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rgamurot

RVSM on International Routes and Step Climbs

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This is a question that always bothered me but I never really bothered to ask until my FMC started going crazy (again). Right now I'm flying from Heathrow to San Francisco. Now the UK follows ICAO separations and the US follows RVSM. Also, I noticed that since North Atlantic Tracks are pretty much one way streets, it doesn't matter too much what altitude you're at. I was flying with ICAO step climbs over the UK, and 1000ft step climbs over the North Atlantic. I was at FL350 and descended to FL340 over Canada (Where I am right now) for RVSM. When I set the STEP CLIMB to 2000, I got FL350 instead of FL360. Also, after FL350 is FL370. :-hmmm If I'm flying to or from any country into or out of the US, what do I do in terms of valid altitudes?Oh, and I almost forgot, what's with my FMC? Why did it give me a 1000ft S/C first then a 2000ft one? I swear I'm getting ready to tear this thing apart!:-8Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg


Ryan Gamurot
 

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Ryan,>Right now I'm flying from Heathrow to San Francisco. Now the>UK follows ICAO separations and the US follows RVSM. Also, IAre you sure about UK? I always thought that the whole of Europe migrated to RVSM in 2002.>noticed that since North Atlantic Tracks are pretty much one>way streets, it doesn't matter too much what altitude you're>at. This is worked out with OCD (Oceanic Clearence Delivery) at Gander and Shanwick. >I was flying with ICAO step climbs over the UK, and 1000ft>step climbs over the North Atlantic. I was at FL350 and>descended to FL340 over Canada (Where I am right now) for>RVSM. When I set the STEP CLIMB to 2000, I got FL350 instead>of FL360. Also, after FL350 is FL370. :-hmmm Yeah. If you put ICAO into the STEP CLIMB entry you need to understand ICAO flight level rules. If you want even 1000 feet climbs you enter 1000. This way you would have had your step climb from FL340 to FL350. I remember Dr. Vaos had a lengthy post about the step climb rules in the FMC. It is IIRC quite complicated.>Oh, and I almost forgot, what's with my FMC? Why did it give>me a 1000ft S/C first then a 2000ft one? I swear I'm getting>ready to tear this thing apart!:-8As stated above. The reason being you entered ICAO and not 1000 in the STEP CLIMB entry.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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UK is RVSMthe north atlantic airspace is also RVSMRVSM airspace extends from FL285 to FL420 (so in usable fligth levels FL290 to FL410)Jan

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I can't keep track of who's RVSM and who's ICAO anymore. Thanks for that. Do you know where I can find a list or picture of RVSM and ICAO areas? Anyway, in the Step Climb box I first had ICAO. Then I changed it to 1000. No problem. Then I changed it to 2000 and I got a 1000ft S/C from my even altitude to an odd one (no pun intended) and then a 2000ft S/C after that.Simply put, here's the step climbs I put in my FMC and what the valid altitudes I got were.UK:ICAO Step ClimbFL310,FL350North Atlantic:1000 Step ClimbFL320,FL330,FL340,FL350Canada:2000 Step ClimbFL340,FL350,FL370For some reason, the FMC wanted to keep me on odd altitudes. That's what I don't understand. I couldn't switch to even altitudes unless I was at an odd altitude with 1000ft S/C.Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg


Ryan Gamurot
 

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Dear Ryan,Search for an older post of mine here with keyword "hemisperic altitude lock".The FMC did exactly as it should. In fact every (real) big Boeing FMC does exactly the same. So please don't tear it apart. It took a lot of time to make it exactly as it is.QUIZ : (a) How could Ryan G. break the hemisperic altitiude lock ? (:( My initial cruise altitude as set in PERF page is FL280 (for some reason). The optimum altitude is 32900. What is the first step altitude suggested by the FMC with stepping scheme 2000 ? What is the first step altiitude with stepping scheme ICAO ?No prizes !Best,Vangelis===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================


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E M V

Precision Manuals Development Group

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Yes !===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================


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E M V

Precision Manuals Development Group

====================================

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>Search for an older post of mine here with keyword "hemisperic>altitude lock".I tried but believe it or not, this is the only topic that pops up with the keyword you gave. I'll keep looking and try to see what comes up.EDIT: Nevermind, someone just posted the link.>QUIZ : >> (a) How could Ryan G. break the hemisperic altitiude lock ? Do I enter 2000 in my step climb then enter 35000 under LSK 1R.> (:( My initial cruise altitude as set in PERF page is FL270> (for some reason). The optimum altitude is 32900. What is the>first step altitude suggested by the FMC with stepping scheme>2000 ? What is the first step altiitude with stepping scheme>ICAO ?FL290 with 2000 and with ICAO, wait, shouldn't it be FL290 too?>No prizes !Aww:(Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg


Ryan Gamurot
 

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>FL290 with 2000 and with ICAO, wait, shouldn't it be FL290 too?Nope :)===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================


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E M V

Precision Manuals Development Group

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"(:( My initial cruise altitude as set in PERF page is FL280 (for some reason). The optimum altitude is 32900. What is the first step altitude suggested by the FMC with stepping scheme 2000 ? What is the first step altiitude with stepping scheme ICAO ?"Eastbound or Westbound ? ;-)


Regards,

Brian Doney

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Changed it to 280 (but Ryan beat me to it) since I thought it would be a better example of the point to make...So WEST !VangelisPS. Got it thanks===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================


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E M V

Precision Manuals Development Group

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>>UK:>ICAO Step Climb>FL310,FL350>UK is RVSM so your step climb is 2000 ft .. >>North Atlantic:>1000 Step Climb>FL320,FL330,FL340,FL350>North Atlantic in MNPS airspace is RVSM: step climb is 2000 ft!>>Canada:>2000 Step Climb>FL340,FL350,FL370>if you'd climb only 1000 feet you'd be on the levels used by opposite traffic (in RVSM) .. remember, RVSM gives 1000 ft seperation between levels, so that means going in the same direction there is 2000 ft seperation .. so to summarize:RVSM airspace (that is between FL285 and FL410)- EASTBOUND LEVELS: - WESTBOUND LEVELS1000 20003000 40005000 60007000 80009000 1000011000 1200013000 1400015000 1600017000 1800019000 2000021000 2200023000 2400025000 2600027000 2800029000 3000031000 3200033000 3400035000 3600037000 3800039000 4000041000 4300045000 4700049000 5100053000 55000etc ... etc ...NON-RVSM AIRSPACE:- EASTBOUND LEVELS: - WESTBOUND LEVELS1000 20003000 40005000 60007000 80009000 1000011000 1200013000 1400015000 1600017000 1800019000 2000021000 2200023000 2400025000 2600027000 2800029000 3100033000 3500037000 3900041000 4300045000 4700049000 51000etc .. etc ..this in RVSM airspace, between FL285 and FL410 the standard seperation of 2000 ft between traffic in opposite direction and 4000 ft between traffic in same direction has been reduced to 1000 ft between traffic in opposite direction and 2000 ft in same direction ..i can assure you it's an amazing sight to see another airliner coming your way only 1000 ft above you on the same airway .. Jan

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Here is the answer :For any big Boeing jet the FMC will always suggest as first step altitude the first available (according to stepping scheme) ABOVE the current optimum altitude.Hence, in our example if your OPT ALT is 32900 the first available step altitude is (1) Eastbound : FL330 (RVSM or ICAO)(2) Westbound : FL340 for RVSM and FL350 for ICAOPoints to make : (1) The size of the first step might not necessarily be equal to the value defined in PERF (or VNAV CRZ) pages. (2) In ICAO schemes the FMC does NOT assume a 4000 step size by default. It just knows what are the available flight levels (310,350,390,430 going west and 330, 370, 410, 450 going east) and acts accordingly.Miscellaneous info : (1) All planned steps are (MUST BE) shown in the LEGS page. You can use this information when you fly online (e.g. VATSIM or IVAO) and file you flightplan. See the following example :some other waypoints and airways... BABAN UP618 RESNO/M084F340 NATF 56N030W/M084F360 NATF REDBY/M084F360 etc etc etcIn this example we tell ATC that we expect to climb and pass RESNO at FL340 then 030W at FL360 and so on. This is the formal way of doing it.(2) The OPT ALT in the VNAV CRZ page is the value at predicted top of climb while the aircraft is on the ground or during climb. This is true for all Boeing jets (think Airbuses as well). NEVER the value based on current gross weight, unless we are in cruise phase. Hence, from take off to top of climb the OPT ALT entry will either not change at all or very very slightly (100-200 feet at most). Fuel burnoff for t/o and climb is automatically taken into account. That is why this entry is blank until you insert any cruise altitude value. This is very important info for your long haul planning (and flight plan filing) for the selection of your initial cruise altitude. That's all for now.Best,Vangelis ===================================== EMV Precision Manuals Development Group www.precisionmanuals.com=====================================


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E M V

Precision Manuals Development Group

====================================

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