Skip to content
View in the app

A better way to browse. Learn more.

iniBuilds Forum

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

FMGCS Problem so far

Featured Replies

Greetings, Team

Our lovely FMGCS have many function, also act as SUPER-COMPUTER for Pilots. But seems it misses some point.

  1. FMGCS CREATING WAYPOINT

FMGCS known is able to create waypoints whenever is needed to help either targeting route or to "guard" some altitude. Directly to the FPLN Page or STORED WAYPOINT. I am flying SVO-AMS today, I can't help but notice that it having some problem, like 2 samples below:

  • Sample 1: On FPLN Page is not able to create "Place-Bearing/Place-Bearing" Waypoint which identifies as PBX##, but whenever I tried to insert it on PILOT STORED WAYPOINTS, it goes funny 😂


I try inserting "ISENG" Waypoint which consist of SPL-020/FRO-350 which like this: Screenshot 2026-09-18 135340.png but stored like this ===> Screenshot 2026-09-18 135406.png

it should showing the preset P-B/P-B (or in PBD, it should show the P/B/D)

But, what makes it even funnier, it shown like this on FPLN Page ====> Screenshot 2026-09-18 135441.png waaayyy too far from the planned waypoint 😂

  • Sample 2: The "Place/Distance" which shown as PD## also need correction, from Waypoint ARTIP to SPL to make ARTIP/6 or SPL/-25 which a place along the route in between, but somehow it is showing this:

i put it AFTER ARTIP waypoint but somehow it placed AFTER SPL and not along the route, it also makes a different Bearing than the preset.
I notice this is also happening on A350, but I forgot to tell you about this.


  1. FMGCS PROBLEM DURING DESCEND-TO-APPROACH PHASE AND AFTER-GO-AROUND-TO-RE-APPROACH PHASE

  • Descend to Approach Phase

During descend phase, FCTM said that FMGCS calculates Descend Profile AT 2.5Degrees Glide Path and with decelaration of 100feet/second on Level Flight or may less during deceleration (Rule of Thumb: 1,000 feet/10 Nm on Level Flight OR 2,000-2,500 feet/10 Nm in case of decelerating, with Speed of 10 Knots/Nm on Level Flight or around 20 kt/Nm during deceleration)

ICAO Doc 4444 stating that Speed should be 250 kt below 10 000 feet, and speed 220-210 kt below 5 000 - 6 000 feet at TMA (Around 30-25 Nm from the Airport), and most of airport now are doing speed 180 kt between 12 Nm to 8 Nm and 160 kt from 8 Nm to 4 Nm. Then doing VApp until landing.


From what I notice from IniBuilds (A330/A340A/A350/A380), DECEL Pseudo-Waypoint is incorrectly simulated. Previously, FCTM-NOR-SOP stating that DECEL Pseudo-Waypoint is around 10-15Nm from Runway Threshold and it may goes further back if there's a speed constraint selected either on IAF, IF, or FAF to target speed around VApp at runway (IF NO SPEED CONSTRAINT, and may way further back if there is Speed Constraint on selected waypoint) but somehow actual Airbus' FMGCS doing Landing Flaps Config AT FAF instead of doing decelerated approach which stabilized at 1,000 ft. That is why I notice ALL IniBuilds Aircraft doesn't simulate the Decel Pseudo-Waypoint at FMGCS correctly.

For Example, I set speed on IAF (which PANS-ATM state around 10-15 Nm) at 180 kt, suddenly the Decel Pseudo-Waypoint moved forward towards FAF. And even worst at some High Altitude Approach (e.g LTFM which comes from 5,000 feet). See picture down below.

Screenshot 2026-09-19 122402.png Screenshot 2026-09-19 122340.png <<=== Both Pictures showing LTFM ILS Z Runway 35R

Actual Airbus FMGCS will move Decel P/W further back from IAF to compensate speed deceleration from Speed Control Constraint (250ktbelowFL100 or High Speed Descend) to GDot (which targeted by Magenta Dot) then targeting deceleration from GDot to IAF Selected Speed Constraint by Decel P/W.

So I can say that this is incorrectly simulated.


  • Missed Approach to Re-Approach Phase

I notice that every time I simulates Missed Approach, the Cruise Altitude is stayed on previous Target Cruise Altitude (FL350/FL390 or whatever previous Cruise Flight Phase selected). If I selected any Altitude, suddenly the speed goes >300 knots AFTER I re-direct to some waypoints and the rest of calculation of Magenta Dot, and Decel P/W IS GONE. But some cases, the Magenta Dot and Decel P/W is there but the FMGCS doesn't comply with that restriction and maintaining speed >300 knot even though I already preset 250/FL100 (or 220/FL050) and selected target speed or ATC-Managed Speed.

This also happening on A330/A340/A350, not specific on A380 Only.

Also, during the re-approach, the VSD on A350/A380 are showing like this ==> Screenshot 2026-09-18 184243.png Imagine if you are flying RNAV/RNP Approach with this 😂


  1. FMGCS Keyboard Function

if I want to insert "-" or "+" on CDU using Keyboard Function, this can not be inserted on CDU to make anything. But it is normal if I am using the CDU Keyboard.


If you guys can make corrections about this on any update, that would be great.

Thank you very much. Cheers.

HaveASafeFlight!

Edited by OxkyGThaib

Create an account or sign in to comment

Account

Navigation

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.