Are we sure that the "market cap:book value ratio" is not an artifact of a) the stock price being marked down by the market, while b) their (e.g.) planes have n

Are we sure that the "market cap:book value ratio" is not an artifact of a) the stock price being marked down by the market, while b) their (e.g.) planes have not been explicitly revalued in light of the lower demand? That's probably why the board doesn't shrug and vote to liquidate assets and pay shareholders more than their shares are worth.