[jahewson]

There are costs to sticking with the imperial system. Non-US buyers want metric products which fit with their existing tooling. The factories of the world want all-metric manufacturing, which reduces costs. Error from unit conversion is a real problem.

Designing new products in metric wouldn't require old products to be replaced with imperial. Each product line has it's own special repair kit, spare parts, already. It's not like the suppliers who actually make parts aren't equipped to do metric if they're selling parts worldwide.

The UK went metric in the 1960s and it managed just fine, so there's no reason why it can't be done. Some pragmatism can be involved, for example road signs in the UK are still in miles, and one can still buy a pint of milk or beer (though the latter are technically labelled and sold in millilitres).

A move to metric wouldn't dictate the internal practices of a company like Lockheed, they could still require their suppliers to build parts in inches (even if that means that formally they purchase 2.6234cm sized screws or similar) and they can continue to do everything in inches. Not that they'd want to.

[rmc]

Ireland also went metric. We switched road speed limits in 2006ish, so all the signs say "km/hr" so you don't forget (it's also helpful to tell when you cross the border unto hr uk). Beer is sold in 568ml (1 pint), but milk is sold in litres.

[stephen_g]

It's quite interesting in Australia that you buy a pint of beer if it's in a glass (or a pot, which is much smaller or schooner, pronounced 'skooner', which is a bit smaller), but bottles are never sold as imperial are generally 375mL.

[jarek]

In England cans of cider are 500 mL. Honestly I don't really think a pint is a unit (except for old people buying milk?), it's a descriptor like "a glass" or "a pitcher" that just happens to have a legally required size. I have an idea roughly how much a pint is but I wouldn't requisition three pints of hydrofluoric acid.