Investigators found no proof of a bomb aboard a Thai Airways flight on Tuesday after a written danger was exposed in a lavatory shortly before its arrival in Los Angeles, officials said.

After landing safely, the Airbus A340-500 taxied to a remote area of the Los Angeles International Airport where official interviewed passengers and crew members, screened luggage and searched the plane.

"No proof has been found to propose a credible threat to the aircraft," FBI spokeswoman Laura Eimiller said.

The FBI is now investigating to decide who was responsible for creation the threat among the 171 passengers and 18 crew members on the Thai Airways International Flight 794 from Bangkok to Los Angeles, she said.

Eimiller could not verify reports that the threat was scrawled on a lavatory mirror.

Los Angeles airport official were notified of the threat around 90 minutes before the flight's scheduled arrival on Tuesday night.

It was not immediately recognized if passengers were conscious of the bomb threat during the flight.

Thai Airways said in a statement in Bangkok that airline officials were waiting for the plane to be released for its go back to Bangkok.

2 American pilots of the UPS cargo plane, who died in a crash, had to survive in the smoke-filled cockpit as they fought to preserve altitude and requested to land at the airport at this time, UAE's civil aviation right said.

Based on a preliminary report, General Civil Aviation Authority supposed air traffic controller here received information from officials in Bahrain at 7:15pm (local time), minutes before the crash that the plane was returning to Dubai after coverage smoke in the cockpit.

United Parcel Service B744 plane left the Dubai International Airport at 6:53pm for Cologne in Germany and crashed into the desert outside the city.

As per report, ATC issued clearance when the plane was approximately 40km from touchdown; however, the ill-fated aircraft was high on the approach 8500 feet at 24km from touchdown.

The plane passed above the airfield "very high", the GCAA said in a statement, adding that it made a right turn before tracking south west and losing altitude rapidly.

At around 7:42pm, radar contact was lost as the B744 crashed in an unpopulated area between the Emirates Road and Al Ain Highway, 50 minutes after being airborne.

The report confirmed that the investigation team had recovered the "black box" the digital flight data recorder about six hours after the accident and is gathering forensic evidence from the scene.

A team from the National Transportation Safety Board will arrive in the UAE to assist the GCAA in the crash investigation.

The crash on Friday killed Captain Doug Lampe, 48, and First Officer Matthew Bell, 38, the Atlanta-based package delivery company said.

Police evacuated 2 terminals at Miami International Airport to investigate suspicious packages and more than a few flights were abstracted to additional parts of the airport, local media reported Friday.

A bomb squad and officials were on the scene investigate a suspicious item found inside luggage in the customs area, according to media reports.

WSVN television said terminals E and F were evacuated around 9:00 pm Thursday and could remain closed off into early Friday.

Passengers and employees were told to leave the affected area.

The Miami Herald said airport traffic slowed to a crawl.

Travelers who could not be picked up by car at the airport left the property on foot instead.