public static int GetFirstDataIndex(byte[] Data)
{
// Determine Length of FSPEC fields in bytes
int FSPEC_Length = ASTERIX.DetermineLenghtOfFSPEC(Data);
// Determine SIC/SAC Index
int SIC_Index = FSPEC_Length;
int SAC_Index = SIC_Index + 1;
return SAC_Index + 1;
}