Strange CDU Message on 737NG?!
Thread Starter
Joined: Sep 2009
Posts: 3
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From: IN THE AIR
Strange CDU Message on 737NG?!
hi everyone,
yesterday while we are cruising at FL410 strange cdu message appears on CDU which says "ICAO APPR MIS-COMPARE". I clear the scratchpad and checked the system there was no failure or something. I have checked the FCOMs, cockpit companion and mrg but couldnt find anything? do you have any idea?
FlySafe!
yesterday while we are cruising at FL410 strange cdu message appears on CDU which says "ICAO APPR MIS-COMPARE". I clear the scratchpad and checked the system there was no failure or something. I have checked the FCOMs, cockpit companion and mrg but couldnt find anything? do you have any idea?
FlySafe!
Joined: Nov 2006
Posts: 219
Likes: 0
From: the OFCR......and probably somewhere over China zzzzzzzz
If the Airframe is certified for GNSS Approaches it could be a RAIM error or similar.
Only active in dual-
GPS/WAAS installation
with neither GPS/WAAS in
failure condition. Indicates
that position, track or
groundspeed difference
between GPS/WAAS units
is beyond limits. Limits are
as follows:
Position:
Enroute Mode 4NM
Terminal Mode 2NM
Departure Mode .6NM
IFR Approach
Mode .6NM
VFR Approach
Mode .6NM
Track:
If groundspeed is
greater than 30 kts,
miscompare if
difference is more than
4°.
Groundspeed:
Only active in dual-
GPS/WAAS installation
with neither GPS/WAAS in
failure condition. Indicates
that position, track or
groundspeed difference
between GPS/WAAS units
is beyond limits. Limits are
as follows:
Position:
Enroute Mode 4NM
Terminal Mode 2NM
Departure Mode .6NM
IFR Approach
Mode .6NM
VFR Approach
Mode .6NM
Track:
If groundspeed is
greater than 30 kts,
miscompare if
difference is more than
4°.
Groundspeed:
10 kts.
just a thought.
Joined: Nov 2003
Posts: 496
Likes: 12
From: UK
FDB,
I have not seen or heard of this message but in the absence of a definitive answer let us try and work it out. First we need more info, can you tell us the following?
1. What series of 737 was it and approx age?
2. What FMC update was it?
3. Do you have the IAN / GLS option enabled?
4. What airport, arrival & approach was in the FMC?
5. What freq was selected in Nav 1 & 2?
6. Where were you overflying at the time of the message?
7. Have you or your colleagues seen this message before, if so what were the circumstances & what was the fix?
BTW, if this message is not documented in your company FCOMs then you should inform your Fleet/Tech Captain who will see that it is or issue some guidance.
S&L
I have not seen or heard of this message but in the absence of a definitive answer let us try and work it out. First we need more info, can you tell us the following?
1. What series of 737 was it and approx age?
2. What FMC update was it?
3. Do you have the IAN / GLS option enabled?
4. What airport, arrival & approach was in the FMC?
5. What freq was selected in Nav 1 & 2?
6. Where were you overflying at the time of the message?
7. Have you or your colleagues seen this message before, if so what were the circumstances & what was the fix?
BTW, if this message is not documented in your company FCOMs then you should inform your Fleet/Tech Captain who will see that it is or issue some guidance.
S&L
Joined: Apr 2008
Posts: 487
Likes: 1
From: over there
please note i do not fly a FMC equipped aircraft, but from that it almost sounds like an approach that you loaded into the FMC/CDU had an incorrect "name" as opposed to the ICAO name, if you follow me
