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Guest Chunt16307

Runway Course Errors and FMC speed constraints B737

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Guest Chunt16307

Hello Fellow Captains I am experiencing a problem with FMC runway course errors. On the approach page it shows the ILS course one degree off from the actual. I usually refer to an approach plate so I know the correct course and that is what I enter. I tried updating the AIRAC but still have the errors. Secondly,and more confusing to me is adding a speed constraint to a waypoint.I usually like to enter a speed constraint to slow the aircraft down prior to the IAF of the runway I am landing on so that I can get down to the lower speed in plenty of time.Most times the autopilot flies through the way point without a deceleration and shortly thereafter I get a VNAV Disconnect. I usually then just use MCP the rest of the way. My understanding was that I should be able to have the autopilot/FMC fly to the localiser intercept point at a speed that was programmed in the FMC but I usually have to go MCP and do it myself. As an example I was flying into KPHL on a Dupontr arrival. The FMC had me scheduled to cross Dupont VOR(the IAF) at 240 kts which is a bit too fast. I typed in 190/ and LSKed it to the waypoint but there was no decel and the plane went through DOQ at 240 kts. I am programming this restraint while still in the cruise so there is plenty of time for the execution. Anything you folks can do to enlighten me would be greatly appreciated. Many thanks, Chuck

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Guest Boaz

Your charts are outdated...Heading changes every year in some places...Boaz.

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Maybe not. The current chart for LAS ILS 25L disaggrees with the FMC by one degree. I just shrug my shoulders and set the course for what the FMC wants. Fortunately, the error for an ILS is insignificant. The LOC deviation is the same no matter what you set the course to unlike a VOR. Either you are on course or not, setting the ILS course is a good flying skill for other reasons.


Dan Downs KCRP

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Guest Chunt16307

I just checked the charts for Runway 9L at KPHL and the course printed there is 085 degrees which disagrees with the 088 degrees showing on the FMC. If I am doing a full auto-land the aircraft would miss the runway as MSFS has the course at 087 degrees. It is not all that much of a problem as I usuall hand fly it from about 2500 and in. Thanks for the answers Chuck

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