Until a couple of days ago, Malaysian Airlines owned or operated seventeen extended range Boeing 777s. Then, on the 8th, the 777-200ER operating flight MH370 from Kuala Lumpur to Beijing was lost in flight with 239 souls on board. Wreckage has not yet been found.
(Tangential connection: Malaysian Airlines operates flights between Amsterdam and Kuala Lumpur using 777-200ERs. Indeed, my wife and I flew KUL-AMS last April—there's a non-zero chance that I've flown on the aircraft that was lost, although we didn't make a note of the tail number at the time.)
I am now about to engage in baseless conspiracy-theorizing, which as you know has an almost zero probability of being an accurate reflection of the actual cause of the tragedy.
It has emerged that at least two passports used by passengers who booked tickets on MH370 were stolen—one Austrian and one Italian—in Thailand. The persons using these passports bought consecutive ticket numbers the day before MH370 departed, paying Thai Bhat to a China Southern rep: their tickets would have been issued by China Southern but the flight was operated by Malaysian as a code-share.
There are quite a lot of stolen and forged passports out there, and the probability of one being held by a passenger on a downed flight is non-zero: but the issue of consecutive-numbered tickets to two people with stolen passports suggests they were colluding or travelling together, for whatever purpose.
Per The Guardian
Both passengers used Thai baht to purchase their travel tickets on 6 March, a day before the flight took off from Kuala Lumpur destined for Beijing.This routing should have raised concern at the time. Malaysian Airlines planes fly direct from KUL-AMS every day: why pay extra to spend ten hours in the transit lounge in Beijing?
The pair, who booked tickets with consecutive numbers, were due to fly to Beijing, then wait for around 10 hours before flying to Amsterdam. Once they arrived in Amsterdam, one of the passengers was due to travel on to Frankfurt and the other to Copenhagen.
However, if their objective was to get on a China Southern airliner bound for Beijing without having to fill out a Chinese visa application and thereby coming to the attention of the Chinese authorities—and if they didn't know about codeshares—this would be one way to do it.
Note: EU citizens transiting Beijing can obtain a 72-hour transit visa without applying in advance. It doesn't let them into the country, but it means they don't have to fill out any paperwork before they arrive, unlike the USA's advance passenger information requirement (which must be filed at least 72 hours before arrival).
It's fairly clear that China Southern were not checking the passport numbers presented at the point of sale against lists of stolen or cancelled passports.
Let us bear in mind that while Uighur separatists seem happier attacking railway stations with knives, Al Qaida spokesmen have denounced China as an "enemy of Islam" in the not-too-distant past.
Airline security in that part of the world is lax compared to the USA/EU. KUL operates gate security with cursory passport checking. I've no idea how easy it would be to get a suitcase onto the plane un-inspected, but I had the distinct impression that baggage checks were rather more cursory than in the west. Maybe somebody thought that tactics that won't work here any more might still come in useful ...
I will be a lot happier if it is determined that this tragedy was the result of operator errors or a catastrophic mechanical failure, and the forged passports turn out to have been related to drug smuggling or human trafficking, or some other mundane crime. Because we can fix problems with aircraft and prevent this from happening again, and in the grand scheme of things petty crime does not signify. But the kind of human malice that would kill 240 random strangers to make a political point is something else, and if this was an act of terrorism then it is on a scale with the bombing of Pan Am Flight 103 over Lockerbie or of Air India 182 over the Atlantic. And I hope whoever planned it died in the act, or is sleeping very uneasily tonight.