John

Share this post


Link to post
Share on other sites

1. Means that your navigation data is being updated by all 4 data sources- 3 Inertial units and one GPS, which is a good.>>1. When flying I have a green indicator in the pfd that>says>>" irs 3 gps" it is green, The inertial systems are all ok ,>>What does this mean and does it require action..>>>>2. When flying on a/p does the first office F/D also have to>>be engaged in addtion to the F/O . My deduction is that the>>first office f/d does not have to be engaged to use all of>the>>autopilot functions if they are engaged at the captions>>station.>>>>Thanks >>>>Peter >>pmdg 747 cf-mmz>>>1. It means that your IRS' are aligned and ready>>2. No>>- John

Share this post


Link to post
Share on other sites

Just a couple of flight director tips:-1) If you have both flight directors on and you make an autoland, make sure you disconnect both F/D's if you want to regain directional control of the aircraft once on the ground. If they remain engaged, the autoflight system tries to maintain the localiser signal to keep you down the center of the runway. I've been caught a few times trying to vacate, and then she steers back to the centerline ;)2) Same goes if you want to disconnect the autoflight systems during an approach and fly manually, you can't just disconnect the A/P, you'll have to disconnect the A/P and both F/D's.Finally just a small corection, the green IRS 3 GPS indication is on the ND not the PFD :(

Share this post


Link to post
Share on other sites

>Just a couple of flight director tips:->>1) If you have both flight directors on and you make an>autoland, make sure you disconnect both F/D's if you want to>regain directional control of the aircraft once on the ground.>If they remain engaged, the autoflight system tries to>maintain the localiser signal to keep you down the center of>the runway. I've been caught a few times trying to vacate, and>then she steers back to the centerline ;)>>2) Same goes if you want to disconnect the autoflight systems>during an approach and fly manually, you can't just disconnect>the A/P, you'll have to disconnect the A/P and both F/D's.>>Finally just a small corection, the green IRS 3 GPS indication>is on the ND not the PFD :(Thanks for the correction and the autoland is great, very cool when it works properly,, Peter

Share this post


Link to post
Share on other sites

Actually after an autoland you can turn the FD's on and off until your hearts content but you will stay on the centreline until you either overide or disconnect the Autopilot.You can disconnect the AP and fly manually but the FD will still give commands to fly the ILS if that is the approach you where flying.The FD and AP systems are independant but both are controlled via the MCP. For example if you which to sidestep from one ILS to another you need to switch off both FD's and disconnect the AP in order to do so.CheersSteve

Share this post


Link to post
Share on other sites

And also . . . That green "IRS 3 GPS" means that the IRSs are in what is called Triple Mix mode. That provides an averaged present position output. BUT, that Tmix'd output is being continuously updated (overwritten) by the GPS system. While the 3 IRU are theoretically providing the navigational basis, normally it's actually the GPS that is providing present position data for the FMC.Pole runs are fun way to watch the FMC 'fail-through' its various PP updating modes. Here's an old test flight: http://forums.avsim.net/dcboard.php?az=sho...ing_type=searchBut darn, the pictures are gone. I crashed head on into the FS9 polar force field and a got a shot of my contrails overtaking the airplane. I turned and 'heading selected' off the wall. I then skidded around circular force field until I was able to recapture my Lnav route that was coming out the other side. The ND showed it all perfectly. Lots of fun, Any FSX beta fliers out there. Did they get this fixed?

Share this post


Link to post
Share on other sites

I read sometihng in an airbus technical document that said flying the FD bars was not advised. It was either AP and FD or none in this guys opinion.Sounds weird huh? In the 747 I normally fly the FD bars up to 10,000 before I engage the AP and normally for the intercept and approach as well.Speaking of which, I fancy an impromptu KCLE-KJFK, haven't flown the Canarsie visual to RW13R in ages! Talk to you all later on :-)

Share this post


Link to post
Share on other sites

>And also . . . That green "IRS 3 GPS" means that the IRSs are>in what is called Triple Mix mode. That provides an averaged>present position output. BUT, that Tmix'd output is being>continuously updated (overwritten) by the GPS system. >>While the 3 IRU are theoretically providing the navigational>basis, normally it's actually the GPS that is providing>present position data for the FMC.>>Pole runs are fun way to watch the FMC 'fail-through' its>various PP updating modes. Here's an old test flight: >>http://forums.avsim.net/dcboard.php?az=sho...ing_type=search>>But darn, the pictures are gone. I crashed head on into the>FS9 polar force field and a got a shot of my contrails>overtaking the airplane. I turned and 'heading selected' off>the wall. I then skidded around circular force field until I>was able to recapture my Lnav route that was coming out the>other side. The ND showed it all perfectly. Lots of fun, >>Any FSX beta fliers out there. Did they get this fixed?>New Questions on thie same thread,Well I always thought the position data was coming from the gps, makes sense given the nav radios are both tuned to the ils and position is still on track as the intercept occurs.Some other questionsOne the way down i usually place the alt value lower than the calculated alt in the fms BEFORE the TOD circle . In this way the plane follows the vnav for alt-fix values, Does anyone else do this?Any other methods to ensure the plane follows the vnav path on the way downalso,Several times, on autoland I am lined up and I push Loc then App,, but the A/P trips and goes off,, that has me baffled ,,Seems to come out of nowhere.??ThoughtsPetercf-mzz ACA-10

Share this post


Link to post
Share on other sites

"1. Means that your navigation data is being updated by all 4 data sources- 3 Inertial units and one GPS, which is good"There are two GPS systems. I thought it used both... although I'm not sure if there is a priority system for the Left/Right GPS and I don't know what happens if there is a discrepancy between the two (All radio aids are compared with the IRS position, so I guess the bad one will be rejected if it is too far out of tolerance).Using raw DATA on the ND, the GPS symbols can separate if they compute different positions, but if they get pretty close to each other, the two symbols become one to reduce clutter.Cheers.Q>

Share this post


Link to post
Share on other sites

Well Mark as you said "it is an Airbus tech document..." and they have a different bent on aviation. In fairness they may have been reffering to turning the FD bars off on a visual approach. This is the only time in a jet where you would perhaps turn them off as the FD may not be commanding what you want. If you were visual off an ILS then you wouldn't turn the FD's off. Why would you? It is still giving valid GS information usually right to touchdown or at least until useable PAPI / VASIS information was avail. A non-precision approach on the other hand you could switch off the FD's, when visual, as the descent path info may be invalid although even that ideology is changing. Most jet aircraft non-precision approaches are flown in a similar style to an ILS approach (approx a 3 degree GS) and use purpose built approaches in the FMC data base. This allows the approach to be flown in VNAV with a poor mans GS (the VNAV deviation indicator). Personally I always leave the FD in even on a visual approach or off a non precision approach. If I am visual and visually showing on slope (and no other GS info avail)then I get the PM (pilot monitoring) to dial in half the groundspeed x 10. So if I am 160 kts on the slope then set 800 fpm down on the VS. This then gives me a reference base to use. If I deviate slightly off slope for some reason then I regain it and nail the FD command (as well as cross checking attitude) and fine tune the VS setting if need be. It also provides a visual clue that you are deviating off what should be a constant rate of descent. This is useful especially when flying at night into isolated aerodromes where the "black hole effect can be a real problem. Take Rarotonga on a sh***y night. Why on earth would you want to turn off the FD's? Any vertical profile guidance should be used and to me this would imply leaving the FDs engaged. CheersSteve

Share this post


Link to post
Share on other sites

Interesting insight Steve, thanks!Personally the airbus documentation seemed to me to be odd advice, though I'm sure the airbus philosophy would differ for a good reason. For me it has always been a case of keeping the FD on as I fly my visual approaches with reference to the ILS wherever possible. Good to know I'm on the right track.Lately I've been flying more visual approaches w/o an ILS but when I do I simply leave the FD on and make a point of not relying on the bars for guidance.

Share this post


Link to post
Share on other sites

Simply from a lay simmers prespective, I rarely use the FD command bars. My observation is that they only communicate information that I have available more directly available elsewhere. It is second hand information. If I need the news, I want to observe it directly, if it is at all possible. Generally, it is. For initial climb guidance, I focus on the airspeed tape for vertical guidance. I'm flying airspeed and monitoring deck angle. Just keeping it on speed and off the rake. If anything, the speed bug is my flight director.If I set the MCP to V2+10, the speed bug will stay put (or move to my current, faster airspeed) at Vnav capture. If something goes wrong and pitch swaps to FLCH, the bug will hop up. It's all right there in the speed tape. I never even look at the command bar. It's old news. For approach, I'm really beginning to like the ND in App mode. I tried a 50 knot cross wind approach into LAX last night. Boy does that look wierd in the ND. But I could see the airplane deviating from the LOC's 'track' before the LOC bug (or the FD command bar) budged. Using the ND in APP mode seems to provide me an early warning system for LOC course track deviations. For vertical guidance on approach, I use the GS scale as 'course tune' for glidepath, and VS to 'fine tune' my glidepath. Again, the FD command bars are just too late to pick up a 100 FPM deviation from the rate that will keep me on the slope. Once again, the FD is late, old information.However, I would not turn off the FD. Why would I? I want as many redundancies available as the airplane will provide. But to me, the FD is becoming less and less a primary, 'first look' source.What cha think?

Share this post


Link to post
Share on other sites

>Actually after an autoland you can turn the FD's on and off>until your hearts content but you will stay on the centreline>until you either overide or disconnect the Autopilot.>You can disconnect the AP and fly manually but the FD will>still give commands to fly the ILS if that is the approach you>where flying.>The FD and AP systems are independant but both are controlled>via the MCP. For example if you which to sidestep from one ILS>to another you need to switch off both FD's and disconnect the>AP in order to do so.>Cheers>SteveThat's what I was thinking. The pilot can disconnect the A/P and the FD will give you the commands to fly the approach manually. Ken.

Share this post


Link to post
Share on other sites

For vertical guidance on approach, I use the GS scale as 'course tune' for glidepath, and VS to 'fine tune' my glidepath. Again, the FD command bars are just too late to pick up a 100 FPM deviation from the rate that will keep me on the slope. Once again, the FD is late, old information.Hi Sam,I use the glide slope scale as a guide to being on the correct glide path. I see what you're saying about the FD command bars. The vertical speed can diviate by a 100 fpm but by the time the command bars have moved, I'm already either slightly above or below the glide path. When I disconnect the A/P about a quarter mile from the runway, I try to hold the same pitch with the yoke but it still diviates slightly. I believe this is due to the joystick having a much smaller distance to travel than the yoke in the real thing. I'll try the LOC mode on the ND and see how I come out. Ken.

Share this post


Link to post
Share on other sites

It is good airmanship to take your cues from more than one source. The PMDG FD's are slower than the RW FD's by my observation (but not by too much). One of the tricks of using a FD is to "look thru" it. It really depends on just what the FD is commanding as to how accurate it will be. It can be cumbersome for gross deviations but if you follow it exactly it will maintain a condition well. That means that the cross hairs must be within the small box. As for the ILS or LOC approach I use the FD's and the ND on the smallest scale. Once on the LOC all you have to do is maintain the inbd ILS course on the TRK display at the top of the ND. If the trk is the same as the inbd crse then you must remain on track. There is no need to figure out what drift effect the wind is causing.As for deviating at the end of the ILS approach you will find that this is more likely due to ground effect becoming prevalent. This seems fairly accurately modelled possible a little on the agressive side.Make sure that the PFD and ND are enlarged to help making the display more readable and therefore the flying more accurate. CheersSteve

Share this post


Link to post
Share on other sites

>It is good airmanship to take your cues from more than one>source. The PMDG FD's are slower than the RW FD's by my>observation (but not by too much). One of the tricks of using>a FD is to "look thru" it. It really depends on just what the>FD is commanding as to how accurate it will be. It can be>cumbersome for gross deviations but if you follow it exactly>it will maintain a condition well. That means that the cross>hairs must be within the small box. >As for the ILS or LOC approach I use the FD's and the ND on>the smallest scale. Once on the LOC all you have to do is>maintain the inbd ILS course on the TRK display at the top of>the ND. If the trk is the same as the inbd crse then you must>remain on track. There is no need to figure out what drift>effect the wind is causing.>As for deviating at the end of the ILS approach you will find>that this is more likely due to ground effect becoming>prevalent. This seems fairly accurately modelled possible a>little on the agressive side.>Make sure that the PFD and ND are enlarged to help making the>display more readable and therefore the flying more accurate.>>Cheers>SteveThanks Steve. But I have one interesting thought. I noticed on certain occassions in FS when I come over the threshold, my PFD says I'm about 1.8 or close to 2 nautical miles from the runway. If I remember correcly, the localizer is placed at the other end of the runway. But the glide slope transimitter is placed about 1000 feet from the end of the landing runway. Is the distance given on the PFD reference to the glide slope transmitter placed at 1000 feet from landing runway threshold or is it referenced to the localizer placed at the other end of the runway?Ken.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this