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In Star Wars: Episode IV - A New Hope, Porkins is killed during the attack on the first Death Star. Just before his X-Wing is destroyed, the following exchange takes place:
PORKINS: "I've got a problem here."
PORKINS: "I can hold it."
BIGGS: "Pull up!"
PORKINS: "No, I'm all - Aargh!"
I don't understand how ejecting would be preferable to being killed outright.
They are in the near-vacuum of space
They are not wearing spacesuits that would support life outside their fighters
They are skimming the surface of a giant battle station that they are trying to blow up.
As such, the only way a pilot could survive ejection, even in the extremely short-term, would be if there was a breathable, relatively warm atmosphere outside the hull of the Death Star. However, even if this were the case, the ejected pilot would only survive until the mission was completed, because he'd still be standing on the Death Star when it exploded. If the mission failed, the rebel attack fleet would presumably be routed or entirely destroyed, and the ejected pilot would be left to wait around until he was spotted by the Imperial forces and, I assume, killed on the spot.
Wookieepedia's stub on ejector seats does little to dispel these apparent problems:
[T]he pilot was left vulnerable to the vacuum of space with little protection other than a flight suit, whereas in an escape pod, ample supplies of food, water, and air were all available. It was important to have rescue and recovery vehicles nearby to retrieve ejected pilots, who could often become lost in the vastness of space.
A rescue seems totally out of the question - before the photon torpedoes enter the exhaust port, all resources have to be directed at getting a torpedo into the port, not rescuing stranded pilots. Once the torpedo enters the exhaust port, there simply isn't time for a rescue. Luke fires the torpedo, sees it go in, and immediately pulls up and tries to put as much distance as possible between himself and the Death Star before it blows up, and even then, he barely makes it out alive.