diff --git a/src/main/blackbox/blackbox.c b/src/main/blackbox/blackbox.c
index 33fe7f08c3..3fd7cbf638 100644
--- a/src/main/blackbox/blackbox.c
+++ b/src/main/blackbox/blackbox.c
@@ -42,17 +42,13 @@
 #include "common/time.h"
 #include "common/utils.h"
 
+#include "config/config.h"
 #include "config/feature.h"
-#include "pg/pg.h"
-#include "pg/pg_ids.h"
-#include "pg/motor.h"
-#include "pg/rx.h"
 
 #include "drivers/compass/compass.h"
 #include "drivers/sensor.h"
 #include "drivers/time.h"
 
-#include "config/config.h"
 #include "fc/board_info.h"
 #include "fc/controlrate_profile.h"
 #include "fc/rc.h"
@@ -70,6 +66,11 @@
 #include "io/gps.h"
 #include "io/serial.h"
 
+#include "pg/pg.h"
+#include "pg/pg_ids.h"
+#include "pg/motor.h"
+#include "pg/rx.h"
+
 #include "rx/rx.h"
 
 #include "sensors/acceleration.h"
@@ -281,6 +282,7 @@ typedef enum BlackboxState {
     BLACKBOX_STATE_SEND_GPS_G_HEADER,
     BLACKBOX_STATE_SEND_SLOW_HEADER,
     BLACKBOX_STATE_SEND_SYSINFO,
+    BLACKBOX_STATE_CACHE_FLUSH,
     BLACKBOX_STATE_PAUSED,
     BLACKBOX_STATE_RUNNING,
     BLACKBOX_STATE_SHUTTING_DOWN,
@@ -1607,6 +1609,8 @@ STATIC_UNIT_TESTED void blackboxLogIteration(timeUs_t currentTimeUs)
  */
 void blackboxUpdate(timeUs_t currentTimeUs)
 {
+    static BlackboxState cacheFlushNextState;
+
     switch (blackboxState) {
     case BLACKBOX_STATE_STOPPED:
         if (ARMING_FLAG(ARMED)) {
@@ -1680,7 +1684,8 @@ void blackboxUpdate(timeUs_t currentTimeUs)
         //On entry of this state, xmitState.headerIndex is 0 and xmitState.u.fieldIndex is -1
         if (!sendFieldDefinition('S', 0, blackboxSlowFields, blackboxSlowFields + 1, ARRAYLEN(blackboxSlowFields),
                 NULL, NULL)) {
-            blackboxSetState(BLACKBOX_STATE_SEND_SYSINFO);
+            cacheFlushNextState = BLACKBOX_STATE_SEND_SYSINFO;
+            blackboxSetState(BLACKBOX_STATE_CACHE_FLUSH);
         }
         break;
     case BLACKBOX_STATE_SEND_SYSINFO:
@@ -1694,9 +1699,14 @@ void blackboxUpdate(timeUs_t currentTimeUs)
              * (overflowing circular buffers causes all data to be discarded, so the first few logged iterations
              * could wipe out the end of the header if we weren't careful)
              */
-            if (blackboxDeviceFlushForce()) {
-                blackboxSetState(BLACKBOX_STATE_RUNNING);
-            }
+            cacheFlushNextState = BLACKBOX_STATE_RUNNING;
+            blackboxSetState(BLACKBOX_STATE_CACHE_FLUSH);
+        }
+        break;
+    case BLACKBOX_STATE_CACHE_FLUSH:
+        // Flush the cache and wait until all possible entries have been written to the media
+        if (blackboxDeviceFlushForceComplete()) {
+            blackboxSetState(cacheFlushNextState);
         }
         break;
     case BLACKBOX_STATE_PAUSED:
diff --git a/src/main/blackbox/blackbox_io.c b/src/main/blackbox/blackbox_io.c
index da8886475d..b3515091bb 100644
--- a/src/main/blackbox/blackbox_io.c
+++ b/src/main/blackbox/blackbox_io.c
@@ -242,9 +242,11 @@ bool blackboxDeviceFlushForce(void)
 
 #ifdef USE_SDCARD
     case BLACKBOX_DEVICE_SDCARD:
-        /* SD card will flush itself without us calling it, but we need to call flush manually in order to check
-         * if it's done yet or not!
-         */
+        // SD card will flush itself without us calling it, but we need to call flush manually in order to check
+        // if it's done yet or not!
+        // However the "flush" only queues one dirty sector each time and the process is asynchronous. So after
+        // the last dirty sector is queued the flush returns true even though the sector may not actually have
+        // been physically written to the SD card yet.
         return afatfs_flush();
 #endif // USE_SDCARD
 
@@ -253,6 +255,26 @@ bool blackboxDeviceFlushForce(void)
     }
 }
 
+// Flush the blackbox device and only return true if sync is actually complete.
+// Primarily to ensure the async operations of SD card sector writes complete thus freeing the cache entries.
+bool blackboxDeviceFlushForceComplete(void)
+{
+    switch (blackboxConfig()->device) {
+#ifdef USE_SDCARD
+    case BLACKBOX_DEVICE_SDCARD:
+        if (afatfs_sectorCacheInSync()) {
+            return true;
+        } else {
+            blackboxDeviceFlushForce();
+            return false;
+        }
+#endif // USE_SDCARD
+
+    default:
+        return blackboxDeviceFlushForce();
+    }
+}
+
 /**
  * Attempt to open the logging device. Returns true if successful.
  */
diff --git a/src/main/blackbox/blackbox_io.h b/src/main/blackbox/blackbox_io.h
index 52af9d5d2f..ba3ec1cc18 100644
--- a/src/main/blackbox/blackbox_io.h
+++ b/src/main/blackbox/blackbox_io.h
@@ -46,6 +46,8 @@ int blackboxWriteString(const char *s);
 
 void blackboxDeviceFlush(void);
 bool blackboxDeviceFlushForce(void);
+bool blackboxDeviceFlushForceComplete(void);
+
 bool blackboxDeviceOpen(void);
 void blackboxDeviceClose(void);
 
diff --git a/src/main/io/asyncfatfs/asyncfatfs.c b/src/main/io/asyncfatfs/asyncfatfs.c
index 871ad1382e..3b4b2db9e8 100644
--- a/src/main/io/asyncfatfs/asyncfatfs.c
+++ b/src/main/io/asyncfatfs/asyncfatfs.c
@@ -44,21 +44,23 @@
 #include <stdio.h>
 #endif
 
-#include "asyncfatfs.h"
-
-#include "fat_standard.h"
-#include "drivers/sdcard.h"
 #include "common/maths.h"
 #include "common/time.h"
 #include "common/utils.h"
 
+#include "drivers/sdcard.h"
+
+#include "fat_standard.h"
+
+#include "asyncfatfs.h"
+
 #ifdef AFATFS_DEBUG
     #define ONLY_EXPOSE_FOR_TESTING
 #else
     #define ONLY_EXPOSE_FOR_TESTING static
 #endif
 
-#define AFATFS_NUM_CACHE_SECTORS 10
+#define AFATFS_NUM_CACHE_SECTORS 11
 
 // FAT filesystems are allowed to differ from these parameters, but we choose not to support those weird filesystems:
 #define AFATFS_SECTOR_SIZE  512
@@ -736,6 +738,18 @@ static void afatfs_cacheFlushSector(int cacheIndex)
     }
 }
 
+// Check whether every sector in the cache that can be flushed has been synchronized
+bool afatfs_sectorCacheInSync(void)
+{
+    for (int i = 0; i < AFATFS_NUM_CACHE_SECTORS; i++) {
+        if ((afatfs.cacheDescriptor[i].state == AFATFS_CACHE_STATE_WRITING) ||
+            ((afatfs.cacheDescriptor[i].state == AFATFS_CACHE_STATE_DIRTY) && !afatfs.cacheDescriptor[i].locked)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 /**
  * Find a sector in the cache which corresponds to the given physical sector index, or NULL if the sector isn't
  * cached. Note that the cached sector could be in any state including completely empty.
diff --git a/src/main/io/asyncfatfs/asyncfatfs.h b/src/main/io/asyncfatfs/asyncfatfs.h
index 99750f1e66..67906719e2 100644
--- a/src/main/io/asyncfatfs/asyncfatfs.h
+++ b/src/main/io/asyncfatfs/asyncfatfs.h
@@ -93,3 +93,4 @@ bool afatfs_isFull(void);
 
 afatfsFilesystemState_e afatfs_getFilesystemState(void);
 afatfsError_e afatfs_getLastError(void);
+bool afatfs_sectorCacheInSync(void);