diff --git a/etc/qc/default/definitions.yaml b/etc/qc/default/definitions.yaml
index b165601..8f637c7 100644
--- a/etc/qc/default/definitions.yaml
+++ b/etc/qc/default/definitions.yaml
@@ -122,6 +122,37 @@
                             true;
                         }
 
+                -
+                    name: "Synchronisation (warning)"
+                    check: |
+                        const currentShot = currentItem;
+                        const gunData = currentShot._("raw_meta.smsrc");
+                        let result = [];
+                        if (gunData && gunData.num_nofire == 0) {
+
+                            // These are the indices into the gun array for the different
+                            // values of interest.
+                            const subarray = 0;
+                            const aimpoint = 7;
+                            const firetime = 8;
+
+                            // We only care about the source which actually fired (or was supposed to)
+                            const sourceFired = gunData.guns.filter(g => g[2] == gunData.src_number);
+
+                            sourceFired
+                            .filter(gun => Math.abs(gun[firetime]-gun[aimpoint]) >= parameters.gunTimingWarning && Math.abs(gun[firetime]-gun[aimpoint]) <= parameters.gunTiming)
+                            .forEach(gun => {
+                                const value = Math.abs(gun[firetime]-gun[aimpoint]);
+                                result.push(`Delta error: source ${gun[2]}, string ${gun[0]}, gun ${gun[1]}: ${parameters.gunTimingWarning} ≤ ${value.toFixed(2)} ≤ ${parameters.gunTimingWarning}`);
+                            });
+                        }
+                        if (result.length) {
+                            result.join("; ");
+                        } else {
+                            // Either there were no error or gun data was missing, which we take care of elsewhere
+                            true;
+                        }
+
                 -
                     name: "Autofire"
                     check: |
diff --git a/etc/qc/default/parameters.yaml b/etc/qc/default/parameters.yaml
index f5ec194..78d843c 100644
--- a/etc/qc/default/parameters.yaml
+++ b/etc/qc/default/parameters.yaml
@@ -1,6 +1,7 @@
 
 gunDepth: 6.0
 gunDepthTolerance: 0.5
+gunTimingWarning: 1.0
 gunTiming: 1.5
 gunTimingSubarrayAverage: 0.5
 gunPressureNominal: 2000