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markwlee

Sim Navigation

Question

Navigating successfully the old way with Compass, stopwatch and Whiz Wheel is about as fun as simming gets.

To begin your journey of discovery, here's a couple of links:

Flight Simulator Navigation

History of Flight Simulator Navigation

Old-Fashioned Navigation

Navigation Overview - very interesting

Whiz Wheels

Online Whiz Wheel

Printable Whiz Wheel pdf

Nav Instrument Museum

The Aviator Store - maps and instruments

I love VTCs, but WACs or even the RACQ (HEMA) Australia Road Atlas (A3) are very useful. Used in conjunction with a 15cm Jeppesen CR3, Plotting Rule and a cheap Stopwatch velcroed to the desk, an F. U. N. warning should be issued.

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Great stuff Mark. Excellent articles, the best bit about this flying lark is that you never stop learning.

To add to the thread, here are a few thoughts on basic navigation from my real world flight training for those new to it all. I guess this is my idea of a rough tutorial, and is open to modification and criticism. It's not meant to be condescending - I've tried to keep it as simple as possible for those completely new to this stuff - much of it is commonsense..

Firstly I'd recommend investing in some aviation maps for the area you'd like to explore (in Australia we use WAC (World Aeronautical Charts) and VTC (Visual Terminal Charts for the immediate area around busy aerodromes) most often for real world VFR flying), a ruler, a protractor, and "wind computer" (aka "circular slide rule", "Whizz Wheel" and many other names). Virtual versions of these are available for free (see first post in this thread) but it's much easier with a real paper map and physical tools than ones on the screen. (Harder to erase the pencil from the screen too).

You can get by without any of this "stuff" if you simply want to find a field using the compass and clock, by following the directions for each field in the OZx "directions" document (method is described below).

The staples of VFR navigation are Speed, Time and Direction:

1 Speed and Time:

Use your speed to estimate the time to arrive at your destination:

For example, when flying a Cessna with a cruise speed of 110 knots (nautical miles per hour), a good rule of thumb is that you will traverse 2 nautical miles for every minute flown (now of course, you won't cover exactly 2 miles at that speed, but it is a good enough estimate).

Flying in a faster aircraft such as a Mooney or Cirrus (with a cruising speed closer to 150kts) you would cover roughly 2.5nm/min.

2. Direction:

Aviators use magnetic bearings as a reference for the direction they want to go:

In practice, in modern GA aircraft like the Cessna 172, the Directional Gyro (also knowd as the Heading Indicator) instrument is used as the primary refernce for achieving and holding a direction. It is usually a suction (from an engine driven vacuum pump) driven gyro instrument that only functions when the engine is running. As such it must be "slaved" manually by the pilot to the magnetic compass. It has the advantage of being more stable in flight, and subject to fewer errors when the aircraft is turning or accellerating than the traditional compass.

Planning a direction:

Normally the direction of the track between a departure and destination is determined by the pilot, pre-flight, by drawing a line on the map and measuring the bearing with a protractor. Then the forecast wind speed and direction is applied to this track to allow for "drift". This is one use for the "Navigation Computer" (See fiirst post in this thread). This corrected bearing is the "heading" (the direction that the nose of the aircraft will point in flight to achieve the desired track along the ground). The stronger the influence of a crosswind in flight, the greater the difference between flight plan track and the aircaft heading will be.

Holding a heading in flight:

An error few degrees here or there really makes little difference to your overall flightpath. Early in my training I remember sweating over trying to hold the DG exactly on my planned number for leg after leg of the flight. I did this so much so that my other inflight tasks (eg engine management , attempting to calm the screaming passengers, etc) suffered.

What I eventually came to accept, is that the actual wind speed and direction probably won't be the same as what was forecast (and therefore planned for pre-flight) and that the DG may not be perfectly aligned to the compass, introducing a small error.

Add in some turbulence and it seems impossible in the early stages of flight training to hold any heading accurately. But to my amazement, despite the lack of accuracy, we always arrived at the airfield that we were looking for. Don't get me wrong - accuracy is the goal, but if everything is not perfectly on the money, odds are that you will still find the field!

"Fixing" your position - Knowing where you are:

Another thing we do in real life is to take "fixes" along the way. A fix is just a matter of realising where you are on the map at a certain time. (and then using that information)

If you're only traveling a short distance (say 15 miles or less), then taking fixes enroute is not that important.Flying over a longer distance, we take fixes to make sure that we are in fact, on (or near) the planned track from departure to destination. The other use of a fix is to see if we are traversing the ground at the speed that we had estimated. I was taught to take a fix when overhead or abeam a noticeable landmark on the ground that can be also identified on the chart (assuming you have one). So lets say that on the journey you find yourself overhead a big lake that is about half way between your destination and departure aerodrome. You expected to be there after 10 minutes flying time from departure, but it only took 9 minutes to get there. So you are going faster than planned. No need to slow down, just plan to arrive at the destination 2 minutes earlier than planned (make sense?)..

A quick navigation tutorial exercise using Flightsim and OZx:

Here's the method applied to a real OZx example, in VERY simple terms (which is what we like in real world flying too. There's a lot going on in the cockpit, so best not to overcomplicate things.)

Say you'd like to go to Caboolture (YCAB) in Queensland in the Cessna 172. The OZx directions (in the OZx documents folder) tell you this: Caboolture(YCAB): YRED320009

So its as simple as:

* Teleport yourself to YRED. Easy!

*Start the aeroplane.

*Align the compass to the Directional Gyro (aka the Heading Indicator) (to do this I think you press "D" on the keyboard by default). The compass will always point to magnetic North, but it waggles around in flight so much, that it's easier to use the Directional Gyro, which we manually align to the compass. This is going to be your primary means of maintaining a heading. When you start the plane, the DG will not necessarily be algined with the compass so this must be done!!

*Check the windsock and take off!

*Climb to your desired height remaining overhead the departure airfield. (In this way, you won't be climbing enroute (on the way to the destination) and consequently covering ground at a much slower speed than you planned for).

*Now adopt the desired heading using the DG (in this case 320 degrees (we are assuming that there is no wind to blow us off track))

*Take the time. say 11:33am

*Do a quick "Departure Angle Check". This involves making sure that big features (lakes mountains etc) are positioned where you'd expect them to be from when you planned the leg. (This reduces the chance of you being wildly (usually 180 degrees) off course - it happens more than you'd think in reality , especially after 10 dizzying circuits.)

* Now, we have to traverse 9nm to get to YCAB which at 2 miles a minute (roughly what the Cessna will achieve) will take about 4 minutes.

* So add 4 minutes to your departure time. You can expect to be overhead YCAB at about 11:37.

*Hold your 320 heading and before the ETA (Estimated time of arrival (11:37)) occurs, start looking for the field.

*When you've spotted the field, treat the locals to the best landing they've ever seen!!

A note on cruising altitude:

It's much easier to navigate higher up (within reason), certainly it's easier to do so at 3500'AGL than 150' above the trees, though possibly not as exciting.

Also, to start with, turn the wind down and the visibility up, and then make things more realistic as your skills develop.

As I've said this is a very simple approach to things. Once you get the hang of it you can climb and descend enroute, fly at heights that conform with the real world cruising levels, and plan more accurately in terms of accounting for the effect of wind on heading and groundspeed. Also you can aim for harder to find fields that are farther away (so any potential errors are magnified). There are many ways to make VFR navigation more challenging, and I'm sure that they will be discussed further in this thread.

There's other stuff to learn, like "lost procedures", the "one in sixty" rule for getting back on track, and much more, but that's for later.

Pretty rough tutorial - but hopefully it's a start and will help absolute beginners build confidence without resorting to the GPS (not usually allowed in real flight training)

Thoughts?

Note: even though the actual wind was 191degres at 10knots, we still got to the field, so you can see that light wind, on a short leg, is not hugely significant.

Overhead YRED, established on a heading of 320 and levelled out almost at cruise speed. Note the time is about 11:33

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Looking outside, for a "Departure Angle Check" we confirm that landmarks (water and mountains) are roughly where we expect them to be (so we're not wildly off course).

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There's an airfield in the distance. Promising. Just like real life - it doesn't leap out of the landscape, but once you've found it what a reward!

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Overhead an airfield with the time about 11:37 - about what we estimated - reckon that's gotta be YCAB!

1241226295.jpg

The airport fits the description - 2 grass runways. Land and check with the locals that you're not at Hazelton :console:

1241290327.jpg

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Thanks for the quick tutorial Squeeker. Very entertaining.

My biggest problem is working out what cruising altitude to use. The WAC charts don't have the altitudes of the airports (I think). In real life you would look up your latest copy of the ERSA which is fine if the field is listed but the majority of fields in OZx aren't listed in ERSA. So how do you work that out.

For instance I can fly from Jandakot to Cunderdin at 3,500 feet but if I flew from Kempsey to Tony's Place at 3,500 feet I would hit a mountain before too long.

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My biggest problem is working out what cruising altitude to use. The WAC charts don't have the altitudes of the airports (I think). In real life you would look up your latest copy of the ERSA which is fine if the field is listed but the majority of fields in OZx aren't listed in ERSA. So how do you work that out. (ERSA = "Enroute Supplement Australia" - a directory of airfields and other relevent info)

For instance I can fly from Jandakot to Cunderdin at 3,500 feet but if I flew from Kempsey to Tony's Place at 3,500 feet I would hit a mountain before too long.

That's a good point Bernie. We normally get the aerodrome elevation from:

1. A privately published book called "The Country Airstrip Guide" (there are 5 of these to cover all of Australia) , this is not 100% comprehensive, and does not include most ERSA listed aerodromes. It's also bloody expensive (around $50 per hard-copy spiral bound book, or you can subscribe to it cheaper online Country Airstrip Guides ). We normally carry the relevent hard-copy of this inflight with us.

2. ERSA, and

3. to some extent, the tinting on the WAC and VTC charts. (VTC's are available online in zoomable format here Online Visual Terminal Charts )

For online flying, this website seems like it will cover most, if not all of the OZx strips:

Kwik Navigation Planner Airstrip Listing

It seems pretty comprehensive at a glance, with elevation, runway info and some other useful stuff for each airport.

Of course this is only airfield information, and doesn't help if there's a mountain in the way.. For that I guess the WAC is the best solution, or some type of flight planning software..

I'm sure others will chime in with other free resources.

Also maybe it's worth considering including each strip's elevation info in future OZx directions documents. Whaddayareckon folks?

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Thank you Sqeeker and Markwlee, I personaly started my simming life only about a year ago and as a computer illiterate. I,m enjoying every minute of it , plenty of flying and plenty of ripping my hair out - B*@$*&8 computers. Been a bit of a cheater with navigation and just got to the piont of where I really have to get down and learn this stuff. Then this thread pops up.

I think you'll see me hanging around this thread for sometime. cheers both

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Thanks for the reply Squeeker. I just checked some WAC charts that I have and each 30NM square on the map shows a maximum elevation with spot elevations of prominent features so it is dead easy to work out the lowest safe altitude.

The only problem of course is there are about 43 maps required for the whole of Australia and at about $10.00 each, that is a heap of money.

Anyone got any out of date WAC charts that they can donate to the cause?

Edited by BernieF

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Thanks for the reply Squeeker. I just checked some WAC charts that I have and each 30NM square on the map shows a maximum elevation with spot elevations of prominent features so it is dead easy to work out the lowest safe altitude.

The only problem of course is there are about 43 maps required for the whole of Australia and at about $10.00 each, that is a heap of money.

Anyone got any out of date WAC charts that they can donate to the cause?

Yeah it's rediculous $$ for the WAC charts. I'd offer my old ones up, but they are all butchered and then worn away to virtually nothing after repeated eraser-swipes..

At least they remain current for ages (as the magnetic variation isn't fluctuating wildly (yet).)

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Anyone got any out of date WAC charts that they can donate to the cause?

Let me see what I can do. I MAY be able to source out of date WAC Charts cheaply.

Darryl

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Let me see what I can do. I MAY be able to source out of date WAC Charts cheaply.

Darryl

Sound promising Darryl!

Also Mark, do you think you could add this link to the first post in the thread:

AUSNAV. (Updated April 16, 2009)

This is version 2 of Terry Mann's fantastic AUSNAV Program. AUSNAV is a preflight planning tool, that allows you to select from approximately 1500 Australian airfields and the complete list of waypoints from the ERSA. It will calculate the distance, initial magnetic heading, ground speed and ETI by just selecting your waypoints/airfields from the drop down list and entering TAS and Wind speed and direction.. Your selected flight route is plotted on an outline of the Australian continent. Use it to check your whizwheel calcs, or plan that great out back trip......before you even get the maps! There is also now the ability to enter user defined fields/waypoints. (190kb)

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Thanks for the quick tutorial Squeeker. Very entertaining.

but if I flew from Kempsey to Tony's Place at 3,500 feet I would hit a mountain before too long.

What sort of route are you flying? Maximum altitude should be 2,500. Any higher and you'll be descending before you even reach the hill. I never fly that route above 2,000 feet.

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Squeaker, I'm still laughing my head off at your description of navigating a nine mile flight. While anyone who follows your directions shouldn't get lost , it's about as "real life" as sign posts in the sky.

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Squeaker, I'm still laughing my head off at your description of navigating a nine mile flight. While anyone who follows your directions shouldn't get lost , it's about as "real life" as sign posts in the sky.

Squeaker, I'm still laughing my head off at your description of navigating a nine mile flight. While anyone who follows your directions shouldn't get lost , it's about as "real life" as sign posts in the sky.

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Squeaker, I'm still laughing my head off at your description of navigating a nine mile flight. While anyone who follows your directions shouldn't get lost , it's about as "real life" as sign posts in the sky.

A bit strong there - - - - - I don't think it's irrelevant for even a 9 nm leg. HDG, time, isn't that always the case? And he did make the statement earlier about accuracy not being so critical on shorter trips. I'd say it was sound enough advice.

Barry

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Squeaker, I'm still laughing my head off at your description of navigating a nine mile flight. While anyone who follows your directions shouldn't get lost , it's about as "real life" as sign posts in the sky.

Thanks Jack. :P

The point was to show the nav "technique" , done in a simple way. - To demonstrate it to a newcomer in a way that they could replicate and not stuff up.

I was trying to let them build confidence, rather than getting lost on a 40nm flight and giving up on the nav thing for good. (Which I'm sure would be possible for a beginnner)

9nm makes for a very quick flight, but still proves the concept.

We all have to start somewhere, no? If you think it should be differently worded/constructed then please post an example. Maybe you could write part II - a more advanced tutorial?

Edited by squeeker

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9nm makes for a very quick flight, but still proves the concept.

AND there is of course the fact that GFPT's are limited to 10 miles from their training airport...pecisely because it is FAR enough to teach SA and basic recognition of landmarks and CLOSE enough so the new student doesn't get hopelessly lost.

Darryl

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Guest hcornea   
Guest hcornea

Great to get the skills on a short flight with a good margin for error for beginners, before you do a long flight and find yourself 4nm from where you thought you were!

Sure ... you might not choose to commute 9nm in real life (you might use ground transport) ... but why crawl on the ground when you can fly ...

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OK,

Final word on the WAC Charts ....they are all securely destroyed when they go out of date. So there is no possibility of them letting old ones be issued, even stamped "not for real world navigation " or similar.

I have purchased these, current and can perhaps scan the areas required by anyone who is making flightplans, missions etc for the community, these scans could then be included with the download by the developer??. The main problem is that my time is pretty limited, so unfortunately I can't commit to scanning for everyone, as much as I would like to. I WILL do my best to do them for developers in a timely manner though.

Sorry I couldn't get hold of sets of these for wider use at a reasonable price!! At $10 each the full set runs to $430 and that is a fair bit for sim flying.

Darryl

Edited by DarrylH

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re. the 9 mile nav flight..

my first flight to Roadvale (from Boonah, about 6nm) was at last light (for a variety of reasons, point is i should have waited till next morning but i didn't want to park the acft in the open for another night) - silly decision and a lesson has been learnt

i knew exactly where the airport was from driving to/from it before this flight, but i still had trouble finding it as the sun dropped over the horizon and the light kept fading...

in fact i doubt i would have had enough light to get back to Boonah if i didn't find the airfield pretty damn quickly once i reached Roadvale

barely had enough light for a go-around but pulled off a perfect approach/landing from the north (over the power lines) under pressure

ultralights are limited to 25nm from point of departure until a navigation endorsement is obtained (i'm currently working towards that)

my last navex was Boonah/Maryvale/Warwick/Toowoomba/Gatton/Boonah and it went very well !!!

point is, a lot can go worng in 9nm...

boleropilot

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G'day Guys,

While browsing over at the Plan-G forum (a very nice freeware flight planner) I noticed Tim had posted a link to this:

Fly Better - The Art of Aerial Navigation

It's a great little book (free downloadable pdf) outlining some practical techniques for visual navigation. Well worth a read for anyone interested in the topic and I feel suited to this thread Mark has created.

I hope you find it useful.

Regards,

Serge

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I hope you find it useful.

You betcha

Thanks, Serge. Let's watch out for book 2, too. (Flying via the Art of Ballet)

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Thanks Mark, DL them both. These look like being interesting reads. anything that improves the realism in FSX is well worth the time. Teecee.

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