FMC Message Using Tutorial and Missed appr Problems

[Flaps30 3]

In TM's tutorial flight 4 Scenic Tour, I am baffled by an FMC message while approaching OMN. After exiting the hold at ATHOL, my FMC keeps chiming to "reset MCP Altitude". I'm at 4000 and upon checking the legs page, that's where the FMC wants me until Kizer where it has me down to somewhere around 2600. I'm about 30 miles from OMN when it starts the chime and warning. I finally reset to 2600 and the chiming stopped, but why so far from where I was to descend? Also while trying the missed approach at MCO, I am in LNAV and when the plane reaches the holding track, it turns to about 145 degrees along it and doesn't turn, but continues straight away from the track. Any ideas what I'm doing wrong?? Thanks. Tom

[Guest neerajpendse]

As you probably already know, when there is VNAV input from the FMC, it is overridden by the ALT set in the MCP window. So in order for the descent to begin after KIZER, MCP must show the next altitude (2600) ... when the aircraft's computed T/D (top of descent) point is passed, and if you do not have the next altitude in the MCP, it will chime. In order to see what is going on, could you check if the T/D point was ahead or behind you?On the second question, it is hard to say- what kind of entry was supposed to be done (what approach was it)? Did LNAV disengage? You might have to share pics before we can troubleshoot ...- Neeraj.

[downscc 1,327]

If I recall correctly, the entry to holding for South traffic in several cases run into a bug in the 737 FMC (you didn't mention aircraft or approach). When the track to the holding fix is true South, the FMC hiccups and creates a disco error.. and only in this case.The disco error is announced as a message on the FMC, but there is no way to fix it except to redo the sidstar file. You can try the sidstar file I have uploaded to NavData and AVSIM for KMCO, where I resolved the error by introducing a teardrop entry to holding (which would be a proper entry). Getting off the true South entry bypasses the FMC bug. I have found the same thing happening at several of the 50+ locations for which I have created procedures.

[Flaps30 3]

Thanks for the help guys. First of all, I will check out that top-of-descent and see if it is before or after. Secondly, the Tim Metzinger tutorial uses the ILS18R approach, but I am not sure of the heading inbound to the approach track. I will check that out to and get back to you. Thanks. Tom

[Flaps30 3]

Guys, I solved the FMC message problem inbound to OMN. There is no TD point before OMN. I must have closed the disco too soon last night. The tutorial shows selecting HAMMY after OMN, so there should not be a descent before OMN. I just selected HAMMY too soon. Regarding my other problem with the hold, see my latest post above. Thanks again, regards, Tom. td