Planes, ships and submarines are now scouring the waters for a signal and debris from the crash.
As in the search for the missing Malaysian Airlines Flight MH370, which continues more than two years on, finding underwater wreckage is extremely difficult.
While ships searching the area where EgyptAir is believed to have crashed have found some wreckage and human remains in the past few days, the black boxes, which could offer insight on the cause of the crash, were missing.
Batteries that power signals from the airliner s black boxes will likely be exhausted in less than 30 days.
Authorities are anxious to determine what caused the crash.
Officials have oscillated between suggesting the possibility of a terror attack, and cautioning against jumping to any conclusions based on the limited data and evidence collected.