Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

DALLAS — A Boeing 767 appears to have hit turbulence a minute before it dropped into a rapid descent and smashed into a Texas bay in February, killing all three people aboard.

The National Transportation Safety Board says "small vertical accelerations" suggest Atlas Air Flight 3591 entered turbulence soon after the pilots had descended to avoid a band of precipitation as they approached a Houston airport.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Seconds after leveling off around 6,200 feet, the cargo plane's engines surged to "maximum thrust" and it briefly pointed its nose 4 degrees up, according to flight data. The jet then rapidly swung to point 49 degrees downward and began its drop toward the muddy bay.

The NTSB does not give a reason for this sharp change in pitch, but says the plane's stick shaker, which warns of an imminent engine stall, did not activate. That means it's unlikely the pilots pointed the nose down to avoid stalling.

The federal agency previously said cockpit audio suggests the pilots lost control while passing over Trinity Bay, about 40 miles east of George Bush Intercontinental Airport.

As the plane dropped, the agency says, it accelerated to 495 mph and gradually pulled up to a 20-degree descent.

The jet, which had been carrying cargo from Miami for Amazon and the US Postal Service, disintegrated upon impact with the shallow bay.

The NTSB says investigators found one of the plane's engines and some landing gear west of the main debris field, which spread over 350 yards of the swampy area.

The tidal waters carried some parts of the plane and much of its cargo south, and some wreckage was recovered up to 20 miles from the crash site.