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Voice-ATC simulation

Started by Hardy Heinlin, Tue, 4 Oct 2016 00:27

Hardy Heinlin

Some more notes on the Voice-ATC simulation

The Talk to us mode is inactive if:

- Talk to us checkbox is off
- OR transponder is set to 7700, 7600 or 7500
- OR Tower or Ground is responsible and station is >100 nm away
- OR Departure or Approach is responsible and station is >500 nm away
- OR if all of these conditions are met:
_____ + CPDLC simulation is in random mode
_____ + FMC CPDLC is logged on
_____ + FMC data link is on
_____ + FMC has an active route
_____ + FMC CRZ ALT > 18000
_____ + Aircraft altitude > 13000

The frequencies, volumes and audio preferences must be appropriately set so that the ATC voice can be heard; if this is not the case, the simulation may keep running nevertheless and progress from one ATC program phase to the next.

To reset the simulation, cycle the Talk to us checkbox off and on. It is also reset when a new ICAO code is entered in the Origin edit field while the aircraft is on the ground.

The Talk to others mode can be active with or without the Talk to us mode selected. In Talk to others mode, random talk can be heard on those ATC channels that are currently responsible. This is indicated by the green label "Responsible now" on Instructor > Situation > Human > Voice-ATC.

If the Talk to us checkbox is off and the Talk to others checkbox is on, the responsibilities will be handed over automatically:

• If the origin airport's Ground is responsible, the responsibility will be handed over to Tower when all engines are running.
• If the origin airport's Tower is responsible, the responsibility will be handed over to Departure when the aircraft climbs above 1000 feet.
• If Departure is responsible, the responsibility will be handed over to Center when the aircraft reaches the initial cruise flight level; the reference is the value entered in the edit field Initial cruise FL on the Instructor (not the CRZ ALT entered in the FMC).

The actual handover may be delayed by some seconds; this is controlled by a random generator.

If the LNAV climb checkbox is selected and the ATC model is in the departure phase, ATC allows the crew to fly with LNAV engaged. In other words, no vectors will be given unless the active FMC leg is of a VECTORS type, or has a discontinuity, or if there's no active route at all. Likewise, the LNAV cruise checkbox refers to the cruise phase, the LNAV descent checkbox to the arrival phase.

: When the LNAV cruise checkbox is selected and the ATC model is in the cruise phase and the FMC has an active waypoint, ATC instructions are rare as only step climbs and frequency changes are instructed. Under these conditions, ATC triggers a SELCAL chime before sending an instruction. When the chime sounds, the pilot has to check the ACP and select that MIC button in which the CALL light is on. If that MIC is already selected, it need not be pressed again (the CALL light extinguishes when selecting that MIC while another MIC is selected, or by pressing the PTT when that MIC is already selected). In any case, when the SELCAL chime sounds, the pilot needs to assure that the called MIC is selected, and has to turn the volumes up and hold the PTT to inform ATC that the pilot is listening now. ATC will then transmit the new instruction. As usual, this instruction needs to be confirmed with the PTT. After that, the volume can be turned down, or another channel may be selected on the ACP. The SELCAL chime volume is controlled by the MAWEA. It does not depend on the ACP. The chime is ready when any of the receivers are tuned to the required COM frequency.

VHF as well as HF frequencies can be entered in the edit fields for the two Center stations. If the entered value exceeds the valid frequency range, the value is automatically limited. Entries lower than 118.0 are checked for the HF range 2.8 to 23.999.

PSX main network: On Instructor > Preferences > Audio activate the pair of Interphone speakers (left and right) only on one single PSX instance. If multiple PSX instances play the same sound source, undesired echoes or phasing effects will occur (this is also true for the other stereo sources like MAWEA speakers etc.). The network is not designed to play audio in phase to the millisecond.

When loading a situation file that also loads a running Talk to us mode, the ATC model will continue from the last saved point on only when the pilot has pushed the PTT. Note: The last instruction is not stored in the situation file; the Say again function will not work until a new instruction is received.

When VECTORS or a discontinuity is in the active FMC leg, the Talk to us model will give vectors no matter whether the respective LNAV climb/cruise/descent checkbox is selected or not.

Note that the model will not terminate the vectors scenario by a "Direct to ..." instruction. Instead, it will terminate it by instructing "Resume own navigation". At this point, at the latest, the crew has to move the next or the ensuing FMC waypoint up to the active FMC leg at pilot's discretion as the FMC will not sequence the VECTORS or the discontinuity automatically.

The pilot should always sequence the active waypoint manually whenever autosequencing isn't working. Autosequencing won't work when VECTORS or a discontinuity is in the active leg, or when a normal waypoint is in the active leg but the route offset caused by ATC vectors is too great to trigger the autosequencing. If the pilot doesn't sequence the active waypoint in due time, the ATC model may undesirably instruct a 180° turn back to that waypoint because the model follows more or less the FMC route even if the respective "LNAV climb/cruise/descent" checkbox is deselected.

Edit September 2022: The FMC (real FMC and PSX) now sequences the VECTORS leg automatically when the pilot engages the HDG SEL mode on the MCP.

"Fly heading 120" sounds confusingly similar to "Flight level 120". That's why real-life controllers, when working with flight levels, often construct headings ending with a "5" instead of a "0", e.g. 115 or 125. This principle is also modelled in the simulation. Unless the aircraft is in the arrival phase and below transition level, the pilot can be sure that all spoken 3-digit numbers ending with a "5" are headings.

If the pilot doesn't confirm an instruction, ATC repeats the instruction two or three times, and then ignores the pilot for a while. When ATC repeats an instruction, it may happen that the repeated instruction is not quite identical to the initial instruction, e.g the instructed heading may change while ATC is waiting for a confirmation. So, this feature is not the same as the "Say again" feature which is an exact repetition of the last instruction.

ATC phrases vary according to ICAO and non-ICAO regions. PSX applies ICAO phraseology if the ICAO code of the reference airport does not start with the letter C, K, or P.


Thanks, Hardy

Very useful information.  I'm continually amazed at how good the ATC voice is at providing a sense of 'someone is out there' even if flying solo on an un-networked PSX system.  Will add this page to my Manual and add-on doc file.



Agreed, very helpful Hardy!
Will /Chicago /USA