diff --git a/main/format.cpp b/main/format.cpp
index 8f6ca20..98aa6ef 100644
--- a/main/format.cpp
+++ b/main/format.cpp
@@ -76,6 +76,10 @@ void Format_Hex( void (*Output)(char), uint32_t Word )
 { Format_Hex(Output, (uint8_t)(Word>>24)); Format_Hex(Output, (uint8_t)(Word>>16));
   Format_Hex(Output, (uint8_t)(Word>>8));  Format_Hex(Output, (uint8_t)Word); }
 
+void Format_Hex( void (*Output)(char), uint64_t Word )
+{ Format_Hex(Output, (uint32_t)(Word>>32));
+  Format_Hex(Output, (uint32_t)(Word    )); }
+
 void Format_MAC( void (*Output)(char), uint8_t *MAC, uint8_t Len)
 { for(uint8_t Idx=0; Idx<Len; Idx++)
   { if(Idx) (*Output)(':');
@@ -284,11 +288,16 @@ int16_t Read_Dec3(const char *Inp)             // convert three digit decimal nu
   int8_t Low=Read_Dec1(Inp[2]);  if(Low<0) return -1;
   return (int16_t)Low + (int16_t)10*(int16_t)Mid + (int16_t)100*(int16_t)High; }
 
-int16_t Read_Dec4(const char *Inp)             // convert three digit decimal number into an integer
+int16_t Read_Dec4(const char *Inp)             // convert four digit decimal number into an integer
 { int16_t High=Read_Dec2(Inp  ); if(High<0) return -1;
   int16_t Low =Read_Dec2(Inp+2); if(Low<0) return -1;
   return Low + (int16_t)100*(int16_t)High; }
 
+int32_t Read_Dec5(const char *Inp)             // convert four digit decimal number into an integer
+{ int16_t High=Read_Dec2(Inp  ); if(High<0) return -1;
+  int16_t Low =Read_Dec3(Inp+2); if(Low<0) return -1;
+  return (int32_t)Low + (int32_t)1000*(int32_t)High; }
+
 // ------------------------------------------------------------------------------------------
 
 int8_t Read_Coord(int32_t &Lat, const char *Inp)
diff --git a/main/format.h b/main/format.h
index 4d135ec..f0c3ad1 100644
--- a/main/format.h
+++ b/main/format.h
@@ -16,6 +16,7 @@ void Format_String( void (*Output)(char), const    char *String, uint8_t MinLen,
 void Format_Hex( void (*Output)(char), uint8_t  Byte );
 void Format_Hex( void (*Output)(char), uint16_t Word );
 void Format_Hex( void (*Output)(char), uint32_t Word );
+void Format_Hex( void (*Output)(char), uint64_t Word );
 // void Format_Hex( void (*Output)(char), uint32_t Word, uint8_t Digits);
 void Format_MAC( void (*Output)(char), const uint8_t *MAC, uint8_t Len=6);
 
@@ -78,7 +79,8 @@ int8_t  Read_Dec1(char Digit);                  // convert single digit into an
 inline int8_t Read_Dec1(const char *Inp) { return Read_Dec1(Inp[0]); }
 int8_t  Read_Dec2(const char *Inp);             // convert two digit decimal number into an integer
 int16_t Read_Dec3(const char *Inp);             // convert three digit decimal number into an integer
-int16_t Read_Dec4(const char *Inp);             // convert three digit decimal number into an integer
+int16_t Read_Dec4(const char *Inp);             // convert four digit decimal number into an integer
+int32_t Read_Dec5(const char *Inp);             // convert five digit decimal number into an integer
 
   template <class Type>
    int8_t Read_Hex(Type &Int, const char *Inp, uint8_t MaxDig=0) // convert variable number of digits hexadecimal number into an integer
@@ -120,7 +122,8 @@ template <class Type>
    { Dig=Read_UnsDec(Value, Inp+Len); }
    if(Dig<=0) return Dig;
    Len+=Dig;
-   if(Sign=='-') Value=(-Value); return Len; }
+   if(Sign=='-') Value=(-Value);
+   return Len; }
 
 template <class Type>
  int8_t Read_Float1(Type &Value, const char *Inp)       // read floating point, take just one digit after decimal point
diff --git a/main/sdlog.cpp b/main/sdlog.cpp
index de55683..4630452 100644
--- a/main/sdlog.cpp
+++ b/main/sdlog.cpp
@@ -125,7 +125,8 @@ static void IGC_Close(void)
     Format_String(CONS_UART_Write, IGC_FileName);
     Format_String(CONS_UART_Write, "\n");
     xSemaphoreGive(CONS_Mutex);
-    fclose(IGC_File); IGC_File=0; IGC_FlightNum++; }
+    fclose(IGC_File); IGC_File=0;
+    IGC_FlightNum++; }
 }
 /*
     IGC_SaveTime = TimeSync_Time();
@@ -146,11 +147,14 @@ static int IGC_Open(const GPS_Position &GPS)
   IGC_FileName[IGC_PathLen]='/';                                    // slash after the path
   Flight.ShortName(IGC_FileName+IGC_PathLen+1, GPS, IGC_FlightNum, IGC_Serial); // full name
   IGC_File=fopen(IGC_FileName, "rt");                               // attempt to open for read, just to try if the file is already there
-  if(IGC_File) { IGC_Close(); return -2; }                          // -2 => file already exists
+  // Format_String(CONS_UART_Write, "IGC_Open() (1)\n");
+  if(IGC_File) { fclose(IGC_File); IGC_File=0; IGC_FlightNum++; return -2; } // -2 => file already exists
   IGC_File=fopen(IGC_FileName, "wt");                               // open for write
+  // Format_String(CONS_UART_Write, "IGC_Open() (2)\n");
   if(IGC_File==0)                                                   // failed: maybe sub-dir does not exist ?
   { if(mkdir(IGC_Path, 0777)<0) return -3;                          // -3 => can't create sub-dir
     IGC_File=fopen(IGC_FileName, "wt"); }                           // retry to open for write
+  // Format_String(CONS_UART_Write, "IGC_Open() (3)\n");
   if(IGC_File)
   { IGC_SaveTime = TimeSync_Time();
     xSemaphoreTake(CONS_Mutex, portMAX_DELAY);
@@ -368,13 +372,13 @@ static void IGC_CheckGPS(void)                                   // check if new
 { static uint8_t PrevPosIdx=0;
   if(GPS_PosIdx==PrevPosIdx) return;
   PrevPosIdx=GPS_PosIdx;
-  const  uint8_t PosPipeIdxMask = GPS_PosPipeSize-1;                 // get the GPS position just before in the pipe
+  const  uint8_t PosPipeIdxMask = GPS_PosPipeSize-1;             // get the GPS position just before in the pipe
   uint8_t PosIdx = GPS_PosIdx-1; PosIdx&=PosPipeIdxMask;
   static bool PrevInFlight=0;
   const GPS_Position &GPS = GPS_Pos[PosIdx];
-  bool inFlight = GPS.InFlight;                                      // in-flight or on-the-ground ?
-  bool StopFile = PrevInFlight && !inFlight;
-  PrevInFlight = inFlight;;
+  bool inFlight = GPS.InFlight;                                  // in-flight or on-the-ground ?
+  bool StopFile = PrevInFlight && !inFlight;                     // decide to stop the file when InFlight switches from 1 to 0
+  PrevInFlight = inFlight;
 #ifdef DEBUG_PRINT
   GPS.PrintLine(Line);
   xSemaphoreTake(CONS_Mutex, portMAX_DELAY);