Jump to content
Sign in to follow this  
Guest mdamstel

backup when FMC fails

Recommended Posts

Guest mdamstel

Hi fellow sim pilots,does anyone know what real life pilots use as a backup when their FMC fails?Regards,Mdamstel

Share this post


Link to post

Although is FMC is one of the less likely parts to fail (it's got an identical backup), like any other commercial plane, the 737 is equipped with navigation radios, so you just fly it the old-fashioned way from VOR to VOR.Cheers,Gosta.http://www.hifisim.com/images/as2betateam.jpg

Share this post


Link to post

If its only the FMC Computer the fails (basically the FMC), then you still have the CDU! (The CDU is what is located in the cockpit)You can still fly all the waypoints that are in the legs page, and you can add waypoints by using the lat/long coordinates.Other FMC functions are not available, however.If you meant a complete FMS (FMC+CDU) failure, well, then you can still request radar vectors if you have radar coverage (most parts of the earth) or you'll simply navigate using VOR's and ADF's.basically the way you navigate in a non GPS equipped GA aircraft.Regards,Mark


Mark Foti

Author of aviaworx - https://www.aviaworx.com

logo_avsim.png

Share this post


Link to post

Some operators only choose one FMC for the 737!(You still have two CDU's!)Regards,Mark


Mark Foti

Author of aviaworx - https://www.aviaworx.com

logo_avsim.png

Share this post


Link to post
Guest VCA_CEO

Easy, fly the way REAL MEN did ;-)sorry couldn't resist.Lance

Share this post


Link to post

>If you meant a complete FMS (FMC+CDU) failure, well, then you>can still request radar vectors if you have radar coverage>(most parts of the earth)The CDU is just the display interface for the FMC though - it's my understanding that if you have a dual FMC failure, you're not doing anything with the CDU as well because it's just displaying that data that's being computed by the FMC.Also - most parts of the world are NON-radar environments unless you're talking developed countries like the US, Europe, certain places in South America etc. The 75% of the earth that's covered by water is defintely not covered either... [;)]


Ryan Maziarz
devteam.jpg

For fastest support, please submit a ticket at http://support.precisionmanuals.com

Share this post


Link to post
Guest VCA_CEO

Also - most parts of the world are NON-radar environments unless you're talking developed countries like the US, Europe, certain places in South America etc. The 75% of the earth that's covered by water is defintely not covered either... ;)Then do it like REAL MEN used to! Celestial Navigation ;-)I'm on a roll, LOL ;-)Lance

Share this post


Link to post

Now that's what a lot of people think!Actually, the CDU is given too little credit! It is much more than just a display interface!As I said, you can use a CDU with no FMC at all for navigation (with some limitations though!)!Regards,Mark


Mark Foti

Author of aviaworx - https://www.aviaworx.com

logo_avsim.png

Share this post


Link to post
Guest Andrew Potts

Celestial navigation tricky without the sunroof! Mayve through the eyebrow windows...Real answer to question is... Refer to QRH:- No LNAV and VNAV. Resume conventional navigation.- use the SPD REF selector to set the reference airspeed bugs- use the N1 SET to set N1 bugs

Share this post


Link to post

Hi MarkI would like to know how you can use the CDU without the FMC? As I've understood it the CDU is the interface to the FMC while the MCP is the interface to the A/T and AFDS. Somehow it doesn't make sense... Please enlighten me? ;-)Cheers

Share this post


Link to post

"I would like to know how you can use the CDU without the FMC? As I've understood it the CDU is the interface to the FMC while the MCP is the interface to the A/T and AFDS."Many FMC CDU's have a back up navigation called "ALTN NAV". The CDU is often a standalone mini-navigation computer, but the inputs and outputs (especially on the NG) are very limited. Not being overly familiar with the 737NG, I had to look into the Bulfer manual (p197 in the latest 737NG book). The 737NG ALTN NAV system uses GPS as a reference (other Boeing types may use IRS). It can only compute LNAV data (no VNAV data), there are no outputs to the ND, to the A/T or the A/P.I'd imagine that you would have to fly the aircraft using the MCP HDG selector (but you would have to convert TRU course data (displayed on the CDU) into magnetic course data. A "GPS PROGRESS" page on the CDU will help you figure out if your calculations have been correct.Hope this helps.Cheers.Ian.

Share this post


Link to post

Thanks a ton Ian!Seems the CDU can work as a navigational calculator then, but no interaction between CDU and AFDS. Is this correct?PS. Does anyone have a schematic on how all the different components are interlinked in the FMS?Cheers,

Share this post


Link to post

"Seems the CDU can work as a navigational calculator then, but no interaction between CDU and AFDS. Is this correct?"Correct(in this particular mode)."Does anyone have a schematic on how all the different components are interlinked in the FMS?"Have you seen the one in the Bulfer Manual? It seems to be quite good (BTW, I thought you were going to buy it, Mats?) None of the ones in the Boeing Maintenance Manuals are particularly enlightening.... or comprehensive.Cheers.Ian.

Share this post


Link to post

Hi Ian!>Have you seen the one in the Bulfer Manual? It seems to be quite >good (BTW, I thought you were going to buy it, Mats?) None of the o>ones in the Boeing Maintenance Manuals are particularly >enlightening.... or comprehensiveI did buy the Bulfer Guide and the Cockpit Companion when I started to learn how the DF734 worked a couple of years ago! But I don't remember seeing a schematic in the Guide. Maybe it's in the updated version? Have to give Bill a shout about that I guess. Will look again! Thanks for the heads up! ;-)

Share this post


Link to post

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  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...