Dual FMC failure Boeing 737 ng
what should be the course of action in case of Dual FMC failure in Boeing 737 ng ?
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Dust off the PLOG and QRP.
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Use IRS for Lat-Long. Plot it on the Jepp say every 10 minutes or so. Since you would still have a Track Line available, you can use the ND to navigate using the following method:
*Set the Track Required in the MCP Course Window. *Set the ND to CTR VOR mode. *In the ND you will have the hollow Course needle and the white track line. The course needle is your Track Required[TR]. The Track line is your Track Made Good [TMG]. Use HDG SEL to turn the aircraft to keep the TMG line inside the TR line. *This way you will be able to give wind corrections, make airway course changes etc with a bit of ease. Hope this helps:) |
Or if you are within range of a VOR you could just use VORLOC and ALT HLD and resume conventional NAV
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No FMC, no RNAV capability. Therefore not approved to use european airspace flying IFR except with special permission by every concerned ATC unit. So inform ATC and ask for vectors to the next airport.
Judging from our OFPs (LIDO) it isn't required anymore to have all waypoints or even all airways on it and therefore is not usable for navigation. Actually had a case of FMCs being unable to "talk" to the rest of the airplane which resulted in autothrust always trying to achieve 104% N1 regardless of actual speed and MCP selected speed. If the same is true with completely failed FMCs you probably have basic autoflight modes, but no autothrust anymore which shouldn't be a problem though for any halfway competent pilot. |
All perfomance related calculations must also be conventionally done, like TOC (if relevant), TOD, actual weights and respective speeds.
Regarding this topic I recently had an FMS unable to give any performance outputs on a 737 classic: not a too big deal, but workload, especially on really short sectors, might slightly increase. p.s. my first post (tech-log, I am pretty brave!) but a long-time reader. Hello everybody :O |
what should be the course of action in case of Dual FMC failure in Boeing 737 ng ? 1 Resume conventional navigation. Without an operating FMC, LNAV and VNAV are not available. 2 When preparing for approach: Use the manual N1 set knobs to set the N1 bugs. ---- I had the pleasure of this a few weeks ago. With a "dual" FMC failure in a classic. Well... actually there is only one FMC in most classics, but the result is the same as a dual fail in an NG = "FMC FAIL" written on both CDUs and loss of map mode on both sides. ATC was informed and we got vectors for the remaining 1 1/2 hour flight, since our route was mostly RNAV points. The checklist was read and approach speed and go-around N1 was looked up in the QRH. Flight progress was checked by looking in the Jeppesen charts and finding appropriate VORs where our flight plan points could be located with a radial and DME distance, so that we would have an idea when passing abeam them. During descend it started working again with the message "select active waypoint" which is normally assosiated with a power loss - probably condensation somewhere in the wiring I would guess - it was bloody cold that night. We didn't have endless amounts of fuel so without the FMC prediction for fuel at destination, it was a bit uneasy feeling until we got a system going with VORs for cross checking our position. Otherwise it's no big deal. |
Yeah, don't bother with the peanut gyro, VOR, DME, and ADF. It's over.
Once you can't see your little airplane on the screen moving around, toast. |
Its no biggie other than that you are stuck with conventional navigation and manual performance calculations, as previously mentioned ;) Happened during my last sim ride (both boxes went blank, Map display blanked), interestingly enough without intent from the examiner - turned out that the sim became desynchronized, we continued flying nonetheless, became an interesting lesson after all...
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Standard fit in an NG is the same as the -300: Two Control and Display Units (CDUs) feeding ONE Flight Management Computer (FMC), however dual FMCs are an option, as are Alternate Navigation Control and Display Units (ANCDUs)
ANCDUs are a CDU with the addition of a basic area navigation (i.e. LNAV, but no VNAV) computer installed. You will know if you have this option as you will have and Alternate Navigation Switch (ANS, with positions L and R) on the glareshield to direct the correct nav inputs to the autopilot. If you don't have ANCDU backup: Take-Off & Climb
Cruise
Descent - Approach
N.B. : experience shows that FMC failures are usually of relatively short duration, if operating in ANCDU with IRS pages displayed on the CDU there will be no indication of FMC reset. Press any of the top two rows of keys on the CDU (INIT/REF, RTE, CLB etc) to test FMC status |
Navigate Raw data (or radar vectors if you have no shame about not being competent enough to fly an aircraft ;) ) Please do tell me how to fly direct to RNAV point "NOVOR" raw data? := Of course you can request direct to Im-da-man VOR, but if the airspace is complex enough, you find that ATC will prefer to keep you approximately on the filed RNAV route with vectors that you don't interfere with other airways. Have a look at your enroute charts for eastern-europe and you will find that most airways practically contains zero VORs or ADFs. Calculate your descent point from the chart M0.74/250 KTS DESCENT SPEED (ALL ENGINES) (PI 11.5) |
Please do tell me how to fly direct to RNAV point "NOVOR" raw data?:= It's called navigation - you have a working clock, a working heading reference, you can plot a fix to determine your current position ... ;) In your particular case - the dual IRS's in the 737 were still working, all you had to do was look up :rolleyes: for your actual track & ground speed, and get a chart out to see where the place was. "Children of the Magenta line" indeed - that pilots today even have to ask how to do it, as though it is an impossibility without vectors, shows quite a bit. :uhoh: In Australia, after the Omega navigation system was decommissioned, my airline had us flying with no area navigation system at all in a BAe 146 - just NDBs and VORs. On many of our routes we were completely outside navaid coverage (of any sort) for up to an hour. In one instance I was flying an aircraft with an unserviceable autopilot from Cairns to Darwin and had to divert north around a cyclone in the Gulf of Carpentaria. http://www.aboutaustralia.com/a2it_p...ravel/L46n.jpghttp://i665.photobucket.com/albums/v...rd/cyclone.jpg The solution (diverting left and right around thunder heads, outside navaid coverage of any sort, without autopilot) was simply to get a chart out, and run a series of air plots for each change of heading for an hour, then apply forecast wind vectors to ded-recon to a point back on the airway, and pick up the VOR radial. |
Or nm = height x 3, if you like to keep it simple |
It's called navigation - you have a working clock, a working heading reference, you can plot a fix to determine your current position ... In your particular case - the dual IRS's in the 737 were still working, all you had to do was look up for your actual track & ground speed, and get a chart out to see where the place was. Neither hardly wise choices in congested RVSM/RNAV airspace. :ouch: For data to be "raw", there needs to be data in the first place. That means that you have the ability to track some form of navaid which provide data. Did you even consider the drift of the IRSs??? Such old ladies are not the most precise, and I may remind you that the updating from VOR/DME is applied to the FMC (which just failed). Hence you are left with a position that may have several hours of flight time and thereby drift - perhaps 10 miles or more. So what is the accuracy of your navigation when you include the accuracy of your DR? Sometimes it's good to be cleaver, and sometimes it's better to leave out the completely irrelevant anecdotes (plus insults). |
Cosmo,
I asked you how to proceed to an RNAV point raw data, not by proceeding VFR or Dead reckoning. As for IRS drift, the 737 Clasic is meant to be RNP 12 without updating. In my experience I wouldn't bank on it though! And another exclamation mark for good measure! |
I asked you how to proceed to an RNAV point raw data, not by proceeding VFR or Dead reckoning. So, to spell it out:
The saying is that pilot's earn their larger-than-bus-driver wage not when things are going fine, but when things go wrong. Personally I would be professionally ashamed to ask for ATC help to navigate my aircraft, when no Navigation equipment on the aircraft had failed - just the box that did the navigation thinking. *,(I was going to mention the fix-to-fix thing (although I never called it that) but thought it too complicated. Good link, though.) I would use that approaching the RNAV fix point. |
The saying is that pilot's earn their larger-than-bus-driver wage not when things are going fine, but when things go wrong. Personally I would be professionally ashamed to ask for ATC help to navigate my aircraft, when no Navigation equipment on the aircraft had failed - just the box that did the navigation thinking. Personally I'd get as much help as possible!! :ugh: |
Perhaps given the standard of respondents here, and their level of confidence in their professional piloting abilities, failing to find and maintain a heading, given two IRS's to help, IS too dangerous for them.
To think that Area navigation has only been around in my lifetime ... Mick O'Leary is right - pilots today are only bus drivers, worth £20,000 a year. :( |
You are not answering my question. You are just repeating yourself, with the same dead reckoning bs (and condescending tone). You are advocating to take an unprecise starting point, apply an even more unprecise methode, to find a point that ATC expects you to overfly with great accuracy. Great airmanship!
Personally I would be professionally ashamed to ask for ATC help to navigate my aircraft It's not about being dangerous or difficult, it's about being inappropriate. I would happily fly DR if the FMC fails when no navaids or radar coverage is available - hardly the case over eastern europe. Sciolistes, thanks for the link. Yes probably not very useful when you go 8nm pr. min, and again like DR too much of inaccuracy. And when starting to turn 30 deg off track to find an initial heading ATC it probably going to ask "confirm inbound XYZ". |
You are advocating to take an unprecise starting point apply an even more unprecise methode to find a point that ATC expects you to overfly with great accuracy. |
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