Estimates and predictions that turn out to be wrong are still wrong.

And when the estimate was wrong by 50% and counting, and the ATC wasn't offering any information other than another dubious estimate, and the ATC was not handling the flights in a FIFO order, the Lufthansa pilots were left with uncomfortably little useful information about their situation.

Just a note the estimate wasn't just wrong by 50% the pilots had already been told 10min twice before, so estimate was more than 300% off by that time.

When flying and being responsible for an aircraft full of people - estimates take a very different meaning.

That’s why flight plans have diversion fields, with requirements to have enough field to get to the diversion airport, and even to hold _there_.

That also means that when ATC tells someone they will inform them in 10 minutes,they are obliged to tell them in 10 minutes, even if it's "sorry, we don't have a slot, we can get you info in next ten minutes or help you to diversion airport".

Not have to be reminded that there's a plane in holding waiting for information.

Unless they want a repeat of telling a plane to hold till it crashed into sea.