Good evening. We begin tonight with the latest on the baffling and evolving story of Malaysia airlines flight 370, which disappeared en route to beijing with 239 souls on board. In the hours before... See More
Good evening. We begin tonight with the latest on the baffling and evolving story of Malaysia airlines flight 370, which disappeared en route to beijing with 239 souls on board. In the hours before we've come on the air there have been new developments but still no plane. Here's ABC's chief investigative correspondent Brian rossh the mystery of flight 370. Reporter: Tonight the mystery deepened, with authorities saying the plane may have veered far off course after turning off its transponder tracking signal. The flight, en route to beijing, banked hard to the left and then flew for a full hour over hundreds of miles of land, never sounding an alarm, cruising low into the strait of malacca, a busy shipping lane near a tiny rocky island called pulau perak. No boat, no one on land reporting a plane down. It would certainly appear that either the flight crew or there's someone else in the cockpit that is making some decisions that don't really compute. Reporter: Late today a Malaysian general said he had been misquoted about the plane going off course. All part of a fourth day of fruitless searching as Malaysian authorities nevertheless expanded the search grid to take into account the possibility of an off-course vector. 22 aircraft and 40 ships are crisscrossing the area, looking for a needle in a haystack as the bbc's reporter described it. Officials here are using their naked eyes to try to spot anything in the water that seemed to be out of the ordinary. Reporter: But the search has been in disarray from its start. With often incomplete or inaccurate information coming from Malaysian authorities, only adding to the mystery. It's haphazard, it's scattershot. There doesn't seem to be any rhyme or reason. And there doesn't seem to be any centralized control by the Malaysian government. Reporter: And now there is new attention focused on the pilots of the Malaysian air 777 aircraft. Hi, everyone. Reporter: The captain, 53-year-old zahari Ahmad shah, was a pilot's pilot, seen here on his own youtube channel at the controls of a flight simulator. This is a youtube video that I made as a community service. Reporter: A 33-year veteran of the airline with more than 18,000 hours of flying. But his co-pilot, 27-year-old fariq Abdul Hamid, is much less experienced, and today the airline said it was investigating troubling reports he was a kind of airborne playboy, violating safety standards in the cockpit. According to an Australian news report, these two young women were invited by the co-pilot three years ago to ride with him in the cockpit on a flight to Kuala Lumpur. At one stage they were pretty much turned around in their seats talking to us, and they were so engaged in conversation. Reporter: The homes of both pilots have now been searched but so far there'shing about them that suggests foul play. But their backgrounds are coming into sharp focus along with the deepening questions about what happened to Malaysia flight 370. For "Nightline" Brian Ross, ABC news, Washington. Thank you, Brian Ross. We will of course continue to cover this deepening mystery right here on ABC.
This transcript has been automatically generated and may not be 100% accurate.