HUNTSVILLE, Ala. (WHNT) -- The National Transportation Safety Board arrived in Huntsville Thursday morning to begin documenting the accident site for Wednesday's fatal plane crash.
NTSB learned that the pilots were performing training exercises at Huntsville International Airport.
Two of the victims were company contract pilots for the owner of the plane, Synfuels Holdings Finance, LLC, out of Birmingham.
Investigators are still unsure of which two pilots were receiving the training and why they were in Huntsville.
According to the flight tower audio tape, the three men set out Wednesday to practice practice two instrument landing approaches. In those approaches, pilots focus on guiding the plane to a precise altitude above the runway.
The tape indicated that the pilots would fly to Birmingham after the two exercises.
NTSB Senior Air Safety Investigator Tim Monville said while they do not yet know why the plane crashed, but they do know what happened.
"By witness accounts the airplane climbed no higher than 50 to 100 feet off the ground and was observed to bank hard or steep to the right," said Monville. "The airplane impacted west of the runway and was destroyed by impact and, of course, crash fire."
All three men were certified pilots, though investigators say they will look at the men's experience.
The tower audio also indicated that no distress calls were made prior to the crash.
NTSB spent Thursday searching for the cockpit voice recorder. They think they have located it, but they have yet to recover it.
Investigators will also comb through maintenance records of the aircraft.
"We have to look at a lot of different systems of the airplane to show what systems could have caused a discrepancy, if any, and so we've got to rule them out," said Monville.
Once they finish their on-site work, NTSB will then move the plane to a secure location for further investigation.
NTSB will be in Huntsville until at least early next week to finish the on-site investigation.
They expect the investigation up to a year to complete, but they plan to have a preliminary report published in ten days.
"With what we have factually, the physical portion of the aircraft, coupled with the cockpit voice recorder is going to be a big help for determining what happened in the sequence," said Monville.