FLIGHT SIMULATOR X - Notes from a virtual Air Traffic Controller and occasional virtual pilot
The down-side of ATC
To Take-off, Perchance to
That dial is going
Standard words and phrases
The Phonetic Code
After the first flight by an aircraft in 1903 it was a several years before 'hands off' flying became available. The very first autopilots were quite simple in comparison with today's versions and were often simply referred to as 'George'. (Who is flying? George is!) Early versions of autopilot often had just a heading hold facility and some simply held the plane straight and level, that was about all they did. That said, even such simple autopilot functions would have dramatically eased the workload of the pilot.
Most aircraft in FSX have an autopilot fitted as standard, the very simplest version is to be found on the DC-3, the most complex on modern jet aircraft that also have auto-throttle fitted as well. As marvellous a gadget as it is autopilot is a little dumb, it only does what it is told to. If you give it sensible instructions that it can cope with it will deal with these well.
Autopilot can be engaged by whatever buttons are fitted although the main function can be engaged by pressing 'Z' on your keypad. If no other autopilot functions are enabled all this will do is hold the aircraft straight and level. That selection alone is very useful, however other functions add to the autopilot's capability. Press 'Z' again to disengage the autopilot. There will usually be a visual indication that autopilot is engaged. Disengaging autopilot will often be accompanied by an audible warning.
If you now want to fly a particular course or heading dial the heading on the autopilot panel or the gryo compass and then press the 'HDG' on the autopilot, that will steer the plane and then hold it on that selected heading. You must do this in that order or else the autopilot will turn the plane onto the last set heading, which may not be what you want it to do. So, set heading first, then enable the 'HDG' function. From there on until you disengage the autopilot the plane will fly whatever heading you set. Some autopilots have a function to regulate the rate of turn onto a heading as well.
If you want to fly a particular altitude, set the altitude on the autopilot and then press the 'ALT' button. Whatever your height is the autopilot will climb or descend to the selected height. You can usually alter the rate of climb or descent as well. You must set the altitude before you press the 'ALT' button - by default the altitude is set to 0 feet, if this is the case there is a danger you will instruct the autopilot to fly you into the ground!
Just the 'HDG' and 'ALT' functions alone dramatically ease the workload of the pilot. But, don't forget that once you engage the autopilot any control movements you make will have no obvious effect, 'George is flying'. If you have made any control movements and then very shortly after disengage the autopilot there is a danger that the autopilot will have left the control surfaces unevenly trimmed. The danger here is that upon switching off the autopilot the plane may lurch suddenly one way or other. If for any reason you want to fly manually you have to disengage the autopilot first.
Another useful autopilot function is that of 'NAV', Navigation hold. This is where you pre-select the course (not heading) to home in on a VOR beacon radial. For example, you want to fly 050 degrees towards a beacon but are flying 030. Set the course (not heading) to 050 and engage the 'NAV' function. When the plane intercepts the 050 radial of the beacon it will then turn on a course of 050 from the previous heading of 030. The beacon could be any VOR you choose (so long as it is in range).
There are a few other autopilot functions: 'APP' is for making the autopilot fly the approach for you via a ILS/DME facility tuned into via the NAV 1 instrument (this is not autoland by the way). 'REV' can be used to make the plane make a reverse course turn onto a VOR heading. As clever as the autopilot may be it has limitations. For example, don't expect it to fly an approach for you if you are flying at high speed and altitude just a few miles from the runway, it won't do that for you.
Lastly, a mention of autothrottle. When used it will regulate the engines to control your speed, either knots or Mach number. It can also be used to regulate engine speed alone, irrespective of airspeed. Autothrottle can also be programmed to apply 'TOGA' (Take-off/Go around) power. When this is selected the engines will produce full power for take-off or go around. On landing the autothrottle MUST be disengaged, a common mistake I see is a plane landing but then failing to stop on the runway - the pilot wants to land and is trying to lose speed, but the autothrottle is trying to maintain airspeed, an unhappy tussle that the pilot will lose! The above describes the majority of autopilot functions, fuller descriptions can be found in FSX's Learning Center.
In the early days of radar all aircraft appeared on the radar display and operators may not have known who was who. This lead to the development of IFF (Identification Friend or Foe) that enabled planes to identify themselves if they were friendly or hostile, quite useful in a state of war! The modern equivalent of IFF is the transponder.
There are two types of radar return seen by operators; the primary return is seen as a single unidentified blip on the screen; the secondary return provides the radar system with an identity that is provided by the transponder. With each sweep of the radar the plane itself returns an echo to the radar receiver but with each radar sweep an activated transponder is 'interrogated' and itself sends back data to the radar receiver. In real aviation the transponder has several modes that are not exactly replicated in FSX but I need not go into them now. Even so, transponder use in FSX varies from session to session and in some cases has little use at all.
The main information sent back by the transponder in modern aircraft is the four-digit code entered into the transponder, and the aircraft's altitude. Modern radar sets are linked to computers that then assemble the radar returns and transponder data to assemble on-screen a single blip for each aircraft along with its identity, speed, and altitude. Successive radar sweeps are saved electronically to show the track of the aircraft - all the information an ATC needs to know. Further processing can then display an aircraft's callsign rather than the four-digit code. This four-digit code is usually known as the 'Squawk Code'.
In FSX aircraft the transponder, where fitted, has some of its functions limited and in ATC controlled sessions it may not see much use. The default code entered into FSX transponders is '1200' which is the North America airspace transponder code for VFR traffic. (Incidentally, this default code is used in UK airspace to identify aircraft engaged in NATO operations, 7000 is used for VFR traffic!) In real life transponder codes are divided into blocks for use in certain parts of airspace, some specific operations have their own unique code(s). Once allocated, a squawk code is usually reserved for that aircraft for the rest of its flight.
In FSX transponder codes could be used in several ways. For example, aircraft staying in the pattern could leave their transponders set to '1200' but outbound aircraft could 'squawk 2000', inbounds '3000', perhaps transiting aircraft could be told to 'squawk 5000'. Even such simple allocations of codes can help an ATC know what an aircraft is up to (the squawk code can be seen by ATC's in the 'Session Info' display). Some FSX servers often make use of real aviation squawk codes to preserve realism. (In UK317 ATC sessions a series of squawk codes is sometimes used to assist ATC, see UK317 Squawk Codes for further reference.)
There are special transponder codes used in real aviation that enable a pilot to tell ATC something about their aircraft and these can be useful in FSX as well. These are:
There are add-ons for FSX that enable another function of the transponder. One of these is 'Squawk Ident', a button on the transponder which when pressed by a pilot makes his ATC radar trace glow brighter that the rest of the aircraft traces to help draw attention to that aircraft. This could be useful in situations where an ATC radar display is very cluttered with aircraft.
A question I sometimes get asked in ATC sessions is how long it will take for a plane to get to a certain point. This is not a very easy question to answer in a snap but the table below may help calculations. For example, an aircraft with a ground speed of 150kts will be travelling at 2.5 miles per minute. If the aircraft is 50 miles away it will take 20 minutes to travel that distance.
Another example, if an aircraft is 250 miles away and travelling at a ground speed of 350kts it is travelling at 5.8 miles per minute and will take 43 minutes to travel 250 miles. The timings quoted in the first table are rounded up or down to the nearest minute, to the nearest hour in the second table. Times of an hour or more are highlighted in pink. There should be enough data in the tables to cater for most eventualities. These tables were prompted after several requests from pilots asking how long it would be until they land.
On occasion ATC controlled sessions can become hectic even with only a handful of aircraft in session, this is especially so when those aircraft are all trying to land. This is where ATC can become overloaded; there simply isn't enough room to accommodate everyone trying to get into an approach pattern. Add to this other aircraft joining a session or requesting movement, let alone those wishing to take-off, an ATC might be forced to make what may initially seem to be peculiar instructions to pilots. Quite often an extended downwind or base leg creates enough room to start to get planes lined up. The trouble is that with aircraft at different height and speeds the whole picture can be very confusing. Part of the 'art' of ATC is to get planes well separated and lined up, yet at the same time bear in mind what each plane is doing, and what it will be doing in a few minutes time.
But sometimes there simply isn't the room to accommodate all aircraft and one ends up with the situation where it is necessary to ask pilots to fly in such a way as to create enough room. A simple expedient is to ask a plane to make a left or right orbit. In this the plane turns a complete circle coming back onto the same heading again. This simple manoeuvre can buy a few minutes or miles and may be enough to permit a plane to carry on without further delay. (To date the most extreme case I have encountered was when I was requested to make 5 complete orbits!) On occasion I have asked a plane to make a three quarter turn onto a heading. For example, a plane is flying 180 and would normally turn left to make an approach on 090. But a right turn onto 090 will delay the plane's approach slightly creating some room.
For a variety of reasons so many planes may be trying to make an approach, all from different directions, speeds, and heights that it is necessary for them to enter a holding pattern, something that often happens in real world aviation. In simple terms this is where a plane goes to a predetermined point such as a radio beacon and then flies a racetrack pattern above it until such time that there is enough room for the plane to start making an approach. I have heard of real life cases where a plane has spent up to 45 minutes holding although one hopes that is an extreme example.
Such holding patterns are predefined in approach charts but the chances of every FSX pilot having such charts is small (in real aviation they would have these charts as a matter of course). So, a simple solution in the context of FSX would be that if an ATC asks you to enter a holding pattern the ATC would give you directions to the beacon. From there you would circle overhead the beacon until such time that there is room for you to enter the approach pattern under the direction of the ATC.
To date I have not had to make a plane enter a holding pattern although on one occasion a pilot offered to do so. In the event I asked him to hold at a beacon, he flew one complete orbit overhead the beacon by which time there was enough room to vector him onto approach. For a variety of reasons holding patterns in FSX may not be practical as a matter of course, it would depend on the capability of the pilot and just how congested airspace is. My point here is that at times a pilot may not be aware of airspace congestion and may be asked to do things that at first are puzzling, annoying even. But were the pilot to see a replay of the ATC display it would make perfect sense.
© Derek Haselden 2017