diff --git a/src/main/blackbox/blackbox.c b/src/main/blackbox/blackbox.c
index 2365c3913..028f54c90 100644
--- a/src/main/blackbox/blackbox.c
+++ b/src/main/blackbox/blackbox.c
@@ -267,6 +267,8 @@ static struct {
     } u;
 } xmitState;
 
+static uint32_t blackboxConditionCache;
+
 static uint32_t blackboxIteration;
 static uint32_t blackboxPFrameIndex, blackboxIFrameIndex;
 
@@ -582,7 +584,7 @@ static void writeTag8_8SVB(int32_t *values, int valueCount)
     }
 }
 
-static bool testBlackboxCondition(FlightLogFieldCondition condition)
+static bool testBlackboxConditionUncached(FlightLogFieldCondition condition)
 {
     switch (condition) {
         case FLIGHT_LOG_FIELD_CONDITION_ALWAYS:
@@ -597,19 +599,10 @@ static bool testBlackboxCondition(FlightLogFieldCondition condition)
         case FLIGHT_LOG_FIELD_CONDITION_AT_LEAST_MOTORS_7:
         case FLIGHT_LOG_FIELD_CONDITION_AT_LEAST_MOTORS_8:
             return motorCount >= condition - FLIGHT_LOG_FIELD_CONDITION_AT_LEAST_MOTORS_1 + 1;
+        
         case FLIGHT_LOG_FIELD_CONDITION_TRICOPTER:
             return masterConfig.mixerMode == MIXER_TRI;
 
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_0:
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_1:
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_2:
-            return currentProfile->pidProfile.P8[condition - FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_0] != 0;
-
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_0:
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_1:
-        case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_2:
-            return currentProfile->pidProfile.I8[condition - FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_0] != 0;
-
         case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_0:
         case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_1:
         case FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_2:
@@ -639,6 +632,23 @@ static bool testBlackboxCondition(FlightLogFieldCondition condition)
     }
 }
 
+static void blackboxBuildConditionCache()
+{
+    FlightLogFieldCondition cond;
+
+    blackboxConditionCache = 0;
+
+    for (cond = FLIGHT_LOG_FIELD_CONDITION_FIRST; cond <= FLIGHT_LOG_FIELD_CONDITION_LAST; cond++) {
+        if (testBlackboxConditionUncached(cond))
+            blackboxConditionCache |= 1 << cond;
+    }
+}
+
+static bool testBlackboxCondition(FlightLogFieldCondition condition)
+{
+    return (blackboxConditionCache & (1 << condition)) != 0;
+}
+
 static void blackboxSetState(BlackboxState newState)
 {
     //Perform initial setup required for the new state
@@ -908,6 +918,13 @@ void startBlackbox(void)
 
         //No need to clear the content of blackboxHistoryRing since our first frame will be an intra which overwrites it
 
+        /*
+         * We use conditional tests to decide whether or not certain fields should be logged. Since our headers
+         * must always agree with the logged data, the results of these tests must not change during logging. So
+         * cache those now.
+         */
+        blackboxBuildConditionCache();
+
         blackboxSetState(BLACKBOX_STATE_SEND_HEADER);
     }
 }
diff --git a/src/main/blackbox/blackbox_fielddefs.h b/src/main/blackbox/blackbox_fielddefs.h
index 87db8ecbb..176356109 100644
--- a/src/main/blackbox/blackbox_fielddefs.h
+++ b/src/main/blackbox/blackbox_fielddefs.h
@@ -29,21 +29,18 @@ typedef enum FlightLogFieldCondition {
     FLIGHT_LOG_FIELD_CONDITION_AT_LEAST_MOTORS_8,
     FLIGHT_LOG_FIELD_CONDITION_TRICOPTER,
 
-    FLIGHT_LOG_FIELD_CONDITION_MAG = 20,
+    FLIGHT_LOG_FIELD_CONDITION_MAG,
     FLIGHT_LOG_FIELD_CONDITION_BARO,
     FLIGHT_LOG_FIELD_CONDITION_VBAT,
 
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_0 = 40,
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_1,
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_P_2,
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_0,
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_1,
-    FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_I_2,
     FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_0,
     FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_1,
     FLIGHT_LOG_FIELD_CONDITION_NONZERO_PID_D_2,
 
-    FLIGHT_LOG_FIELD_CONDITION_NEVER = 255,
+    FLIGHT_LOG_FIELD_CONDITION_NEVER,
+
+    FLIGHT_LOG_FIELD_CONDITION_FIRST = FLIGHT_LOG_FIELD_CONDITION_ALWAYS,
+    FLIGHT_LOG_FIELD_CONDITION_LAST = FLIGHT_LOG_FIELD_CONDITION_NEVER
 } FlightLogFieldCondition;
 
 typedef enum FlightLogFieldPredictor {