THE CRASH

On September 22, 2004, at 2:15 pm local time, Oceanic Flight 815 left from Gate 23, and took off from Sydney, Australia, scheduled to arrive in Los Angeles at 10:42. 
 
Approximately six hours into the flight, the crew encountered problems with their radio. Having lost contact with ground control, the pilot decided to alter course and "turn back" towards Fiji. 

Approximately two hours later, having traveled more than 1000 miles off their planned course, the plane hit turbulence, which eventually resulted in the plane's crash. The plane had suffered a mid-air break up and crashed on an uncharted Island, with more than 69 passengers and 2 crew members surviving the crash itself. Later in the series, six of those survivors made it off the Island and became known as the Oceanic Six.
 
Eight hours after take-off would put Oceanic 815 on the Island around 10:15pm Sydney time, later local time since they were flying eastward (Fiji is 2 time zones later, Tahiti is 4). However, it was clearly mid-day when the plane lands, and on the printout from the Pearl found by Locke and Eko, it is clearly shown that the Swan's system failure occurred on September 22, 2004, at 4:16 pm.  This is another indication of the time discrepancy the Island and the outside world.  Similarly, Ajira Flight 316jumped from night to day after experiencing severe turbulence following a bright yellowy white flash.

At first, everyone believed that the airplane crashed due to mid-air turbulence which tore a part the aircraft. Later, on the island, Desmond believed Flight 815's breakup and crash by his failure to enter The Numbers into the Swan computer, causing a large burst of electromagnetic energy. However, the last explanation was that the plane's off-course deviation and arrival to the Island's airspace was  Jacob supernatural ability to bring  the plane because many of the flight's passengers were candidates to replace him as island guardian.

Two months after the crash, wreckage was found in the Sunda Trench in the Indian Ocean near Bali. All of the passengers were presumed dead. In reality, however, the discovered wreckage was staged by Charles Widmore to keep people finding the real plane crash site.  

There are several aspects of the event time line which really do not make much sense. First, if the real reason Flight 815 crashed on the island was that Jacob made it so, then there really was no reason why the pilots were off-course for two hours before the break-up. Jacob could have just instantly taken the plane and diverted it directly to the island. This would have been more feasible especially if his "powers" got all his potential candidates on Flight 815 in the first place. 

In addition, if Jacob had such supernatural powers to divert and break a part of airplane, did he not also have the power to teleport just his candidates from plane as shown when Ajira plane crash landed on the island? The Oceanic Six members were teleported into different times.

It also quite bothersome that if Jacob's sole goal was to get his candidates to the island, why did he need to "kill" 253 other passengers and crew?

The second issue is why Desmond believed he "caused" the crash by not putting in the Numbers. At the time of this reveal, it was an "ah-ha!" moment of clarity to viewers . . . it actually explained a real island event. However, this explanation was taken away as a red herring by the Jacob story arc. It is strange that Hume, who supposedly was not a candidate, somehow got sucked into the island snow globe. The one person who really wanted to get rid of Hume (by manipulation) was Eloise, who actually knew her own "future-past" of killing her time traveling son.  It is also odd that Widmore would have known about the 815 crash on his mystery island when in fact, he could not find it.

The whole idea that Jacob brought other people to the island, including Widmore's mercenaries, to "test" his candidates also seems to be stretch. How did the violent forces of soldiers or even the smoke monster actually factor into the final decision? It did not. Ghost Jacob merely asked for a volunteer in the end. So all the criss-crossing double crossing events on the island had little basis in resolving the reason why Flight 815 crashed and why there were certain survivors.

When one looks backward from Season 6's explanation of the plane crash (Jacob's doing), it really puts no context into the island events. The main characters were like lab rats running a confusing maze for no apparent reason. There is an overlay of cruelty by a bored, unsympathetic supernatural figure, Jacob. Why would he have taunted the pilots with 2 hours of being off-course? Why would he have snapped the plane in two, killing most of the passengers and crew on board? Why would he allow the other inhabitants to kill each other off, then go after his precious candidates?

The LOST story line was like the plane crash: an ugly debris field of a tangled mess of ideas and plots which cannot be put back together.