After almost three days, authorities tell us, there's not a trace of the Boeing 777-200ER flying as MH370 from Kuala Lumpur to Beijing.
One moment it's at Flight Level 350; the next it's off the radar. According to Reuters, Boeing reps say no ACARS messages were received after contact was lost. So all we have are bits of indirect evidence that might, or might not, link to whatever happened: a mumbled radio transmission, the fact that at least two passengers boarded with false passports.
As I described in this post about missing airliners, it is extremely rare (but not completely unprecedented) for a commercial airliner to disappear without a trace then go undetected for years. When I looked through the records, I only found one such case in modern times: a Pakistan International Airlines Fokker-27 turboprop with the call letters AP-BBF, which flew off into the mountains on August 25, 1989, with 54 souls. No piece of the AP-BBF, nor any human remains, have been found over a quarter century.
Here's a picture (www.historyofpia.com):
The commentators are correct in calling Flight 370 unprecedented in that the 777 has a very good safety record, and had locator electronics that are supposed to aid rescuers in finding whatever remains.
The original flight path was not over deep waters, which are colored dark blue in this map (map, NBC):
Normally the acoustic pingers embedded in Flight Data Recorders and Voice Data Recorders on such aircraft would make them relatively easy to find within a few days, in such shallow waters. This suggests either that a something destroyed the recorders over the ocean -- quite unlikely, given how tough they are -- or else the airplane is quite a distance from the last reported position. Search efforts are now expanding considerably to the west, in case the airplane headed that direction while off the radar screens (map, WashPost:)