The debris of the ill-fated Malaysia Airlines flight MH370 that was recovered off the coast of Tanzania led investigators to believe that the missing plane went for a "death dive" and not into a foiled attempt of crash landing.

The fragment, which was part of the inboard section of the right and outboard flap of the plane, was retracted prompting investigators to believe that the ill-fated flight was already unmanned when it made an impact.

Officials from the  Australian Transport Safety Bureau assumed that the pilot were already incapacitated, possibly through lack of oxygen, and the aircraft was on a death dive after running out of fuel.

If the pilots were in controls, the plane could have glided onto the sea while extending the flaps using hydraulic switch.

The ATSB made the confirmation after the Italian part manufacturer asserted that the recovered parts off Pemba Island belong to the missing plane.

The flap bears date stamp, Boeing part numbers and an "OL" numbers that were all unique to the manufacturer.

"The flap section was being examined for any evidence of interaction with mechanisms, supports and surrounding components that may indicate the state of flap operation at the time of separation from the wing," it said.

In an interview of Australian Associated Press, ATSB head Peter Foley said MH370 had not deployed its flaps when it hit the water but retracted inside the wing. A pilot attempting a soft landing would have extended the wing flaps.

"The rate of descent combined with the position of the flap - if it's found that it is not deployed - will almost certainly rule out either a controlled ditch or glide," he said.

HNGN News and Global Headlines earlier reported that the search teams have scaled around 110,000 sq.km. in search for the missing plane with over 20 nations embarking the operations.

As this posting, 22 pieces of debris were recovered along coasts off South Africa, Mozambique, Mauritius, Madagascar and Tanzania.

With the development, Malaysia Transport Minister Datuk Seri Liow Tiong said the search will continue to cover another 120,000 sq km.

"We will continue our search for the missing plane. We have to cover another 120,000 sq km. I promised to the world to complete the 120,000 sq km search area by end of December this year," he told reporters during his official visit to Bintulu Port Authority yesterday.

"This confirmation means a lot to us as we can further examine the debris and uncover new insight into the circumstances surrounding flight MH370," he added.

The plane was carrying 239 people when it went off radar in March 2014. It was on its way to Beijing, China from Kuala Lumpur.