I just played GameID=816929
and I thought I could safely retire without honour (I had no fuel and a good distance from home) and we would win a tactical victory - i was wrong

the rules are not completely clear
If, at the end of the game, there is more than one side remaining on the board, the victory could be tactical. This happens when the number of enemies destroyed is percentually more relevant than the unit lost.
E.g. Suppose the leagues is based on a 4 vs. 3 scenario. If at the end of a game there are still 3 units of side A and 2 unit of side B, then the side A achieve a tactical victory since side B has suffered a numer of loss percentually higher than side A. On the other side, if the game ends with only 1 unit still on board for each side, than the winner is side B, since thay have lost onyl 66% of their units, while side A have lost 75% of units.
besides the typos (numer, thay, onyl) the following sentence needs rewriting
"This happens when the number of enemies destroyed is percentually more relevant than the unit lost."
it should say
"This happens when the your enemy have lost a higher percentage of units than you have"
but it should also say (using the american spelling that is currently in place)
"planes that have left without honor count as lost for the purpose of this calculation"
at the moment it suggests "destroyed" and "lost" are different (really it is just trying to suggest enemy losses vs your losses) - the only difference between destroyed vs driven off the board with no honour is that you don't lose the league point for 'dead' and the opponent doesn't gain the league point for a kill
Retire without honor is treated the same as a kill for league rules. Therefore, your team lost 2 out of 3 planes (67%) and the other team lost 1 out of 2 planes (50%) and they get the victory.