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Martin Georg EDDF

Relevance of Airways in the FMC

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Guest allblack

Hi all.Just curious about the relevance of Airways in both FS and real-world for flight-planning.Taking for example the flight plan below I got from routefinder:KSEA ALDER J1 BTG J1 DREWS J1 OED J126 HANDY J1 RBL KSFO Looking at the map in FS, there is only one airway (J1) between BTG and DREWS. And, between OED and HANDY J1 and J126 seem to be one and the same.Given the plane will fly in a straight line between (as an example) BTG and DREWS, what is the point in entering an Airway in the FMC; coz the plane will fly the Airway route anyway by default?This question also relates to the real-world, but obviously I can

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Guest BlueRidgeDx

Hi Tim,In short, you wouldn't enter the flightplan as you have it there. Instead, the flight plan would be filed with ATC, and also loading into the FMC as KSEA..ALDER.J1.HANDY..RBL..KSFO.ATC and the FMC are quite similar, in that they only want to know where you will join, and where you will exit an airway. They both know all the points in between.Hope that helps,Nick

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Guest allblack

Hi Nick.Not really...but thanks for trying!I still don't know - why have J1?What's wrong with KSEA..ALDER..HANDY, without the J1?Why does ATC need to know if you're using J1, when it's a straight-line between those points anyway? And that's what J1 is....Sorry if I'm being a bit thick here...CheersTimRoasting at NZWN

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Guest allblack

Just to add....I've had a look at some of the RW plans in the Flight Plan Forum, and I can't see any obvious Airways in those plans.Are Airways not used in the real-world?Hmmm...this is turning from idle curiosity into bit of a mission ; )CheersTim

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Waypoints along airways can be used to define altitude restrictions in the FMC to use it for vertical navigation. Such uses might include step climbs requested for ATC or planned descents.I noticed in the FMC planning there us a VIA field where an airway can be entered. In terms of organization it makes sense.Waypoints along an FMC break an airway into segments. Some of those waypoints may be mandatory position reporting in some areas. Sometimes showing the segment travel times can be of assistance for various applications.ATC prefers flight-plan speak in terms of airways where possible especially where FAA preferred routes can be accommodated. For the pilot referring to a chart waypoints along an airway might make it easier to relate to the chart in terms of progress.

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To look at real world existing flight plans go to www.flightaware.com. Pich a departure or destination airport. In the tables (departure, arrival, enroute) click on a flight number. A double window will open. On the right will be the current or final position of the aircraft on a route graph. On the left will be time estimates and also a field showing the flight plan exclusive of the origin and destination airports.This plan is as filed with ATC.When the plan is put into the FMC waypoints along the route may be added such as for defining altitudes or altitude ranges. I made another reply about that.

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Guest BlueRidgeDx

Tim,Everything Ron said is correct.Additionally, filing with airways is also for brevity. See how long your flight plan is...KSEA..ALDER..BTG..DREWS..OED..HANDY..RBL..KSFOWhen filing that with ATC, you'd have to read each and every fix. It would sound like this: "Seattle-Tacoma direct ALDER, direct Battle Ground, direct DREWS, direct, Rogue Valley, direct HANDY, direct Red Bluff, direct San Francisco International." It takes too long.Instead you can just say KSEA..ALDER.J1.RBL..KSFO, and it means the exact same thing. This would be pronounced: "Seattle-Tacoma direct ALDER, join JET 1 to Red Bluff, direct San Francisco International."Much better!PS - My original response to your question is in error. I read your route too quickly, and messed up my translation. It should have read KSEA..ALDER.J1.RBL..KSFO as it does in this post. Sorry.Regards,Nick

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Aircraft Boeing 737-900 (twin-jet) [b739/Q]Origin Seattle Tacoma Int'l [KSEA]Destination Mc Carran Int'l [KLAS]Route SUMMA6 SUMMA LKV YERIN J92 BTY SUNST1Date Friday, Jan 27, 2006Duration 1 hours 56 minutesProgress 1 hour 30 minutes leftis an extract from flightaware flight info as described above as filed by an Alaska Airlines flight this a.m. Note the airway included in the routeSUMMA6 would be the DP (SID), SUMMA the intersection that defines the transition from the DP to the LKV vor, then to intersection YERRA joining J92, leaving J92 at BTY transitioning to the SUNSTI STAR.(I do not think these folks will mind this pasted info as an example of how useful this site could be.)If a flight planner such as FSBUILD 2.22 has a current database, you could actually paste the route in its route window adding the airport codes and it should build you as flight plan from that.

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Guest Daniel Pimentel

I still don't know - why have J1?What's wrong with KSEA..ALDER..HANDY, without the J1?Why does ATC need to know if you're using J1, when it's a straight-line between those points anyway? And that's what J1 is....Since when are airways a straight line between two points?? An airway is a pre-determined route in the air. Fly along B520 in the Caribbean and it'll take you from St. Maarten, to St. Thomas, over Puerto Rico... And it'll do so in a curved line with small straight segments. An airway is simply a composition of points in a row that take you in either one or both directions. ATC might clear you directly to a waypoint within your airway, and the result might be you getting off the airway and back on (try it in B520 as I suggested). Hope this answers your question.Daniel P.http://www.precisionmanuals.com/images/forum/supporter.jpgMember of SJU Photography. [A HREF=http://www.jetphotos.net/showphotos.php?userid=9004]Click Here[/A] to view my aircraft photos at JetPhotos.Net!The official psychotic AA painter. :)

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Guest Daniel Pimentel

I've had a look at some of the RW plans in the Flight Plan Forum, and I can't see any obvious Airways in those plans.Flightplans as issued to flight crews tend to show the route in waypoints. Graphically:2,3+4+5+6+7,8 can also be expressed as 2,25,8 without becoming something different. Airways gather several waypoints within them, which makes it easier for ATC's and pilots to issue instructions (I can tell a pilot "continue direct JUICE, then join the B520 airway, report at STT", instead of saying "Continue direct JUICE, then direct LARPP, then direct STT, and report at STT". Also, entering airways in the FMC is much easier than entering 14 pages of waypoints. :)Daniel P.http://www.precisionmanuals.com/images/forum/supporter.jpgMember of SJU Photography. [A HREF=http://www.jetphotos.net/showphotos.php?userid=9004]Click Here[/A] to view my aircraft photos at JetPhotos.Net!The official psychotic AA painter. :)

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I imagine airways make life easier for ATC to keep track of, and provide separation for multiple aircraft. I understand that with use of FMS/GPS systems, there is a trend or desire for ATC to "clear direct" rather than require airways.scott s..

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Guest allblack

Thanks all. The comment below has made the most sense to me, and has made the light flick on!I take from this, that, for example, there could be ten Intersections/NDB's/VOR's between JUICE and STT, all along the B520 airway, but it's only the entry point (JUICE) and possible exit point (STT) that are relevant to the flight plan? Therefore it's not necessary to load them in the FMC coz the airway will bypass them anyway...Thanks again guys - much appreciated.Airways gather several waypoints within them, which makes it easier for ATC's and pilots to issue instructions (I can tell a pilot "continue direct JUICE, then join the B520 airway, report at STT", instead of saying "Continue direct JUICE, then direct LARPP, then direct STT, and report at STT". Also, entering airways in the FMC is much easier than entering 14 pages of waypoints.CheersTim

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In the FMC, if you put an airway in the VIA collumn of the RTE page, it will automatically imput all the fixes between the fix on the line aboveand the fix on the line with the airway.ExampleVIA------------TODIRECT---------SEAJ1-------------RBLThen in the LEGS page, you'll see ALDER, BTG, DREWS, OED, HANDY, RBL and all the fixes inbetween automatically entered for you.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

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Guest allblack

Really? Cool!I'll try that a bit later.CheersTim

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