The cruise may be the least exciting part of a flight, but necessary. Its time to look at the “cruise” and navigation part of a flight.

In this class you will learn about:

• The use of the Autopilot
  
  
• vasFMC
  
  
• AIRAC, Procedures & Flight Simulator
  
  
• Navigating with: VOR, NDB and DME
  
  
• METAR (Weather)
  

The Flight Management System (Autopilot)

The FMS consists of the MCP (mode control panel), the FMC (Flight Management Computer), the enunciations on the Primary Flight Display and the smarts behind the scenes that you don't see. These are Boeing terms, although the names of the components in other aircraft may be a little different, the functions will remain much the same. Only complex aircraft panels will include all of these items.

The FMC is used to input flight plans and give detailed instructions on how an aircraft should fly, as well as what environment it may encounter. Often, there may not be an FMC present in smaller aircraft (in the real world), such as the turboprops that United Express flies. The FMC is more the domain of the larger aircraft that fly longer distances. In the simulation world, simple panels will not include FMCs, even for large jets. To have an FMC included as part of the simulated Flight Management System you have to get more complex simulations that
are generally payware.

The PFD enunciations along the top, will show the current and armed status of the Auto Throttle (if there is one), the pitch mode and the roll mode, as well as the Flight Director and AutoPilot status. You will generally only find these on more complex panels.

The MCP is a fairly direct way of controlling the aircraft's flight, and often people think of this as the entire "autopilot".  It can be used to override the FMC, or it is used primarily if there is no FMC present. The MCP can vary in appearance from aircraft to aircraft and panel to panel, and in particular can vary in function in simple as opposed to more complex aircraft panel simulations.

My Panel Doesn't have all that stuff! Not a problem! There is now a wonderful workaround. Free for the download, is a fairly full featured freeware FMC that gives you lateral guidance as well as vertical advisories, and it is easily added on to most simple aircraft panels. Its name has changed recently, it is now called vasFMC. If you fly mainly default or other simple panels, you owe it to yourself to have a look, your flying will never be the same again! See the description below.

FS2004 737 Classic "simple" panel MCP

As an example, below is the FS2004 default aircraft panel for the 737 Classic aircraft. Generally, MCPs contain most of the following components.

Flight Director

When enabled, it will show on the Primary Flight Display the pitch & roll attitude that the aircrft should hold, according to the active settings. This is a great aid when handflying your aircraft. Unlike in a small GA aircraft, it would be rare that an airliner would be flown just on raw data alone.

Autopilot (master switch)

Used for enabling the autopilot. If you turn it off, the autopilot will no longer control the aircraft's pitch & roll. The autothrottle is seperate from this, and will command even with the Autopilot disabled. The Flight Director will continue to show the desired pitch & roll attitude on the PFD as well, even with the Autopilot off.

Auto throttle (master switch)

Enables the auto throttle, turning it off will switch the throttle into manual mode. Smaller aircraft, such as the Turboprops and Regional Jet Turbojets usually do not include an Auto Throttle. These are expensive items in the RW, and maintaince can be a large headache. Paradoxically even some simple simulations of the Regional Jets, will include an Auto Throttle, where one doesn't actually exist in the RW.

Heading interface

Used for giving the aircraft a fixed heading to fly. Adjusting the heading is accomplished by either clicking on a knob below the numbers or on the numbers themselves. Note that Heading is not necessarily the Track. The Heading is the direction the nose of the airplane is pointing. The Track is the path the aircraft is actually flying, with reference to the ground, after being acted upon by the current winds. ATC will always ask you to fly a Heading, not a Track. Of course when flying a Heading on your own, you need to be aware of the winds, so that you can Track correctly towards your intended destination.

Course interface

Used with navigational equipment to set the radial/heading to a VOR or ILS. Note that this is where the ILS front course is entered.

Altitude interface

Used for setting a fixed altitude and/or the vertical speed in ft/min. Note that the autopilot will level itself when it gets close to the selected altitude.

VS mode is used for changing altitude, but only in limited circumstances. Examples include short climbs/descents such as changing to your next step altitude at cruise, or the final part of a non-precision approach. VS mode can also be used for idle power, or near idle power descents, if no other option is available.

VS mode can be dangerous because it can lead to a stall if not watched carefully, or alternately if used conservatively to try to avoid this, VS mode will waste fuel and time by climbing inefficiently.

LVL CHG (level change) mode, also labelled FLCH, or its more mysterious cousin VNAV should be used for most climbs and descents when available. Although simple panels do not have such functions, happily there are a variety of ways of getting around this. See the Traininng sections on the forums for tips. vasFMC provides only advisory vertical guidance.

Speed interface

Used for selecting a speed you wish the auto throttle to command. It can be selected in either IAS (Indicated Airspeed) or Mach. You will fly with reference to IAS below FL250, and generally fly a Mach Speed above FL250. Note that if the autopilot is turned off, the auto throttle will still hold the commanded speed. Speed mode should also be seldom used, if your panel allows for alternatives, namely LVL CHG or VNAV modes. Typically you will still use SPEED mode when in late approach or on final.

NAV button

Used with the navigational equipment. You need to tune a VOR or ILS, and select a radial/course for it. When NAV is enabled, the autopilot will command the aircraft to fly on the selected radial/course. Note, that it will only command the heading, not the altitude.

APP button

Turning this on will enable the same feature as the NAV button, and in addition it will control the altitude according to the glide slope. Note that it is only used for ILS approaches. This allows for flying the ILS with guidance down to 200 ft AGL, which is called a coupled approach. Simple panels do not have an autoland function, and in any case true Autoland is only available in larger aircraft designed to fly long distances. 200ft above ground level is the Decision Height (DH) for a Cat I approach, if you can see the ruwnay then you turn the autopilot off and handfly the rest of the way. If you cannot see the runway at this point, then you must go-around. Without a full autoland capability, you may not land if you cannot see the runway by 200ft AGL.

BC (Back Course) button

Used to engage the autopilot’s back course approach mode. Functions just like approach mode, except the glide slope is disabled and the autopilot’s response to a localizer signal is reversed, e.g. if the localizer needle is offset to the left, the auotpilot will turn the aircraft to the right to intercept it. On more complex panels, this reverse behaviour is corrected for, and you will see the normal cues as if you were flying a localizer approach on a front course.

737 NG "complex" panel MCP

vasFMC - a Freeware FMC

Wow, what an application! It doesn't care if you're using FSX or FS9, it works through FSUIPC, and works fine with WideFS. If you are flying freeware -- RUN, don't walk, and grab this one!

At right, the FMC "panel". I'm just taking off from KLAX, off to KSFO. vasFMC comes with a separate Navigation Display (in Boeing or AirBus type) with range control and a map mode so you can check your flight plan. It even has a TCAS and the Boeing Banana for altitude prediction on the ND! This panel is a representation of a LEGS page from an FMC, that is where you do all the input/edit and control.

Although it doesn't have full VNav (vertical) guidance, it does have a descent calculator that shows you your Top of Descent, and this keeps updating, so you know if you are on track. Even suggests a rate of descent to use, and it shows the green Boeing Banana on the ND. This green semi-circle shows you at what distance you will attain the altitude set in your plane's panel MCP (autopilot), if your current rate of descent or ascent is maintained. The combo makes planning for altitude restrictions a snap!

This thing is amazing! Hard to believe that it is freeware.

The whole flight plan can be inserted in standard format text, direct from Flightaware or Simroutes. FSBuild 2.3 (just released version) will export to vasFMC now.

If you want to edit a flightplan, the runways, SIDs and STARs are added with a click, and easily edited any number of times. Includes DIRects, easy enroute changes, even flyover points and HOLDs! Even sets the ILS up in your NAV1 radio with a single click.

Gives you all the pertinent altitude and temperature data, landing field altitude, even your current Density Altitude! 

It even uses up-to-date Airac/Procedures data. It uses the F1 ATR set, so it will continue to be updated. Shipped with an old set, but easy to update from NaviGraph if you are using that, or grab the last 0608 free data set for the F1 ATR.

AIRAC, Procedures & Flight Simulator

AIRAC

AIRAC is an acronym for Aeronautical Information Regulation and Control, but when we use the term we usually mean to refer to the complete database of waypoints, navaids and airways throughout the world. In our example route, COATE (waypoint), FNT (navaid - VOR) and J36 (Jet airway) are included in the AIRAC database. The database is dynamic, and routes & waypoints are added and deleted.

Procedures

Procedures are defined by selected waypoints and navaids from the AIRAC. Procedures include SIDs (eg. KENNEDY1), that we use to leave an airport, and STARs (eg. SAYRS1) that we use to approach an airport. These also are redefined and updated as needs change.

Flight Simulator ATC is completely SID/STAR-blind, and one of the many reasons that you really shouldn't use it. The Flight Simulator flight planner is also not set up to use STARs or SIDs directly, but at least you can input the individual waypoints and set up the route.

Keeping up to Date

There is one additional stumbling block. The FS9 AIRAC (airway & waypoint) database is stuck in 2002, so many of the current newly defined waypoints may not be in that older database. FSX is frozen at April 2006. When you encounter issues like that online, being asked to fly to a waypoint that you just don't have, be sure to indicate "unable" and request vectors instead from ATC.

If you have a pdf hardcopy of a chart, and if the latitude/longitude of a waypoint that you don't have is noted, then you could potentially input that, and then navigate as directed. But, never pretend to be able to comply when you can't! That will just compound the situation, and it is completely unnecessary, as ATC understands that not everyone has the latest databases.

The good news is that when you use vasFMC or a complex aircraft panel that uses its own AIRAC database, you can always be right up to date!

Previously the worldwide database was available for free, but it has now changed to low-cost payware from Navigraph. That is unfortunate, but the alternative was losing access to the database altogether due to international licensing issues. The last freeware set (Aug '06)  is available for download from AVSIM, and it is not that out of date at present -- search for "AIRAC" & "Richard Stephan" in the navigation section.

The world-wide procedure (SID/STAR) database may already be available through Navigraph (payware) for your aircraft, they are expanding availability to a wide variety of aircraft sims.

There also are reasonable freeware alternatives.  Planepath provides at no charge the SID/STAR database for the US, Canada & some of the UK for many aircraft panels, including vasFMC. Also users just like you & me, have taken the trouble to program the various procedures for a variety of aircraft themselves. This "third party" set of procedures is available for free download at a subsection of the  Navdata site.

Lots of choices. Together with the pdf viewable/printable charts for the procedures world-wide, some sources for these were noted in Flight Planning, you have your maps for the sky.

Navigation

VOR (VHF Omni-directional Range)

This is the navigational aid (or NAVAID) you will encounter the most. Think of the VOR as a radio antenna that sends a distinct signal along each of its 360 radials. This allows a VOR radio on an aircraft to determine the direction to the station. By convention, like bicycle spokes, radials are always considered as pointing outwards from a VOR, but logically can be considered as extending out on both sides of the VOR. One side being the FM (from) side, and the "backside" of the radial being the TO direction. The course and the FM & TO do not indicate your direction of flight (heading), but rather where you are relative to the VOR.

Now, look at the diagram at right, if you can memorize that diagram, or refer to a printed copy, you will always know where you are relative to a VOR, and how to track towards or from it, and along any specific radial if required.

There are five MFDs drawn in, as you might see them on your panel. They are meant to represent what you would see while in an aircraft in those relative positions. The diagramed white line and magenta bar on each MFD together are called a split cue CDI (course deviation indicator). The light magenta arrows note that the aircraft are all heading in a direction of 15° magnetic. The course knob on the MFD has been set to 015, because we are interested in the 015 radial. Also note, that the VOR (RBV) has a magnetic north slightly to the west (left) of true north, although the diagram is not exactly to compass scale.

Now look at MFD #1. The split needle is aligned, that indicates that you are on the VOR radial that is set as the course, namely 015. The MFD arrow is signifying a "TO" direction. Therefore you can continue your heading of 15°, if you wish to fly directly to the VOR along the "backside" of the RBV 015 radial. You are actually flying along the RBV 195 radial. Ok, that's not too hard.

Now look at MFD #2. Everything is set the same, but the split needle is now to the right. To intercept the radial, we need to turn to a compass heading somewhere on the side of the magenta needle deviation, which here is between 015° and 195°.  Because in our examples we are flying the same heading as the course we have set, here we would just need to turn to the right. You would intercept it quickest, if you turned 90° right, fully in the direction of the magenta CDI, to a heading of 105°, although that might not be practical. MFD #3 is exactly the opposite, you need to turn left.

Now consider MFD #4. The split needle is to the right, so you need to turn right to intercept the 015 radial you have set as the course. But here that radial is "FM"  (from) the VOR. If you intercept that radial, and continue on a heading of 015, you will fly away from VOR RBV. MFD #5 is the opposite to #4, you need to turn left to intercept radial 015 from the VOR.

Now, if you just want to fly directly towards a VOR, not necessarily along a specific radial, just turn the course knob until the split cue needle lines up, and ensure you have a TO indication, note the course, and then just fly that as the heading. If you have a FM indication, you will fly directly away from the VOR if you make that course, your heading. Turning the needle 180° will always switch the FM to TO, or vice versa.

The easiest way to get a better understanding of all this, is to load up an aircraft in Flight Simulator, place it somewhere relative to a VOR, and then rotate and slew around! You will have a working model you can observe. Play with the aircraft heading and the MFD course setting in various positions. It will all start to make sense!

Now, let's look at an example, it is a little tricky. Let’s say you are going to fly to the RBV VOR (Robbinsville) which is located southwest of NYC. You need to look up the frequency, it is 113.80.

You are flying from Boston, are heading southwest, and decide to pick up and track along the 050 radial towards RBV. But remember radials always point out, so that would be along radial 050 in a FM (from) direction! It is always easier to think of a TO orientation, so instead think of the 230 radial (from the opposite side) extended backwards.

Set your MFD course to 230, ensure you have a TO direction indicated, you will turn right so as to center the MFD needle. When centered, you then turn to a heading of 230 and you will be flying along the 050 radial directly towards the VOR. (figure right) This corresponds in relative position to the VOR, with MFD #2 above.

That's the theory, now you are in an aircraft. NAV1 frequency must be tuned to 113.80. As in the above exercise, the course is set to 230, because that is now your new desired radial. As in the schematic at right, you will see in the MFD (figure below) that you have a line pointing to heading 230 and a magenta bar to the right of it. With the magenta needle to the right, examining the compass markings, it shows you need to fly a heading between 230º and 50º to intercept. As you are travelling on a heading of 230º, you will need to turn right to intercept that radial. You can now choose if you want to fly to RBV by hand, or if you want George to do the work.

To have the autopilot fly you onto the 050 radial (230 course towards the VOR), again you must first be on an interception course for the radial, say Heading 250, then simply press the NAV button on the autopilot and wait. Once you get closer to interception, the autopilot will start turning the aircraft and eventually you will be flying on heading 230 directly towards RBV.

Don't forget that, if you set the MCP up as if you were going to have the autopilot fly it -- but don't turn the A/P on -- the Flight Director will still show you the course to steer to complete that task. This is exactly the course that the A/P would have steered. Don't forget to use that FD cue whenever you can, when the A/P is off.

DME (Distance Measuring Equipment)

Many VOR and ILS stations include a DME signal. This is a separate device which transmits pulsed signals that allow a DME receiver in the aircraft to determine the distance to the station. DME is an important navigational tool.

An example is on our planned departure. After take off, you are required to make a turn to the left when you are about 4 miles from the runway. On a chart this will be printed as 4 DME. You accomplish this by tuning in the station that the chart references for the distance. As you move further from the airport, the displayed DME will increase. As it appraoches 4, then you need to perform the turn.

Another example is with a VOR (assuming it is also equipped with a DME), where pilots are required to turn at 10 DME away from the VOR to follow a flightplan onto a new Jetway. As you get closer to the VOR, the DME will decrease and as it approaches 10 DME, you execute the turn.

More Navigation Stuff

There is no end of materials on Aviation Navigation, but there is one website resource that really stands out for the virtual pilot, and that is:

       Flight Simulator Navigation

This  is a comphrehensive, yet easy to follow, and entertaing read. It covers everything, including the history. It even has an optional tutorial approach included together with a custom aircraft and panel to ease you through the lessons. It is nicely indexed, and you can quickly click to just the sections that you wish to read, or you can read through the whole thing.

Bookmark it! You will likely return, and review it often.

METAR (Aviation Routine Weather Reports)

METAR’s are aviation's version of weather status. A TAF is an aviation weather forecast. The FAA and different weather services created a shorthand specification for stating weather conditions that would standardize reports across the world. This system was launched in July 1996.

You can find the reference website here:

    METAR/TAF - NOAA Satellite and Information Service

You can obtain a current METAR in a variety of places, including online on VATSIM and with ServInfo, described in the VATSIM section. Here are two websites where you can obtain worldwide METARs:

    NOAA Aviation Weather

    METAR Data Access

Here is a site prepared by an individual, listing many of the more common METAR terms and their intrepretation:

    METAR decoding

Let’s look at some example METAR’s and decode them.

KMIA 151353Z 30008KT 10SM FEW250 16/12 A3009 RMK AO2 SLP189 T01560117

KMIA – this represents the METAR reporting facility

151353Z – the first two numbers represents the day of the month, in this case the 15th, the next four numbers are the time of day in Zulu or GMT.

30008KT – this is the current wind. The first three numbers are the wind direction, here the winds are blowing from a heading of 300, the wind heading specified here is always the TRUE heading, not magnetic. The next two numbers are the wind speed, and in this case it is 8 knots.

10SM – here, we have the current visibility. When you see it like this, 10SM, you could expect the visibility to be 10 statute miles or greater, 10 statute miles is the maximum visibility distance reported.

FEW250 – this is the clouds over the facility. Here we have a layer of FEW clouds at 25,000ft above the ground. The cloud layer level is always stated as the height above the ground, not the height above sea level.

16/12 – this is the temperature/dew point in °C. In this case the temperature is 16°C and the dew point is 12°C.

A3009 – This represents the local altimeter. Here, the altimeter is 30.09 in Hg.

RMK – Anything after this is the remarks section. The remarks can be quite varied.

SLP189 - Sea Level pressure reported in tens, units, and tenths of hPa

KJFK 151351Z 36017G25KT 1 1/2SM -SN BLSN FEW008 BKN017 OVC026 M13/M14 A2985 RMK AO2 PK WND 35026/1325 SLP108 SNINCR 1/6 P0001 T11281144

Here we have another METAR; let’s go over what is different.

36017G25KT – this is still the wind, but now the wind has gusts. The readout would be, winds from 360 at 17 knots gusting at 25 knots

1 1/2SM – Now the visibility has decreased to about 1.5 statute miles. A nautical mile is about 6000 ft, so about 15% longer than a common or statute mile.

-SN BLSN – whenever we have an event like rain (RN) or snow (SN), this will appear in this section. Here we have Light Snow(-SN) and Blowing Snow (BLSN). Just SN means moderate snow, and +SN means heavy snow. We like that!

FEW008 BKN017 OVC026 – Now we have more cloud layers above us. This reports a layer of Few clouds at 800ft, a layer of Broken clouds at 1,700ft (this is also the ceiling) and an Overcast at 2,600ft. The reported ceiling will be at clouds broken (5/8-7/8) or greater. SKC=sky clear, FEW=0/8 to 2/8 sky coverage, SCT=3/8 to 4/8, BKN=5/8 to 7/8k  OVC=overcast. The cloud levels are always reported in hundreds of feet above the ground (AGL), not above sea level.

M13/M14 – now the temperature and dew point have an M in from of them. This represents the Minus symbol. Here we have a temperature of -13°C and a dew point of -14°C.

A2985 – this is the local altimeter, now at 29.85.

ENGM 151350Z VRB02KT 4000S VCSH BR FEW005 BKN006 M04/M05 Q1018 TEMPO 9999 SCT006 BKN011

This is a METAR from Europe, and as you can see, it is somewhat different from the US & Canada.

VRB02KT – this is something you will see in the US too. The winds are Variable at 2 knots. This means that the wind is shifting so much that a fixed heading can’t be set.

4000S – this is the visibility, though a little different. The visibility is reported to be 4000 meters or 4km when you look to the South.

VCSH – this is an event, here it says: In the vicinity, rain showers.

BR – mist (from French, just think "baby rain"); FG = FOG, which is just dense mist, with visibility <1000m

Q1018 – as you might know, in Europe they use QNH as the altimeter. Here the QNH is 1018 hectopascals (hPa), 30.08 in Hg

TEMPO – this is the remarks section, it means TEMPOrary.

If there are no remarks you will see NOSIG instead.