The albatross first appeared to the sailors when their ship was stuck in the ice. The narrator of the poem, the eponymous ancient mariner, says that when the albatross first appeared, it came through the fog "as if it had been a Christian soul," and the sailors, he says, "hailed it in God's name." The implication here is that the sailors all celebrated the appearance of the albatross because they deemed it an omen of good fortune. Indeed, soon after the albatross appeared, the "ice did split with a thunder-fit." Thereafter, "every day, for food or play," the albatross "came to the mariner's hollo!" The suggestion here is that the sailors were fond of and grateful to the albatross and gave it food.
After nine days of fog and mist, the Ancient Mariner shot the albatross. Though they were initially angry at him for this, when the fog and mist were replaced by a blue sky and a warm sun, the sailors agreed that the ancient mariner was right to kill the albatross. They all said, "'Twas right ... such birds to slay, / That bring the fog and mist."
This sudden and fickle change of attitude, from gratitude and fondness to selfish ingratitude and disrespect, may be part of what led to the sailors' undoing. In agreeing with the mariner, it is possible that they became complicit for a time in the mariner's disrespectful killing of the albatross, though they again resented the mariner after several days without wind or water. The sun that they were all initially glad to see began a drought that eventually killed them all (except for the ancient mariner himself). The moral of this story is therefore that humans should always respect the natural world, not just when it suits them to do so.