FMC - Overriding speed/ in legs page - Causes LUA script error

[Splash]

Reporting bug (running latest version):

Create any flight plan and finish programming the FMC. Then go to legs page and try to change "speed only" on any of the legs by typing the desired speed (ex: 200/) and pressing line select key. When I try to do that Gizmo console comes up with an error line:

 

Callback_Dref_Hooked_setDataf: cdul_lsk 4R onWrite: [string "ixeg.733.fmc.legs.lua.ral"]:950:attempt to index local 'altInput' (a boolean value)

If I am required to type in 200/5000 (speed/alt) instead of just speed shouldn't the FMC display invalid entry?

Btw, the value ends up in the FMC (I can see it displayed) but the line select key stops working (ie. clicking this LSK results in no response until you reload lua scripts probably because of the error).

Attached is screenshot of the error.

 

Edited December 15, 2020 by Splash

[Litjan]

Hi Splash,

you are right, once the lua error screen comes up, the rest of the code is on shaky ground and may be erroneous, a reboot of Gizmo is the only way out.

I am sorry that you had this error, while speed and altitude inputs in the LEGS page are not being honored by our VNAV code right now, at least they should not cause a lua error!

So to save yourself the trouble and potential lua error, for now I would refrain from editing the route heavily with constraints. At best this could serve as a reminder for you, but the VNAV code will not attempt to meet your restrictions.

If restrictions are read from the database, you can leave those untouched, of course.

Cheers, Jan

 

[Splash]

No worries, ... Just a question in regards to changing speed from what is setup in the FMC. For example, I would like to fly slower what's on the legs page as I approach my destination to give myself more time to setup the aircraft for landing. One option is to just get out of VNAV and use MCP speed but what about changing the speed in FMC and still using VNAV (for descend/speed)? Is that possible right now?

If not, when do you think it will be possible to change speed restrictions in FMC and have VNAV follow these modified speeds?

 

Edited December 16, 2020 by Splash

[Litjan]

Currently this is possible "sometimes" . In my experience the VNAV code obeys speed limits inherent in the procedure quite well, and it will probably also adhere to manual changes...but you should do them as early as possible (ideally before taking off). The current VNAV code does not react very well to changes made during the flight.

A workaround would be to disengage the autothrust (turn if off completely) and use the thrust levers to manage your speed manually - VNAV would still follow the path.

Naturally we hope to fix all that in the future...

Cheers, Jan

 

Edited December 16, 2020 by Litjan

[Splash]

Sweet, thanks Jan.