unreliable FMS on E-145?

[FinalVectors]

Hi!

I am a ATCO from Norway, working APP into ENGM.

Is there anyone here who have and knowledge of E-145?

I have many times experienced suddenly turns (mostly right turns by 15-20 degrees) by E-145 when they on own navigation.
Sofar it havent made any problems because when traffic is "thight" they mostly on a vector and not own naviagtion.

Pilots allways say its a FMS problem. Can anyone explain me why this happens?
..maybe it's just because they have a brasilian computer ;)

fly safe!

finalvectors

[Busdrvr]

Which FMS system do you operate? I flew the 135 and 145 for a couple of years, equipped with the dual Universal system, and never experienced a problem like you describe.

[JJflyer]

FMS is as good as the info it is given. Very simple: C.rap in, C.rap out.

Most of the "What's it doing now" occurances seem to come out of either the pilots not fully understanding the philosophy or the operation of their FMS system or enetering faulty information into the unit (Wrong co-ordinates) or NAV database being out of date/faulty. One possibility is that when cleared direct to a fix, pilot selects the wrong one of available ones in the catalouge and aircraft ends up steering toward the one 4800 miles away rather than to the fix 46 miles away.

Some FMS systems are not very userfriendly. I have used many of the Universal UNS systems and find them quite OK, but less friendly than the Honeywell/Smith commercial systems on seen on many Boeings.

JJ

[metroman.nl]

Hi,

I'm flying the 145 now for 4 years and 15 to 20 degrees sounds a bit much for me, and we have both honeywell and universal.

However small deviations can be noted 1 to 2 degrees (initial bank left/right) when coupeling to the FMS from HDG or any othert lateral mode right after selecting a Direct-To. If you wait about 5 seconds before selecting FMS (LNAV) this does not occur, it has to do something with datatransfer rate FMS to the autopilot computer (or something to that effect, e.g. it takes also about 5 sec to display on the EFIS)

Other than that sounds like JJFlyers comment C.rap in gets you C.rap out.... (a hint would be if this always happens in the same spot ;) )

Greetz

[FinalVectors]

Hi! And thanks for the answers;)

I seen this problem with unaccurate naviagion and sudden turns with E-145 many times. Ofcourse it only happens when ACFT is on own navigations. Vector still works fine;)

I have only seen this with E-145 from BRT..and BRT flyers here who can put some more light to this?

As I wrote before it havent made any problems for separation yet, because if things will be thight ACFT will normally be on heading. But this can be one of all the things which can lead to an incident, so dont like this suprise so much.

But me and most of my collegues use little more space when we have E-145 flying because of this "snag". What I wrote about in the top of this thread is probably the biggest turn I seen sofar. The pilots flying was little suprised by it too I think:D

Thanks again for the answer.

Final vectors
ENGM APP

[West Coast]

Just a swag based on something I've seen in the US, perhaps unique to our system.

ATC will clear an aircraft direct to the destination airport. The airport may also have a NAVAID of the same name not located on the airport. You receive direct to XYZ and interpret that as the airport and not the NAVAID which is what the controller had in mind and happens to be miles away from the airport. I understand there is an ongoing FAA effort to rename NAVAIDs that share the same name as the airport, a few years back the Salt Lake City VOR was renamed Wasatch because of the confusion.
Perhaps this might be a possible source of the problem, especially if it happens to the same carrier and on the same leg.

Edit: just read you mentioned it happened mostly on vectors, so above may not cover it. It may be an AHRS problem perhaps, in manual instead of mag. Does it happen shortly after takeoff, after initial turn or two?

[Staple]

Spoke to someone who flies them yesterday.....

Seems that the Universal FMS fit is fine but the Honeywell system, even after pausing as suggested above, often initially turns the wrong way with a direct to and doesn't cope well with turns on SIDs just after departure.