Gregg Easterbrook wrote the following about simulated shuttle landings: > They've never flounced like a twig on the crazy rapids of "bias"--the bland physics t

Gregg Easterbrook wrote the following about simulated shuttle landings: > They've never flounced like a twig on the crazy rapids of "bias"--the bland physics term for unexplained variations in the earth's gravitational and magnetic fields. I can't make heads or tails out of it -- I can't find any reference to such a phenomenon called "bias" and I don't see how gravitational field variations (I assume he means the ones caused by uneven density) could have any effect at their minuscule amplitude. Is this a result of some misunderstanding or am I missing something?