The search for the missing submersible on an expedition to view the wreckage of the Titanic neared the critical 96-hour mark when breathable air is expected to run out, reaching a vital moment in the intense effort to save the five people aboard.
The Titan submersible was estimated to have a four-day supply of breathable air when it launched Sunday morning in the North Atlantic.
That means the deadline to find and rescue the sub is roughly between 6 a.m. EDT and 8 a.m. EDT on Thursday.
Experts say the oxygen supply number is an imprecise estimate.