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History And Opinions On The FMC

Thu Mar 22, 2007 12:02 am

Hi all
I am doing coursework for school as i am in Year 11 (UK system) and i am sitting my GCSE's next year. For my IT Coursework, i need to investigate how ICT has changed an industry, and being an aviation enthusiast, i choose to do the Flight Management Computer. Does anybody have opinions on the FMC? Is it better than traditional navigation methods? Also, does anybody have any history on the FMC, e.g. First aircraft to use it and in what year?
Any help will be much appreciated.
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RE: History And Opinions On The FMC

Thu Mar 22, 2007 12:26 am

Quoting A320ajm (Thread starter):
Does anybody have opinions on the FMC?

Do you mean the love/hate relationship we (pilots) all have with it? Big grin It has simplified life enormously for us by having the database of all navaids and waypoints stored onboard. It has enabled us to fly much more complex arrivals and departures than before, and now with GPS added in, they're flown much more accurately too. We get far better performance data (time over waypoints, fuel used, expected fuel at destination etc.) than we did before, and freed up our time to concentrate on other things, like making sure we're going where we're supposed to go. From a safety standpoint having the FMC programmed with things like crossing restrictions (speed and altitude) means there are far fewer mistakes made in ensuring the plane is where it's supposed to be.

Some pilots don't like the fact that we do more 'monitoring' than 'flying' now, but I think the entire industry is safer for it. We see it all the time in the simulator - if someone is so involved with keeping the airplane right-side-up, especially during an emergency, they have little brainpower left to help the other pilot deal with the situation. As with all technical aspects of flying however, there are a few pilots who just don't like working with the FMC, and try doing things the old fashioned way. In most modern airplanes however, the FMC is so deeply integrated into the aircraft systems that it must be used for the airplane to operate at all. A few older aircraft that had the FMC installed later (or with minimal interaction with the autopilot or other systems, such as the DC-10) allowed the pilot the choice of following the FMC info or doing it on their own. Most of those planes have been retired though, and everyone now pretty much has to use it, if it is installed. For the most part though, it's a very useful tool. I've flown both Boeing and Airbus aircraft, and despite some of the programming differences between the two, they both end up doing about the same thing for us - ensuring that we are going where we want to go, and letting us know how we're doing along the way.

I honestly don't know the history of the FMC. They first came out when I was still in high school (or maybe even earlier), so I'm afraid I can't help you there. I have flown transport category planes without an FMC (Saab 340), but we were still low and slow enough that we could get around using basic VOR navigation and keeping track of our fuel use on the flightplan. With longer flights and faster aircraft, I can see where someone like the flight engineer or navigator (in the old days) would be kept very busy doing the sort of things we take for granted with the FMC today.

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RE: History And Opinions On The FMC

Thu Mar 22, 2007 10:07 am

Honeywell developed the first FMC in the late 1970s.

The first Boeing to have an FMC was the 767-200 (in service Sept 1982). The first Airbus with an FMC (the A310) went into service in 1983. I suppose there may have been bizjets with earlier systems?

Before the FMC there were performance computers like the PDCS and PMS which optimised vertical profiles to increase fuel efficiency (what we would call VNAV these days). The FMC combined this function with lateral navigation (previously provided by the INS system).
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RE: History And Opinions On The FMC

Thu Mar 22, 2007 10:24 am

The first transport jet with an FMC, which included LNAV/VNAV and full time performance engine management functions was the L1011, first installed on the L1011's of SaudiArabian Airlines, circa 1978
This installation also included a 12 inch moving map display which worked very well indeed.
The unit was manufactured by Hamilton Sunstrand, if I recall correctly.
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RE: History And Opinions On The FMC

Thu Mar 22, 2007 11:18 am

The B737 FMC
Wiki link
Couple of good links.
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RE: History And Opinions On The FMC

Thu Mar 22, 2007 11:27 pm

From the first time I heard of an FMC and saw the operation during flight from the jumpseat I thought, WOW, what abilities this will provide pilot/controllers. I then learned more of the differences as time went along, how some boxes are able to do more than others, how some cycle waypoints different than others.

I understanding that each manufacturing company (Smiths, Honeywell, Universal, etc.), have their own particulars, but all manufacturers in my little mind should be required to build to one standard for certification with hardware and software minimum operational requirements that provides a level of continuity for things such as a runway transition in conjunction with a STAR, the coding of leg types from on a SID/STAR, and as mentioned earlier the cycling of waypoints to where all boxes fly a procedure the same thus removing all doubt in a controllers mind.

Some of the issues I mention above are being worked on but it shouldn't take some 25 yrs to get stuff to a common standard.
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RE: History And Opinions On The FMC

Fri Mar 23, 2007 6:47 am

FMCs or FMS' are wonderful pieces of software, in fact, my Master's research will be based on it! I think it is a wonderful addition to the aircraft's cockpit, but it also has its negatives.
Here are some of the positives - much easier for the pilot to navigate from one place to another. In the olden days (not too old), you would have to use the INS to navigate, essentially punch in waypoints, etc and the flight engineer would have to make all sorts of fuel calculations and such. With the FMC, everything is done automatically for you.
Another positive is its flexibility - if for example, there is an inflight emergency and you have to divert to the nearest suitable airport, you can just plug it into the FMS and it will automatically recompute the route, fuel burn, time of arrival etc.
Ability to store frequently traveled routes - the pilots don't have to manually enter in the waypoints, they can just choose the route stored in the database and modify it if need be.
Easier to follow ATC constraints - During arrival or departure you can manually insert restrictions as mentioned above. Much safer as well.
With regards to navigation, almost all FMS use GPS for navigation now a days. VOR, DME and NDB are also used, but accuracy wise, GPS beats almost everything hands down. Traditional navigation would involve the INS as I mentioned above, but the INS needs to be recalibrated numerous times in order to maintain its accuracy. A good example of the propagation of INS errors may be the KAL007 incident which 'could' have been caused by inaccuracies in the INS.
The FMS also knows how the aircraft wants to fly. This relates to my area of research which involves CDA (Continuous Descent Approaches); the aircraft flies an arrival without any restrictions whatsoever, the main point is the engines are at idle during the entire descent, no level segments unless needed.
Negatives for the FMS: Its not so easy to change an arrival runway! For example, if SoCal TRACON clears you to 25L but for some reason, you have to change to 24L, its requires some amount of keystrokes to change waypoints etc. Could get annoying.
FMS is very very complex! It takes ages to debug and sort through the logic!

Something else to add: ACARS! The FMC also has the ability to use ACARS which is used to send all sorts of data such as aircraft weight, fuel, wind, time of arrival etc to ground stations.

Hope this helps!


[Edited 2007-03-22 23:54:36]

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