Even a perfect sensor will accumulate errors in the nav solution over time because there's no such thing as a perfect gravity model. No free-running INS will ever replace GPS long term. This shit is so frustrating to see in the press.
I don't think you'll ever see an INS going months without needing a correction. Imperfect gravitational compensation applies directly to the specific force measurements and those errors are then accumulated twice.
‘It’s the perfect place’: London Underground hosts tests for ‘quantum compass’ that could replace GPS ( www.theguardian.com )
Which are the most fucked up books you've read?