diff --git a/libraries/DataFlash/DataFlash.cpp b/libraries/DataFlash/DataFlash.cpp
index 0e6475e785..8ddfe6edb9 100644
--- a/libraries/DataFlash/DataFlash.cpp
+++ b/libraries/DataFlash/DataFlash.cpp
@@ -66,5 +66,11 @@ void DataFlash_Class::EnableWrites(bool enable) {
     backend->EnableWrites(enable);
 }
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    // currently only DataFlash_File support this:
+void DataFlash_Class::flush(void) {
+    backend->flush();
+}
+#endif
 
 // end functions pass straight through to backend
diff --git a/libraries/DataFlash/DataFlash.h b/libraries/DataFlash/DataFlash.h
index 1dd1bf51a7..55753fc817 100644
--- a/libraries/DataFlash/DataFlash.h
+++ b/libraries/DataFlash/DataFlash.h
@@ -104,6 +104,11 @@ public:
 
     bool logging_started(void);
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    // currently only DataFlash_File support this:
+    void flush(void);
+#endif
+
 protected:
     void Log_Fill_Format(const struct LogStructure *structure, struct log_Format &pkt);
     void Log_Write_Parameter(const AP_Param *ap, const AP_Param::ParamToken &token, 
diff --git a/libraries/DataFlash/DataFlash_Backend.h b/libraries/DataFlash/DataFlash_Backend.h
index 35588a6261..5f384e9317 100644
--- a/libraries/DataFlash/DataFlash_Backend.h
+++ b/libraries/DataFlash/DataFlash_Backend.h
@@ -68,6 +68,11 @@ public:
 
     void Log_Fill_Format(const struct LogStructure *structure, struct log_Format &pkt);
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    // currently only DataFlash_File support this:
+    virtual void flush(void) { }
+#endif
+
 protected:
     DataFlash_Class &_front;
 
diff --git a/libraries/DataFlash/DataFlash_File.cpp b/libraries/DataFlash/DataFlash_File.cpp
index 653746e164..9134ada8ec 100644
--- a/libraries/DataFlash/DataFlash_File.cpp
+++ b/libraries/DataFlash/DataFlash_File.cpp
@@ -608,6 +608,25 @@ void DataFlash_File::ListAvailableLogs(AP_HAL::BetterStream *port)
     port->println();    
 }
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+void DataFlash_File::flush(void)
+{
+    uint16_t _tail;
+    uint32_t tnow = hal.scheduler->micros();
+    hal.scheduler->suspend_timer_procs();
+    while (_write_fd != -1 && _initialised && !_open_error &&
+           BUF_AVAILABLE(_writebuf)) {
+        // convince the IO timer that it really is OK to write out
+        // less than _writebuf_chunk bytes:
+        _last_write_time = tnow - 2000000;
+        _io_timer();
+    }
+    hal.scheduler->resume_timer_procs();
+    if (_write_fd != -1) {
+        ::fsync(_write_fd);
+    }
+}
+#endif
 
 void DataFlash_File::_io_timer(void)
 {
diff --git a/libraries/DataFlash/DataFlash_File.h b/libraries/DataFlash/DataFlash_File.h
index 438aea8909..6bd2521190 100644
--- a/libraries/DataFlash/DataFlash_File.h
+++ b/libraries/DataFlash/DataFlash_File.h
@@ -53,6 +53,10 @@ public:
     void ShowDeviceInfo(AP_HAL::BetterStream *port);
     void ListAvailableLogs(AP_HAL::BetterStream *port);
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    void flush(void);
+#endif
+
 private:
     int _write_fd;
     int _read_fd;