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autopilot

What does this mean in FSX?

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Hello, Guys!

 

Please see in picture below and tell me what is meant by : Direct GPS : Low-al**ude airways : High-al**ude airways : VOR to VOR : ?????????????????

 

Every type makes a different flight plan. What's the reason? What all flight plans use for and why? Can anyone explain all?

 

Flight_Planner.png

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GPS gives you a plan for a single dierct route in a straight line.

 

VOR to VOR gives you a flightplan via different en route radio VOR beacons.

 

You then have lower airways shown on your map and upper airways and you can plan a flight to stay in these as much as possible.

 

IAN

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Autopilot,

 

This should answer many of your questions and much more!

 

http://www.faa.gov/library/manuals/aviation/pilot_handbook/

 

Cover and table of contents ->http://www.faa.gov/library/manuals/aviation/pilot_handbook/media/PHAK%20-%20Cover-Preface.pdf

 

Reference Chapter 15 for navigation principles -> http://www.faa.gov/library/manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2015.pdf

 

I would also strongly suggest a read through this to help you with some questions I have seen you ask in the past. -> http://www.faa.gov/library/manuals/aircraft/airplane_handbook

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Direct GPS is a flight plan which will simply create a line between two airports which you define. It would typically be used by a light aircraft flying under visual flight rules (VFR) in good weather, where the autopilot can be slaved to the GPS to fly the route, or flown manually by observing the GPS screen to enure one is following the route, but responsibility for seeing and avoiding stuff is still largely a case of looking out of the window for other traffic when under VFR.

 

Airways, both low al**ude and high al**ude, are effectively 'roads in the sky' which used to be defined between airports and radio beacons, and often still are, but nowadays with the advent of GPS which is able to allow an aircraft to accurately position itself independent of ground-based radio aids, are now sometimes between waypoints that are not marked by ground-based aids.

 

Airways are intended to allow aircraft to all fly safely separated from one another, much like roads. And again like roads, they differ somewhat over different countries as far as rules go, but generally speaking, an airway is a corridor which is approximately ten miles wide, between two specific al**udes, where you have to get cleared by air traffic control to fly along them at a specific al**ude, so they are almost exclusively used for flights operating under intrument flight rules (IFR), where a flight plan is filed with ATC and they direct you along your route, but know more or less where you want to go anyway, so can tell you to continue along your filed flight plan route without the need to constantly tell you which way to steer and what speed to fly at.

 

VOR-to-VOR, is an older flight navigation method, which dates from the time when aircraft did not have sophisticated autopilots and flight management computers, and radar coverage was minimal. It is still used where radar coverage is not fantastic, i.e. in Central Africa for example. VOR stands for Very High Frequency Omni-Directional Radio, and refers to radio beacons on the ground which are marked on charts. They all have slightly different radio frequencies, so it is possible to tune them in on your aircraft's naviation radios, then fly by means of an instrument in your cockpit which points to where they are. Some (in fact most) VORs also have a DME capability, which stands for Distance Measuring Equipment, and those can also tell you how far away from them you are when you tune them in on your aicraft navigation radios. Thus you can plan a route which goes from VOR to VOR. You can also work out your position by tuning more than one VOR at the same time (which is why you have two nav radios). Cross referencing the two pointers on your gauges in the cockpit, then comparing that to a map will then allow you to determine your position.

 

In recent years, the advent of more accurate GPS capabilities has blurred the line somewhat on these different methods of navigation, and it is now quite common for aircraft on IFR flights to be routed directly to where they are going instead of just flying them down airways. This is referred to generally as RNAV, which is short for Required Navigation, which means that your aircraft must be equipped with enough capability to ensure that it can be automatically flown to a certain level of positional accuracy. If your aeroplane can do that, which many can these days thanks to GPS, then ATC can steer you via more direct routings, which saves time and fuel.

 

What all this means, is if you are just flying a Cessna on a pleasure flight, you would probably be best doing a direct GPS plan. If you are flying an aircraft with less sophisticated avionics, you might choose VOR to VOR, and if you are flying a modern airliner, you would probably choose an IFR plan via airways. High al**ude airways are intended for stuff like jets such as the 747, low al**ude airways are for stuff such as prop airliners, larger private aeroplanes such as twin engined Beechcraft Barons and the like, and helicopters, all of which cannot cruise at very high al**udes like big jetliners can.

 

Al


Alan Bradbury

Check out my youtube flight sim videos: Here

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Excellent stuff, Chock! I never knew what RNAV was...

 

Also, not so germane to the discussion but rarely discussed, when you're IFR you're provided separation from other IFR aircraft but not VFR aircraft. So look out those windows when you can!


Gregg Seipp

"A good landing is when you can walk away from the airplane.  A great landing is when you can reuse it."
i7-8700 32GB Ram, GTX-1070 8 Gig RAM

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This is one of the best overviews of navigation I've ever come across, and in one page.

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Also, not so germane to the discussion but rarely discussed, when you're IFR you're provided separation from other IFR aircraft but not VFR aircraft. So look out those windows when you can!

 

Sort of... it does depend on the class of airspace (and probably the country you're in). In my local AIP, in A (18k to 65k), it's only IFR, all separated. In C (typically big airports), IFR is separated from all traffic and VFR separated from IFR. In D (typically little airports with towers), IFR is separated from IFR and Special VFR (don't know if that's used in the US or Europe - SVFR is used in low visability in controlled airspace). In E (which tends to be busy areas below 18k), IFR is separated from IFR and given information about known VFR. In G it's all done by flight information, so no specific separation is given between anyone. And there are a bunch of additional provisions to some of those as well!

 

Sorry to divert the topic somewhat... now returning you to your local station: what Alan said. ;-)

 

Mike


Mike Dryden

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Just to add: the default flight planner only shows VORs and intersections when selecting Low or High Alt. airways.

I wonder how accurate that is? I understand that waypoints are generally used. Someone could chime in and correct me on that one. If the OP is flying an airliner and wishes to use waypoints, he will need to create it on his flight planner, by dragging various points along his route. If however, he selects a point that covers an existing VOR/airport/NDB/etc. then that will be allocated as his waypoint. I use waypoints for more realism, as sometimes when flying inter-continental, the FSX planner can route an aircraft in a rather misguided way.

 

Chris

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Just to add: the default flight planner only shows VORs and intersections when selecting Low or High Alt. airways.

I wonder how accurate that is? I understand that waypoints are generally used.

 

It's a good point. I'm kind of hoping he's staying below 18,000 while he's learning routes and navigation. ("Jet" routes with names starting with a J should only be used above 18,000, "Victor" routes with names labelled V should be used below.). FSX could have been smarter about flight planning...but the other tools available these days are so much smarter and make it simpler. Perhaps it would be wise if the OP used http://www.simroutes.com or FSBuild to get an idea how these things work and are frequently used. Using less busy airports will probably keep him out of SIDs and STARs until he's ready.


Gregg Seipp

"A good landing is when you can walk away from the airplane.  A great landing is when you can reuse it."
i7-8700 32GB Ram, GTX-1070 8 Gig RAM

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While I adore Alan for his writing skills and knowledge, I'd like to correct him on one thing. The term RNAV defines area navigation, not required. Perhaps he's coming from some other term there, describing RNP, which includes the word 'required'.

 

With RNAV, you generally receive the ability to fly among waypoints, being defined by their radial and distance from/towards ground stations or by coordinates only. As a rough distinction, you can't tune any of those waypoints and receive signals from them since there are no stations sending out 'I'm waypoint TANGO' but your equipment defines your relation to it, by knowing about your current location and the coordinates of that 'fictional station'.

 

It's not so much about the sheer accuracy of the navigation (since you can be fairly accurate with the older methods too), but about the ability to process raw coordinates instead of reading a needle on an instrument, showing some signal from a ground based station.

 

The process adds a redundancy in case the ground stations become inaccurate or go offline for maintenance. The processing itself is done on the plane (no ground dependency) and you will find modern systems being able to cope for all sorts of ground based shortcomings.

 

For instance, you could fly to a VOR location (by just knowing the coordinates) while the VOR is offline or sends out unusable signals since your (modern) RNAV equipment is not based on reading that one station precisely. Instead, it uses the GPS and the correlations between ground stations in reception range to define where you are and then 'knows' about the rest, so to speak.

 

What RNP (required navigation performance) mainly adds is some self-monitoring instance, allowing for a readout of the actual navigational performance vs. the required one, e.g. for approaches into tight valleys. So there would be a requirement for the accuracy to fly some approach and your equipment has to be able to check and predict the actual performance. First of all, it has to be able to achieve the accuracy (by design) throughout the approach of course.

 

For the approaches itself, the precision achieved allows for smaller airports to be fitted with precision approach procedures at locations where setting up an ILS infrastructure (ground based nav) would be too expensive in regard to the low traffic volumes or other economical or environmental factors. You mainly bring in your own equipment every time you fly that fancy plane into the airport while the folks without such equipment may be stuck at flying visual approaches or the older NDB and VOR types with way higher minima.

 

This may give an edge for the airlines operating equipped planes. Take Alaska for example. Instead of going around or even not being able to fly into the airport in bad weather, the RNP based methods allow for a safe landing while nobody has to maintain fancy ILS installations. Means that the passenger transport leads to income. :Party:

 

In recent years, the advent of more accurate GPS capabilities has blurred the line somewhat on these different methods of navigation, and it is now quite common for aircraft on IFR flights to be routed directly to where they are going instead of just flying them down airways. This is referred to generally as RNAV, which is short for Required Navigation, which means that your aircraft must be equipped with enough capability to ensure that it can be automatically flown to a certain level of positional accuracy. If your aeroplane can do that, which many can these days thanks to GPS, then ATC can steer you via more direct routings, which saves time and fuel.

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Yup, you are correct, RNAV is indeed area navigation and RNP is required navigation performance, but what I wrote in the preceding sentence was that the concept of steering stuff via the improved accuracy GPS offers, is referred to 'generally' as RNAV, which whenever I talk to pilots about it, is indeed the case, rather than what the specifics of the acronym are. Thus I find things such as IAN, RNP and RNAV all tend to fall under that reference in conversations that I've had on the flight line. Although if we are going for an expanded explanation, rather than the rough speedy guide which was my intent, then you are indeed correct that RNAV actually stands for Area Navigation these days, although it actually originally stood for Random Navigation, since ANAV would be the more logical choice if it had been Area from the start. In any case that is why I think so many pilots use it as a catch all for the general concept of more accurate positional procedures.

 

Al

.


Alan Bradbury

Check out my youtube flight sim videos: Here

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Wasn't RNAV usually done with Inertial Navigation Systems (INS) years ago? I know it was around in the 80s and, perhaps, before but I think the INS systems were subject to considerable drift because it was all done with Gyros which tend to drift...as we all know.


Gregg Seipp

"A good landing is when you can walk away from the airplane.  A great landing is when you can reuse it."
i7-8700 32GB Ram, GTX-1070 8 Gig RAM

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