Flight Planner - Which Route To Use?

[Steve C 0]

When you plan a route you have the choices of direct GPS, low and high altitude airways or VOR to VOR. Are there any rules as to which you should use, does it depend on anything like distance, aircraft or cargo?

Thought it was time I learnt to do things properly!

[Longbeard 0]

I would like to learn more about this as well, great question!

[allardjd 1,853]

In the sim I guess it doesn't really matter. You can do whatever tickles you.

 

In the RW, for VFR, again, you can do what you want, but have to stay out of restricted areas and mind all the Ps and Qs of airport traffic areas and such things. Also, in the US, VFR flights go at thousand foot intervals ending with 500, so, 2,500, 3,500 etc. IFR flights are on the thousands. All flights above the transition altitude (18,000 in the US) must be IFR.

 

For IFR, the way it works is that you file a flight plan with the detailed routing you want. When you are ready to fly and contact Clearance Delivery to get your clearance, it may or may not resemble what you submitted. The FAA and the other authorities outside the US can amend it as needed to fit you into the traffic flow.

 

Direct GPS is often not approved except for long overwater flights where there are no navaids or for relatively short flights where following the airways is not really practical.

 

The ATC systems are optimized for having the bulk of long distance traffic (say over 200 NM) follow the airways as much as possible. If everyone went direct, from an ATC point of view it would be chaos, given their current hardware, software, training, procedures and mindset. There are obviously areas and times when they can permit it and sometimes do, but generally, they are happiest when you're on an airway.

 

Low and High altitude airways are designated with an eye toward the navaids involved, radar coverage available, and in some cases, terrain. Often going on the airways includes some fairly radical doglegs off what would seem to be the best routes. The High Altitude ones seem worse in that respect than the Low Altitude ones, but the players who are up high are going fast and the delays are negligible.

 

A typical routing for an airways flight is Departure in the general direction you're going but linking up to an appropriate airway within about 100 NM or less. It will then follow the airways until you get close to your destination, exit the airway and take you direct to your destination, possibly with a nearby non-airways navaid on the route first. There are a thousand variations on the theme, but that's not a bad general description.

 

The airways are defined by VORs and so your path is a zig-zag between them. That seems inefficient, but it keeps everyone on the highways and counter-flow is separated on the airways at different altitudes. Airways are defined as eight NM wide, so you don't need to be right on the center-line to be legal. Also, if you look at the difference in distance between direct GPS and airways, it's often surprisingly little - usually 5% or less.

 

The compromise is VOR to VOR navigation which sounds the same as airways, but isn't. Not every pair of VORs has an airway defined between them and it can be convenient to follow a string of them from where you are to where you want to be.

 

In the final analysis FS will let you do whatever you want and never denies what you file. I find that VOR navigation, whether on defined airways or not, tends to make the flight more interesting and gives you more to do along the way to keep the little grey cells active.

 

Putting the Nav/GPS switch on GPS and putting the AP in NAV mode may be flying, but it's not navigating and that's where the fun is.

 

When you're ready to get in deeper, then it's time to look at instrument approaches, STARs and DPs (formerly SIDs).

 

John

[Longbeard 0]

Thank you John!-

[Steve C 0]

Thanks for going into so much detail John, really interesting and useful.

[Longbeard 0]

I have another question if you don't mind. Now that you have gotten me up to speed on VOR, I prefer that method. Could you tell me what the correct way to determine the heading to a given VOR? I look on the map in game, but it doesn't seem to include that info. Obviosly it would depend on your location relative to the VOR in question, but how should I be determining this?

Thanks again!

[simi_av8r 0]

John, i thought i knew the answer to this, but it seems i too have been enlightened by your wisdom!! As they say, every day is a school day!!

Thanks!

[allardjd 1,853]

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As they say, every day is a school day!!

 

Dead right, Simi. It's a bad day if you haven't learned something from someone. I spent a couple of hours yesterday evening with a fellow member from our local flight sim club. He's done the Instrument Rated Commercial Pilot thing a great deal in the past and is a pleasure to listen to. It was a good experience.

 

Quote

I have another question if you don't mind. Now that you have gotten me up to speed on VOR, I prefer that method. Could you tell me what the correct way to determine the heading to a given VOR? I look on the map in game, but it doesn't seem to include that info. Obviosly it would depend on your location relative to the VOR in question, but how should I be determining this?

 

Well, I guess there are two scenarios here. They are...

 

1) If you are able to receive the station - this one is dead-easy. Tune the station, punch up the audio and listen to the Morse ID to be sure it's the one you think it is. Turn the OBI knob until you get a centered needle with a TO flag. That's the bearing to the station. The heading to the station may be a little offset due to the effects of wind.

 

2) If you are not able to receive the station - Use the Mark I eyeball on the map and estimate the bearing. If you can come within 15 degrees that's plenty close. You can easily get away with a 30 degree error unless you're a long way from the station. Fly on your estimated heading (maybe allowing for wind if it's likely to be a factor) with a NAV radio tuned to that VOR and the audio for that radio turned on. When you hear the ID Morse, see 1 above.

 

----------------------------------------------------------

 

If you have not looked at a sectional or an IFR chart, you should, just to get a feel for what's there. VORs have a compass rose superimposed over them on the charts and those make eyeballing the required heading infinitely more accurate.

 

Bear in mind that the maps and charts are usually oriented with true North (there are a good many exceptions to this with IFR charts) and VOR radials coincide with magnetic bearings. There can be a considerable difference between the two in some parts of the world. When looking at a VOR compass rose on a chart, it is often obvious that it is offset from true north by a few odd degrees.

 

John

[Longbeard 0]

I haven't found where to get a chart that has the VOR Compass Rose from within the sim. Is this something I need to research before the flight, or perhaps on a second PC?

Thanks John.

[allardjd 1,853]

You can pause the sim and jump out to a web browser and look up pretty much anything you want to. FS will wait patiently for you to come back. I do it all the time. If nothing else, it's useful for rest room breaks. I thought that's why they call it the "P" key.

 

Good pre-flight planning is preferred and I spend a lot of time on that, but it's not the way everyone likes to use the sim. There was a site with sectional charts on the list I put in the VOR thread a week or two ago. You can scan around them and zoom them up and see pretty much whatever you want if you're in US. If you're flying in Canada or elsewhere, I'm not so well versed in where to go for the charts and I believe they are pretty hard to come by for some parts of the world.

 

If you ever take RW flight training, at some point you will have to demonstrate exactly what's discussed above, how to find where you are using one or two VORs. Of course you'll have real charts in your lap when you do so.

 

John

[MartinW 0]

If everyone went direct, from an ATC point of view it would be chaos

Aren't they considering a system in the US called 'Free Flight'? Whereby a pilot will have the ability to change trajectory in mid-flight. With the aid of computer systems pilots will be able to make more flight path decisions independently and more direct flights?

Don't know how far they have progressed with it, and I know it's controversial.

[Steve C 0]

I think I've only just begun to scratch the surface of this flight sim stuff! :nea:

[allardjd 1,853]

You left the qualifier off when you quoted my original statement.

[allardjd 1,853]

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I think I've only just begun to scratch the surface of this flight sim stuff!

 

Don't feel like the Lone Ranger, Steve. There's a gazillion things in FS I'd like to know more about and be better at.

 

Don't worry too much about the future issues discussed just above. FS is a snapshot in time and changes in the RW don't affect it much until the next version comes out and we see what they caught and what they missed. There won't be another version forthcoming for quite a while.

 

John

[hobofat 0]

Sorry to jump in on this thread, but if you are looking for a well written tutorial on flight navigation check out this website:

[Longbeard 0]

Theres a lot of good info there, thank you Hobofat, and welcome to the forums!

[allardjd 1,853]

I've grabbed that link and it will be published in the next issue of our local FS club newsletter. Unfortunately, I just missed the deadline for the March issue, but it will go in the April one.

 

John

[wisemanp 0]

Having a million and one times flown IFR in an Airbus or Boeing, using the FMC or whatever they want to call it, I feel rather guilty about never having properly looked into real IFR flight, with proper navigation. This thread has made me want to properly learn it! It's just finding the time...

[allardjd 1,853]

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It's just finding the time...

 

Phil, it's not any easier to find the time after you retire. I've never been busier in my life. Do not interpret that as a complaint, however.

 

John

[Longbeard 0]

I've pretty well figured out how to find the VORs, tune them in, and fly between them to get where I want to go. The problem I have now, is the final leg of the flight. Many times, and especially in Cargo Pilot, the AP will be in the middle of nowhere, and won't have a VOR station on site. So I have trouble getting lined up for those, and even finding them sometimes. Even my local AP doen't have a VOR on site, so I have trouble finding the aproach heading, etc. And the localizer and glide slope is another area where I'm clueless.

Any help would be great.

Thanks!

John

[allardjd 1,853]

John,

 

I looked and your local airpatch has an ILS approach and thus a localizer.

 

The localizer is the horizontal element of an ILS and behaves pretty much just like a low-powered VOR. The image below is the ILS or Localizer approach chart for Rwy 7 at KBQK.

 

 

Here's the drinking-from-a-fire-hose version. It's kind of a big picture overview but if you understand this you'll have the general idea how it works. There are about five million variations to this. The numbers below relate to the red numbers on the chart.

 

EDIT:  The original image was lost in the great PhotoBucket debacle.  I've created a new one as best I could and inserted it into this old post but some things are different - for instance " the little ovaloid thing" referenced in 4 below, i.e. the Middle Marker, is no longer depicted on the chart version I have and probably no longer exists in the real world.  I've done the best I can to make the new image above correspond to the text below but it's probably not a good representation of what was originally there.

 

1 - The ILS frequency. Tune it on your NAV1 radio. You'll have to be within 27 miles to receive it. You will not receive the glide slope until you are within about 23 miles.

 

2 - To fly the ILS, you should have the OBI set to this radial. That's the course that you are intended to fly to the runway though there may well be a dance to get there. If properly set, the CDI (Course Deviation Indidicator - the vertical needle) will show you if you are left or right of the intended approach path, which may or may not be the extended runway centerline, but if it isn't will be within a few degrees of it.

 

3 - Is the type of approch and the runway for which it is intended - in this case Rwy 7 at KBQK. It can be used three ways, 1) full ILS with localizer and glide slope, 2) localizer only if either the ground or airborne component of the glide slope part of the system is inoperable, in which case it becomes a non-precision approach, and 3) a cirle to land, where you use the Rwy 7 ILS to get below the weather and then circle below the clouds to make a visual approach to another runway, remaining within visual conditions.

 

4 - The runway. The little ovaloid thing to the left of it is the Middle Marker. This approach does not have an outer or inner marker.

 

5 - The localizer approach path, to be flown at 069 degrees. About 99% of non-training ILS approaches are flown with ATC providing vectors to intercept the localizer. When learning or practicing or very occasionally otherwise, pilots may fly the full procedure. The full procedure begins with the IAF (Initial Approach Fix - there are two on this plate) proceeds as shown by the bold black arrow through all the necessary twists and turns, crosses the FAF (Final Approach Fix - the Maltese cross on the elevation view) and then descends along the glide slope to the Missed Approach Point or Decision Height. At that point, you must have the legally defined "runway environment" in sight or you must execute a missed approach procedure.

 

6 - Intersections, imaginary places in the sky, invariably with 5-character, supposedly pronouncable but usually meaningless names. In this case they are YOKHO and BERTT. YOKHO is defined as 11.9 DME miles from the SSI VOR on the 332 radial. BERTT is 7.5 miles from the localizer on the approach course 069 (or more correctly on it's reciporcal, 249).

 

7 - This deals with the procedure turn. It is applicable only if you use YOKHO as the IAF. If you did that you'll be flying outbound (away from the airport) along the localizer and the procedure turn is a method of getting yourself headed back inbound in a safe, defined manner. It consists of a 45 degree turn away from the localizer, a 1-minute straight leg, a 180 degree standard-rate (3 degrees per second) turn, then another 45 degree turn inbound on the localizer, using the CDI indication to tell you where to intercept it. Note that if BERTT is your IAF, you simply turn inbound at BERTT and no procedure turn is required. There's a note next to BERTT that says 1700 NoPT 069 7.5. That means you're expected to cross BERTT at 1700 MSL, no procedure turn is required and you are 7.5 miles out.  EDIT: It appears that the FAA has substituted a holding pattern in place of a procedure turn for an entry from YOKHO.

 

8 - This is the Elevation view of the approch and shows altitudes, headings and, along the bottom, distances. You can see that you are expected to establish yourself at 1700 MSL (or above) inbound on the localizer. At the FAF (YOKHO - this may be the second time you cross it if you used it as your IAF) the glide slope needle should be centered and you begin your descent, following it's guidance down toward the runway. The heavy black bar on the right side of it is the runway.

 

9 - This is the table of minimums and defines the DH (Decision Height) or MAP (Missed Approach Point) for the various types of approaches. The horizontal rows are for the three flavors of approach this chart is good for - Full ILS, Localizer only, or Circle to Land. The vertical rows are for aircraft category or aircraft classes, more or less defined by AC weight. Category A is general aviation AC below 12,000 lbs. Looking at the ILS row, the numbers mean that you must see the "runway environment" before descending below 226 MSL, and the approach requires 1/2 mile or better visibility or it is "below minimums" and cannot legally be attempted. The second set of numbers shift to AGL figures. That is the height AGL of the DH or MAP and the required minimums for the approach - a 200 ft. ceiling and 1/2 mile visibility.

 

10 - This is the missed approach procedure, which must be flown if you reach the DH and cannot see the "runway environment". It is presented in both text and pictures, for those pilots who cannot read.

[Longbeard 0]

Here's the drinking-from-a-fire-hose version.

My...what a big fire hose you have John!

I'm going to have to chew on this for a while, theres a lot to absorb there. Thank you for the info!

John