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Guest Chief Wiggum

KSAN Depature

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Guest Chief Wiggum

Hi guys. I planned a flight from KSAN to KSFO, and selected LNSAY2.FALCC as my SID (I'm using the defualt one). I noticed that after I reach 4000' I get a route discontinuity and have to manually turn and intercept radials. Is that what happens in the real life (turn and intercept using HDG) or in real life I would be able to use LNAV to fly the entire SID?NOTE: After I pass BOKNE, I'm able to activate LNAV normally.CHART: http://204.108.4.16/d-tpp/0405/00373LNSAY.PDFThanks,

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Bernado,When you load your flight plan, you should check the "legs" page to make sure you have NO discontinuity. Sometimes this problem is caused by your inital flight plan having the sid in it and then you select the SID from the FMC which will induce a discontinutiy, the same can also happen when you do a STAR this same way. I try to plan my flights with the SID/Stars already in them via FSBuild V2. That program has an excellent SID/STAR database build into it. Then I don't have to monkey around with the same items in the FMC. Just a matter of choice. If you want to use the PMDG FMC's SID/STARS then you ALWAYS should check the "legs" page for discontinuty as it is inserted in your flight plan. Easy enough to fix, just go to the first waypoint after the discontinuty and then insert it back to the the discontinuty.In real life you don't have to fly manual until you get to the proper point.Hope this helpsBob

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ATC perspective:This particular KSAN DP actually calls for a hdg to be flown. If taking off from Rwy 9, you should manually turn left hdg 290 to intercept the MZB 314R, then track outbound to BOKNE... Rwy 29, ATC would expect you to turn right hdg 297 to intercept the OCN 155R, then track inbound to BOKNE... In some cases depending on the existing traffic situation, ATC will issue a hdg different than what the DP calls for.Hope this answers your question.Ken

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Guest Olivier

Hi,Just as a complement to Bob's answer : when you add a SID, it will not just add it to the flight plan you already entered. it will let you choose which point of you flight point you want to fly to after the SID. It can happen that the first point of your flight plan is situated before the last point of your SID. in this case, just adding your flight plan to the SID would make you go back which would be stupid and dangerous (SID are meant for all planes to follow the same departure). So, after choosing the SID, you have to close the discontiunuity with whichever waypoint of your flight plan. I do not know if the "pre flight complete" will display if there is a discontinuity in the route. In theory, you should have got a warning.Happy flyingOlivier

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Guest Chief Wiggum

Bob: If I delete the discontinuity, after I reach 4000', I'll head to BOKNE (no matter what HDG). The correct procedure is turn to 275 and intercept R-314 MZB. So I think this PMDG SID is incorrect. True?Olivier: My first waypoint is after the SID final waypoint.

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Guest stang

Hi there Bernardo.>The correct procedure is>turn to 275 and intercept R-314 MZB. So I think this PMDG SID>is incorrect. True?No. I just checked the SID and it is correct. The problem you have is that when the FMC encounters a turn of about 180 degrees or more it inserts a DISCO. The left turn to 275 degrees is about 180 degrees so the FMC inserts the DISCO after the 4000 foot waypoint. The way to fix this is to add another intermediate waypoint right after the 4000 foot waypoint so the plane gets turned in the correct direction and makes that final turn to 275 degrees much less than 180. How? I know of two ways off hand.1. Get into a flight planner and plot out the course. Guess what the turn will look like and place a waypoint at, say, midpoint of the turn. Determine the Lat/Long of that waypoint and add it to the SID as a FIX. This will get the plane to make two turns to get to 275 degrees. This sort of fudging is described in my tutorial available in the avsim library.2. I have not tried this one yet but it seems to me that in this case where you are climbing through 4000 feet you could add another 'heading until altitude' waypoint. Perhaps "HDG 03 UNTIL 4500" would work in this case. I picked 03 as it is a 90 degree left turn and 4500 feet to give the plane enough time to complete a good portion of the turn. In this case it is not important that it complete the 90 degree turn only to make the final turn to 275 degree substantially smaller so that the DISCO is not inserted. Again, I'll have to test this to insure the theory works though.Hope this helps.Terry

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Guest stang

Hi. Me again. I just tested my theory and it worked, with a modification. I had to change the 4500 feet to 5000 feet. On the display in plan mode the turn looks like a square turn but in the air it was almost a smooth continuous 180 degree turn to 275 degrees. The SID LNSAY2, RNW 09 transition can be changed to add the new waypoint as follows.... TRK 93 UNTIL 4000 TRK 03 UNTIL 5000 TRK 275 UNTIL ...I will change my master DAFIF database to include this extra waypoint so the DISCO will be eliminated in the next cycle, 0406.Thanks for catching this.Terry

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Guest Chief Wiggum

Thanks Terry for correcting it! :)I was looking for the KSFO plate and found that I have to cross MENLO at 6000', and descent to 3200' for the next waypoint (CEPIN INT). The thing is that the distance between MENLO and CEPIN INT is 4.4NM, and I'm unable to descent from 6000' to 3200' in 4.4NM and maintain a speed < 250 knots. Is that the correct procedure or misunderstood something?BSR STAR: http://www.airnav.com/depart?http://204.10...00375BIGSUR.PDFRunway 28R approach: http://www.airnav.com/depart?http://204.10...5/00375I28R.PDFThanks,

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Guest Chief Wiggum

UP!Thanks,

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Guest Chief Wiggum

No one can help me with this one? :(

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Guest tmetzinger

>Thanks Terry for correcting it! :)>>I was looking for the KSFO plate and found that I have to>cross MENLO at 6000', and descent to 3200' for the next>waypoint (CEPIN INT). The thing is that the distance between>MENLO and CEPIN INT is 4.4NM, and I'm unable to descent from>6000' to 3200' in 4.4NM and maintain a speed < 250 knots. Is>that the correct procedure or misunderstoodLooking at the arrival, 6000 is the MINIMUM altitude for the leg between BOLDR and MENLO, and unless ATC tells you, you're not required to cross MENLO at 6000.Now, on to the approach. MENLO is an IAF, and as you transition to the approach at CEPIN, 3200 is again a MINIMUM altitude, unless ATC gives you specific crossing instructions, you don't HAVE to intercept the glideslope at CEPIN, since AXMUL is the Final Approach Fix.What I'd do on this approach is slow down to no more than 200 knots after BOLDR and drop the gear and flaps 5 at MENLO, then reduce speed even more (180). That should let me get down pretty quickly, maybe even making the 3200 altitude by CEPIN, but certainly I could be at 1800 by AXMUL and be close to final approach speed.Don't be afraid to slow down early on approaches with steep gradients - ATC will understand. The gear is MUCH more effective than speedbrakes for descents.

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Guest Chief Wiggum

Thanks for your help, Timothy. I thought I was supposed to extend my landing gear ONLY after intercepting the localizer. :)I'll do this approach again.EDIT: On VNAV approaches, after extending gear and flaps it will automatically increase my descent rate to maintain 180KTS maximum? What about spoilers? Not needed?Thanks,

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Guest tmetzinger

>Thanks for your help, Timothy. I thought I was supposed to>extend my landing gear ONLY after intercepting the localizer.>:)>>I'll do this approach again.>EDIT: On VNAV approaches, after extending gear and flaps it>will automatically increase my descent rate to maintain 180KTS>maximum? What about spoilers? Not needed?>Thanks,On a VNAV PTH approash, the airplane just maintains the descent path calculated by your altitude constraints, doesn't think about speed at all.That said, if you were getting OVERSPEED disconnects before, adding the drag should help. Put in both speed and altitude constraints in the FMC, use the gear, and see what happens.

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Guest Chief Wiggum

I did this approach again and everything was perfect, except that after getting a message in the FMC saying that it would be a steep descent, I got this message: "DES PTH UNCHIEVABLE". VNAV disconnected. What does this mean and what I am supposed to do to avoid it?Thanks,

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Guest Chief Wiggum

Hmm ... UP!

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Guest tmetzinger

>I did this approach again and everything was perfect, except>that after getting a message in the FMC saying that it would>be a steep descent, I got this message: "DES PTH UNCHIEVABLE".>VNAV disconnected. What does this mean and what I am supposed>to do to avoid it?>>Thanks,To me it means the FMC is still not 100% correct, as I've gotten this disconnect when the path was perfectly flyable.But, this may be unflyable as entered, so be a real pilot and use the VS mode to get down.

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Guest Chief Wiggum

But ... shouldn't it descend as quickly as possible and *try* to be at the selected altitude even if it's not possible? Is it a PMDG FMC bug or I should use VS on steep descents?Thanks,

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Guest Chief Wiggum

By the way, when I have my gear down VNAV start to behave strangely. It tries to speed up using a higher descent rate and don't care about the planned altitudes. What is happening? :(

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Guest Chief Wiggum

UP ... :)

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Guest lamont

Bernardo:For what it's worth, I've flown that star hundreds of times and 90% of the time ATC(Vatsim) has cleared me to cross MENLO at 4000' - 4500'.

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