diff --git a/.github/CHANGELOG.md b/.github/CHANGELOG.md
index c3e36e82dfd..affacd06b5f 100644
--- a/.github/CHANGELOG.md
+++ b/.github/CHANGELOG.md
@@ -86,6 +86,7 @@
 1. [A380X/FWS] Fix "NO ZFW OR ZFWCG DATA" ECAM alert after landing - @flogross89 (floridude)
 1. [A380X/SD] Add brake temperature color change to amber when brakes are hot - @heclak (Heclak)
 1. [A380X/FCU] Fix display of values on FCU during light test - @heclak (Heclak)
+1. [A380X/FMS] Fix VLS computation error for CONF 1, might have lead to FMS crashes during climb out - @flogross89 (floridude)
 
 ## 0.12.0
 
diff --git a/fbw-a380x/src/systems/instruments/src/MFD/FMC/FmcAircraftInterface.ts b/fbw-a380x/src/systems/instruments/src/MFD/FMC/FmcAircraftInterface.ts
index 77bbe6f40b8..e2d1092e4d3 100644
--- a/fbw-a380x/src/systems/instruments/src/MFD/FMC/FmcAircraftInterface.ts
+++ b/fbw-a380x/src/systems/instruments/src/MFD/FMC/FmcAircraftInterface.ts
@@ -1116,7 +1116,7 @@ export class FmcAircraftInterface {
     const altActive = false;
     const landingWeight =
       this.fmgc.data.zeroFuelWeight.get() ??
-      NaN + (altActive ? this.fmgc.getAltEFOB(true) : this.fmgc.getDestEFOB(true));
+      NaN + (altActive ? this.fmgc.getAltEFOB(true) : this.fmgc.getDestEFOB(true)) * 1_000;
 
     return Number.isFinite(landingWeight) ? landingWeight : NaN;
   }
@@ -1128,7 +1128,7 @@ export class FmcAircraftInterface {
     /** in kg */
     const estLdgWeight = this.tryEstimateLandingWeight();
     let ldgWeight = estLdgWeight;
-    const grossWeight = this.fmc.fmgc.getGrossWeightKg() ?? maxZfw + this.fmc.fmgc.getFOB();
+    const grossWeight = this.fmc.fmgc.getGrossWeightKg() ?? maxZfw + this.fmc.fmgc.getFOB() * 1_000;
     const vnavPrediction = this.fmc.guidanceController?.vnavDriver?.getDestinationPrediction();
     // Actual weight is used during approach phase (FCOM bulletin 46/2), and we also assume during go-around
     if (this.flightPhase.get() >= FmgcFlightPhase.Approach || !Number.isFinite(estLdgWeight)) {
@@ -1178,14 +1178,10 @@ export class FmcAircraftInterface {
       // Only update speeds if ADR data valid
 
       const flapLever = SimVar.GetSimVarValue('L:A32NX_FLAPS_HANDLE_INDEX', 'Enum');
-      let flaps = flapLever;
-      if (flapLever === 1 && SimVar.GetSimVarValue('L:A32NX_FLAPS_CONF_INDEX', 'Enum') === 1) {
-        flaps = 5; // CONF 1
-      }
       const speeds = new A380OperatingSpeeds(
         grossWeight,
         cas,
-        flaps,
+        flapLever,
         this.flightPhase.get(),
         this.fmgc.getV2Speed(),
         alt,
@@ -1199,10 +1195,10 @@ export class FmcAircraftInterface {
         const f = Math.max(speeds.f2, Vmcl + 5);
         this.fmgc.data.flapRetractionSpeed.set(Math.ceil(f));
       } else {
-        if (flaps === 2) {
+        if (flapLever === 2) {
           const f = Math.max(speeds.f2, Vmcl + 15);
           this.fmgc.data.flapRetractionSpeed.set(Math.ceil(f));
-        } else if (flaps === 3) {
+        } else if (flapLever === 3) {
           const f = Math.max(speeds.f3, Vmcl + 10);
           this.fmgc.data.flapRetractionSpeed.set(Math.ceil(f));
         }
diff --git a/fbw-a380x/src/systems/instruments/src/MFD/FMC/fmgc.ts b/fbw-a380x/src/systems/instruments/src/MFD/FMC/fmgc.ts
index 713250cdafe..9b7b741d070 100644
--- a/fbw-a380x/src/systems/instruments/src/MFD/FMC/fmgc.ts
+++ b/fbw-a380x/src/systems/instruments/src/MFD/FMC/fmgc.ts
@@ -564,7 +564,7 @@ export class FmgcDataService implements Fmgc {
     return this.data.approachTemperature.get() ?? 0;
   }
 
-  /** in kilograms */
+  /** in tons */
   getDestEFOB(useFob: boolean): number {
     // Metric tons
     const efob = this.guidanceController?.vnavDriver?.getDestinationPrediction()?.estimatedFuelOnBoard; // in Pounds
@@ -574,7 +574,7 @@ export class FmgcDataService implements Fmgc {
     return 0;
   }
 
-  /** in kilograms */
+  /** in tons */
   getAltEFOB(useFOB = false): number {
     // TODO estimate alternate fuel
     if (this.getDestEFOB(useFOB) === 0) {
diff --git a/fbw-a380x/src/systems/shared/src/OperatingSpeeds.tsx b/fbw-a380x/src/systems/shared/src/OperatingSpeeds.tsx
index d5d9974aaf6..f5fcd90d7c3 100644
--- a/fbw-a380x/src/systems/shared/src/OperatingSpeeds.tsx
+++ b/fbw-a380x/src/systems/shared/src/OperatingSpeeds.tsx
@@ -119,6 +119,9 @@ export class SpeedsLookupTables {
     if (conf === 0) {
       return SpeedsLookupTables.VLS_CONF_0.get(0, weight);
     } else {
+      if (conf > 5) {
+        throw new Error('Invalid flap config for approach VLS computation');
+      }
       return SpeedsLookupTables.VLS_APPR_CONF[conf].get(cg, weight);
     }
   }
@@ -512,13 +515,12 @@ export class A380OperatingSpeeds {
     this.f2 =
       fmgcFlightPhase <= FmgcFlightPhase.Takeoff
         ? Math.max(1.18 * vs1gConf1F, Vmcl + 5)
-        : SpeedsLookupTables.F2_SPEED.get(altitude, m);
+        : SpeedsLookupTables.F2_SPEED.get(cg, m);
     this.f3 =
       fmgcFlightPhase <= FmgcFlightPhase.Takeoff
         ? Math.max(1.18 * vs1gConf1F, Vmcl + 5)
-        : SpeedsLookupTables.F3_SPEED.get(altitude, m);
-    this.s =
-      fmgcFlightPhase <= FmgcFlightPhase.Takeoff ? 1.21 * vs1gConf0 : SpeedsLookupTables.S_SPEED.get(altitude, m);
+        : SpeedsLookupTables.F3_SPEED.get(cg, m);
+    this.s = fmgcFlightPhase <= FmgcFlightPhase.Takeoff ? 1.21 * vs1gConf0 : SpeedsLookupTables.S_SPEED.get(m);
   }
 }