[B744] LNAV fly wrong direction?
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Join Date: Jan 2006
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[B744] LNAV fly wrong direction?
Hello folks,
please look at this photo:
http://www.airliners.net/open.file/0866495/L/
The next waypoint on the ND is N19, but the aircraft fly direct to TTF3 (in LNAV mode, indication on the MCP and FMA). But TTF3 is not the acitve waypoint, normally LNAV must turn around 180° turn to N19. You can also see the distance to TTF3 is never 78NM.
LNAV flies obviously the wrong direction - or?! No holding is active, CMD C is active, LNAV and VNAV?
Any comments...
please look at this photo:
http://www.airliners.net/open.file/0866495/L/
The next waypoint on the ND is N19, but the aircraft fly direct to TTF3 (in LNAV mode, indication on the MCP and FMA). But TTF3 is not the acitve waypoint, normally LNAV must turn around 180° turn to N19. You can also see the distance to TTF3 is never 78NM.
LNAV flies obviously the wrong direction - or?! No holding is active, CMD C is active, LNAV and VNAV?
Any comments...
Join Date: Jan 2001
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They may have been in Heading select then re armed Lnav to follow the flight plan. N19 is 78 miles behind the a/c as seen on the ND. Can happen if you dont update the next way point whilst in Heading mode.
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Quick question from an SLF?
You can see what looks like the captain's right shoe - do the seats go back far enough you can rest your feet on the console like that?
Thanks
You can see what looks like the captain's right shoe - do the seats go back far enough you can rest your feet on the console like that?
Thanks
Join Date: Jun 2001
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My eyes aren't what they used to be but I swear the Captains FMA has "LNAV" annunciated which is really confusing - and I fly the things!
Join Date: Jun 2001
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Also note that the right FMC CDU is on Pos Report pg & the active "TO" waypoint is not N19 but appears to be a lat/long waypoint. Very strange indeed.
One of the times it wud be a good idea to go HDG SEL while you're figuring out what on earth is the matter!
One of the times it wud be a good idea to go HDG SEL while you're figuring out what on earth is the matter!
The ND displays the wind with reference to magnetic north (when the HDG switch is in NORM as it is in the picture), the FMC displays the wind with reference to true north so that explains that.
It does indeed appear as if they have bypassed a waypoint, the RHS FMC shows the NEXT waypoint as TTF(?)3 and the ETA for N19 active waypoint according to the RHS ND is 9 minutes before the estimate for TTF3, according to the map the aircraft is about to overfly TTF3. My guess is that when LNAV was reengaged a NOT ON INTERCEPT HEADING message would have been displayed and ignored, I don't think the logic would start a turnback. Anyhow - I'm sure they realised shortly after the picture was taken!
It does indeed appear as if they have bypassed a waypoint, the RHS FMC shows the NEXT waypoint as TTF(?)3 and the ETA for N19 active waypoint according to the RHS ND is 9 minutes before the estimate for TTF3, according to the map the aircraft is about to overfly TTF3. My guess is that when LNAV was reengaged a NOT ON INTERCEPT HEADING message would have been displayed and ignored, I don't think the logic would start a turnback. Anyhow - I'm sure they realised shortly after the picture was taken!
