PSX ATC robot logic for pilot initiated arounds?

[torrence]

Hi Hardy,

I understand that the voice ATC engine in PSX isn't intended as a full AI simulation for all conditions.  Given that, it is remarkably realistic under most conditions.  I have a question about how it handles go around interactions. I think I understand the basic boxes on the Instructor ATC page for frequency of being directed to go around by ATC.  I tend to keep this checked at the low end most of the time and it randomly messes up my final just often enough to keep me on my toes. 

What I haven't figured out is exactly how it handles a pilot initiated go around.  When I do this either because I haven't got a stabilized approach on final or there's a weather cell moving in etc. I just fly the missed approach legs which are usually either a direct to holding fix or a course and Vectors type leg.  In these cases, ATC may or may not recognize what I've done and give me holding or frequency instructions.  Most of the time, I don't seem to get back into the ATC stream until I load a new RWY and approach into the FMC and then contact ATC again for a new approach.  Am I missing something or is this too complicated with the VNAV logic etc. for it to figure out what to do with me after I do a go around?  Or is there a possibility of a modification to detect when a go around has been initiated by the pilot (TOGA and/or sequencing legs on the missed approach) and then send the plane to a hold and transfer to appropriate freq (Approach?)?

Forgive me if I've missed something that's already in the system to handle this situation - I keep getting surprised by what's buried in PSX's logic. 

Cheers,
Torrence

[Hardy Heinlin]

Hi Torrence,

on initial contact with Tower you get "Cleared for approach runway xxx".

After a random pause, and if your aircraft track lies within 9° of the runway heading, you get "Continue approach, speed at your discretion".

After another random pause, and if your height is <900 ft, and you're <3 nm from the runway, and your track is within 60° of the runway heading, you get either a landing clearance or a go-around instruction, depending on the user setting and the randomizer.

After that you are in another check loop: When you are on the ground and the groundspeed is <50 kt, you get the "Contact* Ground ..." instruction. Otherwise, when you have passed the threshold and your height is >1000 ft, you get the "Contact* Approach ..." instruction and the approach procedure restarts. This decision -- Ground or Approach -- depends on groundspeed and height while you are in this check loop; it doesn't matter whether ATC wants you to land or not. It's your decision. But this particular check loop won't start before the above conditions marked in blue are true. If these conditions are never true, the ATC program will never advance. It can't advance earlier because a runway overflight above 900 ft could be part of an arrival procedure or of a circling approach.


Cheers,

|-|ardy


* In ICAO regions "Contact ...", else "Call ..."

[torrence]

Thanks for the clarification, Hardy

This makes sense.  I think my ATC 'drop outs' were probably due to my bad approaches and bailing out before <900 ft <3nm  .  To read back what I think these conditions mean - if I am on approach <900 ft and <3nm and things go pear shaped for whatever reason I can initiate a missed approach and on my climb out I'll get a "Contact Approach" sometime after passing threshold and >1000ft.

The only case this might not cover is being on approach and having bad wxr move over my approach track - I think when on voice ATC I can't request diversion or go around for weather?

Cheers,
Torrence

[Hardy Heinlin]

If you see bad weather before you change to Tower, and you are not on vectors, you can modify your route or even change to an alternate airport. The ATC robot will detect that. But once you are on Tower, you have to continue and get into those blue conditions. You just need to check the weather a minute earlier :-) If it's good it will certainly remain good until landing. The cell won't move that fast. If the approach isn't stable below 900 ft, go around.


Cheers,

|-|ardy

[Hardy Heinlin]

P.S.: Maybe I can add another condition in all Tower segments that advances the robot to the "blue" stuff whenever the TO/GA button is pressed. But then there is still the possibility of the aircraft being in level flight already so that pushing TO/GA would make no sense. In that case the robot must consider that a circling approach. I guess the TO/GA button is the only method here. Better than nothing.

[Will]

I like the TO/GA method, that makes a lot of sense. 

What about moving the gear to UP, as the cue for the case of an aircraft that is flying level?

[Hardy Heinlin]

The gear may not be down at the time of an early decision ...

[torrence]

Thanks Hardy,

I had thought about the TO/GA trigger also - if that doesn't produce some other problems it would add a realistic way to stay in the ATC logic system for more possible scenarios.  I like it.

Cheers,
Torrence