Editor's note: Robert Goyer is the editor-in-chief of Flying magazine and a commercial jet-rated pilot. The opinions expressed in this commentary are solely those of the author.
(CNN) -- Dealing yet another blow to an investigation desperate for clues, investigators have determined that debris spotted by aircraft in the search for Malaysia Airlines Flight 370 was not part of the lost airliner. Without a break in the case that would lead investigators quickly in the direction of the Boeing 777-200 that disappeared March 8, it is likely that we will never find the wreckage, even if debris does turn up in the coming weeks, months or years.
To get a sense of the odds at play here, let's put the current state of the investigation into perspective.
Searchers are focusing on an area of the southern Indian Ocean about the size of New Mexico, and this search locale is only a best guess -- one based on clever satellite science but also on some big assumptions about what altitude the 777 was flying at, how fast it was going and what direction it was headed, as winds are a critical part of the guesswork.
How good a guess is it? We simply won't know until we find debris. Lacking such a discovery, we will never know.
The underlying question is: Are searchers even looking in the right part of an unimaginably giant expanse of ocean? I do not know, and the truth is, based on what investigators have told us, neither do they.
But even if the search is in the right neighborhood, remember that they are scouring this enormous area in aircraft and in boats looking for debris that could be no larger than about 60 feet long and 20 feet wide; more likely, such debris will be even smaller. The searchers are seeking these physical clues mostly with the naked eye and within an area littered with many millions of pieces of floating debris, much of it not much different looking than the pieces of wreckage that we would expect in the crash of a large transport airplane in the open ocean.
Because it's been more than three weeks since that presumed crash, it's almost certain that that debris will be widely scattered by now. This is perhaps the most sobering detail: Finding debris definitively associated with Flight 370 will in no way guarantee finding the main wreckage, though the sooner search teams spot such debris the more likely they will be able to narrow the scope of the search for the main wreckage.
But even if we were to narrow that scope greatly, it almost certainly will be too late for searchers to get close enough with their submersibles to hear the faint pinging of the flight data and cockpit voice recorders, which could be many miles below the surface of the ocean and in an area of treacherous and deep underwater canyons.
There are, of course, lessons to be learned from the search for and eventual discovery of Air France Flight 447, an Airbus A330 that crashed in the Atlantic in 2009. Despite debris and victims being located on the surface a day after the crash and near where the jet went down, the hunt for the wreckage was never a sure thing. In fact, searchers never heard the "black boxes" ping, and it took nearly two years for them to locate the airplane's wreckage.
In short, if searchers in the disappearance of Flight 370 were to find a clue, they still would be facing steep odds of ever finding its wreckage, which at this point might be the only way that this mystery will be solved.
If investigators are wrong in their assumptions, if Flight 370 is somewhere far from where ships and planes are looking for it now, the chances of finding it are close to zero.
We can only hope that investigators know more than they are so far telling us. A couple of days ago, they did send out an advanced Australian navy search vessel, the Ocean Shield, with a towable submersible, called Bluefin 21, outfitted to listen for pings from the black boxes.
My hope is that they dispatched these specialized resources not because they were looking for a lucky break but because they have somehow narrowed the search area substantially and have not said so to avoid raising expectations among the families and friends of victims waiting for answers to a mystery that might remain unsolved forever.