diff --git a/calcs/cpa_tcpa.js b/calcs/cpa_tcpa.js
index f96a8fb..a1f4815 100755
--- a/calcs/cpa_tcpa.js
+++ b/calcs/cpa_tcpa.js
@@ -6,6 +6,29 @@ var alarmSent = []
 var notificationLevels = ['normal', 'alert', 'warn', 'alarm', 'emergency']
 
 module.exports = function (app, plugin) {
+
+  const secondsSinceVesselUpdate = (vessel, path) => {
+    const _vesselTimestamp = app.getPath(
+      'vessels.' + vessel + '.' + path
+    )
+    if (!_vesselTimestamp) {
+      return Date.now() / 1000
+    }
+    const vesselTimestamp = new Date(_vesselTimestamp).getTime()
+
+    let currentTime
+    const currentTimeString = app.getSelfPath('navigation.datetime.value')
+    if (currentTimeString) {
+      currentTime = new Date(currentTimeString).getTime()
+    } else {
+      currentTime = Date.now()
+    }
+
+    return Math.floor(
+      (currentTime - vesselTimestamp) / 1e3
+    )
+  }
+
   return {
     group: 'traffic',
     optionKey: 'CPA',
@@ -116,6 +139,27 @@ module.exports = function (app, plugin) {
         if (typeof vessel === 'undefined' || vessel == app.selfId) {
           continue
         }
+
+        if (secondsSinceVesselUpdate(vessel, 'navigation.position.timestamp') > plugin.properties.traffic.timelimit) {
+          app.debug('old position of vessel, not calculating')
+          if (app.getPath(
+            'vessels.' + vessel + '.navigation.distanceToSelf.value'
+          ) !== null) {
+            deltas.push({
+              context: 'vessels.' + vessel,
+              updates: [
+                {
+                  values: [CPA_TCPA(null, null), {
+                    path: 'navigation.distanceToSelf',
+                    value: null
+                  }]
+                }
+              ]
+            })
+          }
+          continue
+        } // old data from vessel, not calculating
+
         var vesselPos = app.getPath(
           'vessels.' + vessel + '.navigation.position.value'
         )
@@ -155,27 +199,6 @@ module.exports = function (app, plugin) {
             continue
           } // if distance outside range, don't calculate
 
-          var vesselTimestamp = app.getPath(
-            'vessels.' + vessel + '.navigation.position.timestamp'
-          )
-          vesselTimestamp = new Date(vesselTimestamp).getTime()
-
-          var currentTime
-          var currentTimeString = app.getSelfPath('navigation.datetime.value')
-          if (currentTimeString) {
-            currentTime = new Date(currentTimeString).getTime()
-          } else {
-            currentTime = Date.now()
-          }
-
-          var secondsSinceVesselUpdate = Math.floor(
-            (currentTime - vesselTimestamp) / 1e3
-          )
-          if (secondsSinceVesselUpdate > plugin.properties.traffic.timelimit) {
-            app.debug('old data from vessel, not calculating')
-            continue
-          } // old data from vessel, not calculating
-
           var vesselCourse = app.getPath(
             'vessels.' + vessel + '.navigation.courseOverGroundTrue.value'
           )
@@ -183,6 +206,21 @@ module.exports = function (app, plugin) {
             'vessels.' + vessel + '.navigation.speedOverGround.value'
           )
 
+          if (secondsSinceVesselUpdate(vessel, 'navigation.courseOverGroundTrue') > plugin.properties.traffic.timelimit || 
+              secondsSinceVesselUpdate(vessel, 'navigation.speedOverGround') > plugin.properties.traffic.timelimit) {
+            app.debug('old course data from vessel, not calculating CPA')
+            if (vesselCourse !== null || vesselSpeed !== null) {
+              deltas.push({
+                context: 'vessels.' + vessel,
+                updates: [
+                  {
+                    values: [CPA_TCPA(null, null)]
+                  }
+                ]
+              })
+            }
+            continue
+          }
           if (!_.isUndefined(vesselCourse) && !_.isUndefined(vesselSpeed)) {
             var vesselCourseDeg = geoutils.radToDeg(vesselCourse)
             var otherVessel = {