RB Logbook allows you to log your times both in HH:mm format and decimal format (H.d). So for example if you have a flight of 1 hour and 12 minutes, that would translate to:
You can switch between the two formats in More - Date Formatting.
Sometimes when you switch between these two options, you can observe differences in the total times calculated for your logbook. This happens more often when large datasets have been imported from other logbooks. These total times then seem to be erroneous, but in fact are not.
The reason for the discrepancy is that the decimal times are added after the conversion of minutes to decimals. Decimal times are less accurate than HH:mm times because each decimal is 6 minutes. This means that when you have 5 minutes or 1 minute intervals, the decimal time will need to be rounded. Because we want the flights in the list to match the total exactly, this results in a difference in the total times.
Let's show an example. Say we have a 1 hour and 17 minutes flight, that was entered in the logbook as 01:17. When we switch to decimal times, this will be treated as a flight of 1.3 hours. If we were to convert that decimal time back it would become 01:18. So one minute has 'appeared' that wasn't there before.
With one minute, this is not much of an issue. But with large numbers of flights, the difference can be significant (e.g. a few hours).
This is not incorrect, because when the times would have been logged as decimal times in the first place, they would also have been rounded. So the total time is still correct.
The alternative would be to add all the flights as HH:mm first and then apply decimal times. The rounding difference with H.d then will be much smaller. But if you would add all the flights making up the total, there would be an optical difference, and that is not desirable.
Therefore, we apply the rounding / conversion to decimal time to each flight. Please contact support if you have further questions.