Attn: Mike Leavy Need Your Expertise!!!

[dharrison]

Mike,

Hope you are well, need some procedural and system clarifications for the NG. When entering a route in the FMC, obvously most of the time you download from ACARS. Once the route is in and INIT REF is executed the FMC calcuates your planned altitudes on the LEGS Page right? Now here is the real question. When do you input the crossing restrictions in the FMC for arrivals (if not already there when loading using the DEP/ARR page)? Also, will the FMC calcuate the all the altitudes on the route without entering an approach procedure if you only enter the route to the end of the arrival. Do you need to have an approach procedure or ending runway entered before the FMC calcuates the planned alts ont he LEGS Page?

Thanks,

Don

[Maurice]

I am not Mike  but here is what Mark at SimA said about this & I quote:

"To calculate these values the CDU requires and End of Descent (EOD) altitude. It gets this from either the landing altitude of the arrival runway or from an entered LEG altitude constraint. On most approaches there is at least one altitude entered for the Inial Approach Fix."

Now hopefully Mike can confirm or question this 

Maurice

[dharrison]

THanks Maurice,

I have seen the same. Just trying to understand if it needs to be an IAP, a runway selection or a hard constraint at some point in the route (IE: Crossing Restriction in a STAR.) Just seems to me that planning an approach in the FMS at the beginnig of the flight seems counter intuitive if you are going to change runways anyway. Seems I would plan to the end of the arrival and when I get my runway assignment then input the IAP or runway.

Mike,

How do you do it in RL?

Don

[dharrison]

Now that I read Mike's post about setup and flying he said add arrival, constraints and runway expected guess. That makes sense. I am guessing you don't select the IAP just the runway?


Don

[Maurice]

Now that I read Mike's post about setup and flying he said add arrival, constraints and runway expected guess. That makes sense. I am guessing you don't select the IAP just the runway?

Don

I'm pretty sure I tried entering just the arrival runway and the altitudes were not calculated. But what I don't know/remember is if the CDU showed the runway altitude. I would think it should but maybe it didn't in which case VNAV would not calculate the other altitudes. My sim is down right away so can't verify that.

Can you try just entering a runway and see if the CDU shows the runway's altitude or whether it has to be entered manually (which really does not make sense to me). All that info is available in the database I believe and if it is, the altitude should be there when you select a runway.

Maurice

[dharrison]

I can't, it's Scott's sim. I am sure he will give it a try and report back.

Don

[MLeavy737]

Mike,

Hope you are well, need some procedural and system clarifications for the NG. When entering a route in the FMC, obvously most of the time you download from ACARS. Once the route is in and INIT REF is executed the FMC calcuates your planned altitudes on the LEGS Page right? Now here is the real question. When do you input the crossing restrictions in the FMC for arrivals (if not already there when loading using the DEP/ARR page)? Also, will the FMC calcuate the all the altitudes on the route without entering an approach procedure if you only enter the route to the end of the arrival. Do you need to have an approach procedure or ending runway entered before the FMC calcuates the planned alts on the LEGS Page?

Thanks,

Don

Don,
  Yes, in the NG's the route is loaded through ACARS. In the 500's you have to manually enter a route. And yes once the route is in and INIT REF is executed altitudes will be calculated and shown on the LEGS page.  Any hard altitudes or constraints such as (AT) (At or Above) (Below) etc. will be shown in a large font. FMC calculated altitudes will be shown in a smaller font.  The ACARS does not load arrivals or departures automatically so they will entered based on the flight plan or clearance. Normally arrivals have some type of hard altitude constraint that is derived from the database however you always need 1) verify the points on the arrival match the chart and 2) add / verify additional altitude constraints that are landing runway dependant.  The reason you want to pull up the WX for the destination and enter a RY before you depart is for time planning purposes. As we all know Airlines want to be on time.. not early bacause you wait for a gate, and not late bacause of obvious reasons. Having everything entered allows you to increase cost index or any other technique you can do to make up time the best you can if needed.
  You will still get FMC calculated altitudes without having a runway or approach entered.  All you really need is 2 airports and a cruise altitude / INIT REF page complete to get FMC altidudes. The FMC calculates altitudes by working backward.  Just having a runway in the LEGS PAGE will calculate an altitude thats 50ft above the touchdown zone and calculate a TOD point that intersects your cruise altitude. When you add additional altitude constraints prior to the runway  point, the TOD is just calculated from that new fix to your cruise altitude. If you ever in doubt what the FMC is looking at to calculate its TOD/path, just look on the DES page upper right side. That Will always show the current fix that your path is being built on.
  One last thing.. In the airplane you can just take the RY on the LEGS page, bring it up to LSK 1L, enter the course on LSK 6R, EXEC that and a lateral and vertical course will be built that you can fly in LNAV/VNAV and you will cross the threshold at 50fton course.  The RY has altitude info from the database.


hope this helps,
Mike Leavy