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Dual FMC failure Boeing 737 ng

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Dual FMC failure Boeing 737 ng

Old 10th Apr 2011, 13:31
  #21 (permalink)  
 
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A VOR fix jutted in a map on your lap, a line taken with a ruler to the next point. At track line obtained between said points...

So what is your accuracy in setting such a point? Are you sure you get radial 034 from the VOR or 037, the rose around the VOR on an enroute chart is pretty small. Are you going to actually draw on the map at all? Next from the inaccurate found point, perhaps just identified by holding a finger on the map, you are now going to draw(?) a line to the cleared point. How precise are you going to obtain that track in degrees (measured from the angle from the nearest median)?

(Don't say that you will obtain it from the flight plan, since of course you are aware that at most handoffs to a new sector you get a direct to the next sector boundary.)

So now you arrive near the next point, and of course one of the criteria are met first, because no way you will be bang on with the above approximation. When will you initiate the turn to the new track? How will you correct that track to get you back on precise route again.

Next you'll see that over the next points there will be an airway change. There is only 15nm between the next to points, unfortunately the controller doesn't provide you a direct too 200nm away. You are still to pround to ask ATC for radar vector and while you are looking the the map to find a new suitable VOR to tune, identify, jut a new unprecise point in your map, find a new unprecise track in the map (because you didn't turn over the required RNAV point you still can't use the flightplan).... all while moving at 8 nm pr. min.

While sitting heads down, ATC advice you to immediately turn right due to converging traffic in your 11 o'clock position. They then require to know why you strayed off your assigned route and inform you that they have to write a report.

Which part of unprecise don't you understand?

All may work well over Northern Australia, but over Europe?

What part of "The phrase "Negative RNAV" is appended to each radio message on initial contact with each ATC frequency change." do you or ATC not understand?
Exactly! Only makes all your assumptions more hypothetical. When you say negative RNAV, ATC will send you off on a vector straight away - because they want to drink their coffee peacefully without "Omegaman" straying of his route and messing up their planned strategy.

Are you going to decline the vector and say.. negative RNAV but we are able direct RNAV point XYZ anyway??
Even more so when the vector given significantly shortens your route?
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Old 10th Apr 2011, 15:02
  #22 (permalink)  
 
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The FMC is tracking the aircraft in NAV direct to your "direct to" tracking point. It fails, and you select HDG on the MCP, so you are still on track, tracking direct to the point. You call ATC and inform them you are no longer RNP capable due equipment failure.

If it was me:
ATC ask "Do you require vectors?", they get a cheery "No thanks."
ATC ask "Do you require routing via VORs?", they get a cheery "No thanks."

If they want to provide vectors to meet their operational requirements, due to traffic separation with a non-RNP aircraft in their sector, then of course that's fine.

Knowing I am on track, a quick VOR check just confirms the expected time over the next point ("confirms", as the PLOG is filled out, of course), and navigation continues as outlined above.

I would actually enjoy the diversion from the boring old normal, and have a pleasant time with a minor failure which can be easily dealt with entirely "in cockpit".

If it was you:
Apparently feeling unable to navigate your aircraft, you require Vectors - so a PAN call would be appropriate, to guarantee the extra handling and workload from ATC.

If it was Jinkster:
A MAYDAY call is appropriate, as he apparently feels that an FMC failure with him as pilot will result in "the aircraft laying in flames" if he doesn't get outside help.

In terms of navigating with a map. Yes, I carry a Jeppesen plotter (specifically designed to be used in cockpit with Jeppesen charts) and a Jeppesen CR-2 circular slide rule. The method for using a ruler and pencil and whatnot to navigate about the place is beyond this discussion (i.e. - as a (presumably) licensed pilot, you shouldn't have to ask !)
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Old 10th Apr 2011, 20:36
  #23 (permalink)  
 
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treat it like a -200. What's the big deal? Has everyone forgotten how to fly and navigate? Not every a/c in the sky is an EFIS a/c. "don't panic, don't panic" comes to mind, as does KISS.
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Old 10th Apr 2011, 21:01
  #24 (permalink)  
 
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Originally Posted by RAT 5
treat it like a -200. What's the big deal? Has everyone forgotten how to fly and navigate? Not every a/c in the sky is an EFIS a/c. "don't panic, don't panic" comes to mind, as does KISS.
I'm glad I'm not the only person who was thinking that!
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Old 11th Apr 2011, 05:55
  #25 (permalink)  
 
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In terms of navigating with a map. Yes, I carry a Jeppesen plotter (specifically designed to be used in cockpit with Jeppesen charts) and a Jeppesen CR-2 circular slide rule. The method for using a ruler and pencil and whatnot to navigate about the place is beyond this discussion (i.e. - as a (presumably) licensed pilot, you shouldn't have to ask !)
Is that a CAA rule in the UK to carry such items?

If it was me:
ATC ask "Do you require vectors?", they get a cheery "No thanks."
ATC ask "Do you require routing via VORs?", they get a cheery "No thanks."
If it were me, i would say YES please and go on with my coffee
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Old 11th Apr 2011, 06:14
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I love this discussion between those who can navigate using first principles and those presumably brought up on the modern nav. systems! I remember the days when all pilots navigated in the way described by checkboard. It worked fine and many ATC units around the world had no radar and couldn't have helped even if asked.....apart from the odd QDM!
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Old 11th Apr 2011, 06:46
  #27 (permalink)  
 
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what should be the course of action in case of Dual FMC failure in Boeing 737 ng
No one has stated to blindingly soddin obvious....

Cycle the FMC CB's and keep your fingers crossed.

Dual FMC fail is a known issue. A Static Ram Fault in the failing FMC can flood the intersystem bus with garbled data. This causes the offside FMC to fall over when the data handler gets overloaded.

"All things being equal, the simplest solution tends to be the right one"
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Old 11th Apr 2011, 06:53
  #28 (permalink)  
 
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Dual FMC Failure......

Errrrrr.............. Handing over............

Not a biggy, used to happen not too infrequently on the classics. Re-plan via navaids advising ATC of amended route.
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Old 11th Apr 2011, 07:52
  #29 (permalink)  
 
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If it were me, i would say YES please and go on with my coffee
And what would you do over the Atlantic/Pacific/Africa/Australia/NE Asia? (i.e. No radar available - even if you need it.)
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Old 11th Apr 2011, 22:16
  #30 (permalink)  
 
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First of all, the IDU shows True Track. You seem to have forgotten that, so that will send you straight off course with whatever magnetic variation in the area you are flying. Knowing your equipment may be a good starting point.

Assuming that you did read the instructions, let's be generous and say that because you manage to make some half precise fixes with your pencil along the way you only make a 3 degs error over e.g. a 300nm direct-to RNAV point. With basic MDR rules that would equate to 15nm. Considering the requirement for B-RNAV routes is 5 nm accuracy, I am sure ATC will be very happy about that.

You even mentioned yourself in your first post that the MEL says not to operate on BRNAV routes, but for some reason you decided to disregard it to go your own ways, because you know better and like to have fun!

Who said anything about panic or pan-pan, that would both be pretty ridiculous. It's hardly a state of urgency to request direct to a VOR (may I suggest brushing up on this subject as well). Like Greenslope this was exactly what I did and it was declined by ATC who instead provided a vector. Their choice not mine, their convenience, I don't care.
But I am not going to use my resources on ridiculous and unnecessary DR navigation and risking that my mistakes (of course some are infallible and never makes mistakes ) become someone else’s problem.

While you are sitting heads down drawing in your map, straying off your assigned route, I will calmly be drinking coffee like de facto ...or maybe even fly the aircraft or checking the odd volmet.

And what would you do over the Atlantic/Pacific/Africa/Australia/NE Asia? (i.e. No radar available - even if you need it.)
This was for my part covered before. I wrote that in the airspace above Europe DR navigation is not appropriate. With a failed RNAV system above the Atlantic it is on the other hand highly appropriate. Whatever resulting deviation must be made good when navigational aids are available again.

That you fail to see the difference shows lack of airmanship.

To Helen49 - SLF, I presume:
"The superior pilot uses his superior judgment to avoid having to use his superior skills". The macho "I'll show the world how good I am" pilot is luckily (almost) a thing of the past.
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Old 11th Apr 2011, 23:29
  #31 (permalink)  
 
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Any stories of dark cockpits halfway to Hawaii?
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Old 4th Sep 2011, 23:55
  #32 (permalink)  
 
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Interseting conversation.
My first four years airline flying were done with no area nav capability or autopilot and I feel pretty comfortable that I could get by ok going back to basics if I was without my dual gps, irs , fmc combo, and one of the first mental calculations i do upon reaching the cruise is my kg's per nm and my nm per minute for todays conditions, but.........my first priority is providing the safest travel to destination for my passengers. In this situation utilizing the capabilities of ATC and keeping the workload of myself and my copilot as close to normal as possible would achieve this. If for reasons of fun/ego etc I decided to do revert to old practices when it was not the only option, I would be
a) creating more workload than was required of the situation
b) increasing the chances of missing something normal (a checklist or wx change or atc clearance or transition altitude etc etc)
c)reducing my situational awareness by diverting my brain cells into calcs rather than leaving them free to observe how the flight was progressing.
d) creating a 'non-normal' situation and in non normal situations errors are much more likely to occur (lets face it, navigating like this is, now days, not a normal situation)
In addition to these things, my first officer may be more rusty than me or completely incompetant in this type of navigation (thats the world we operate in,I'm not saying it's right) and so I am effectively making it single pilot as well, taking him/her out of the loop, reducing the chances of effective cross checking.
I have no doubt that I could do it safely, but it wouldn't be the safest option, and unless there are significant costs to the safest option, I'm going to take it. If I want to practice that sort of navigation there is nothing stoping me from doing so when the fmc's are working fine, that way, one day when it is the only option available to me I will be proficient, but to do it when other options are available in order to have fun or stroke my ego is , in my mind, irresponsible.
Just my 2 cents.
Framer
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Old 13th Jan 2014, 04:46
  #33 (permalink)  
 
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737-900 dual fmc reboot after acars wind request

hello,


I have fmc reboot after acars wind request, after that LNAV was lost and cannot re enter cost index, anybody had this problem?,
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Old 22nd Apr 2016, 19:00
  #34 (permalink)  
 
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Old topic kicked up...

In case you have a double FMC failure when crossing the Atlantic, on a 737 NG with no CPDLC etc., and your flight plan data is something as:

5130N average true track 073
5220N average true track 081

And your FMC's fail at 25W. Which course do you fly?

Apparently, it's 083 true. I just don't know the correct procedure to get to that.
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