We play by letting the dice fall where they may, and this includes me as the DM. I roll all dice in front of the players so they can see it is all completely above board and fair.
We lost the party fighter to the future King of the Orcs, who had found a magical spear that could unite the disparate orc tribes that the party were also looking for (to keep it out of their hands in fact). The group had left the citadel they were exploring to restock their supplies and train up, even though they knew they were only an hour behind someone else who was sneaking around in the ruins. When they returned to the ruins, there was an orc host emerging from the citadel with much fanfare! One of the orcs was holding a spear aloft that glinted in the light. All told, there was a robed figure, a wolf, four orcs, an orog and two kobolds. After a little debate, the party decided to attack and remove the threat to civilisation. It was in this fight that the fighter fell to the orc with the dread spear, certainly, an honorable death.
The next battle they fought had the most surprising results. It was against merely six orcs who were skulking around the courtyard in the citadel. They had probably heard the party's bard who was breaking crates into pieces and hammering bits of them over the doorway of the room that the party was going to rest in. On spying the orcs, the adventurers attacked! However, one of their henchmen was cut down in a vicious melee, then the party wizard was brought down by two orcs with short bows and a similar fate was waiting for the bard. Luckily the wizard was only knocked unconscious, but the bard was slain.
In both cases of character death, the players just rolled up new characters and the game carried on. So instead of a fighter and a bard, we now have a cleric and a fighter. Attrition rate is proving to be high - but that goes hand in hand with an appropriate danger level for the campaign. Also, in both cases the party did not have to fight, but chose to anyway. That, I think, makes all the difference!
Neither player complained, they got 3d6 out and started rolling up new characters - one of which has an 18 - our first natural 18 on 3d6 in 8 months of playing!