An Indonesian man has described how Jakarta's notorious traffic inadvertently saved his life yesterday after he arrived too late to catch the doomed Lion Air plane which plunged into the sea minutes after taking off.

Sony Setiawan, an official in Indonesia's finance ministry, had meant to be on board the ill-fated flight JT610, a journey he and his colleagues caught on a weekly basis.

But while his friends battled their way through Jakarta's daily congestion to make the flight, Sony found himself stuck on a toll road for hours.

"I usually take (flight) JT610 -- my friends and I always take this plane," Setiawan told AFP. "I don't know why the traffic at the toll road was so bad. I usually arrive in Jakarta at 3am but this morning I arrived at the airport at 6:20 and I missed the flight."

That gridlock likely saved Setiawan's life as officials warned it was unlikely anyone would have survived such a crash.