What happened

Shares of American Airlines Group (AAL -0.38%) crashed 9.4% through 11 a.m. ET on Wednesday after the company filed a first-quarter investor relations update with the Securities and Exchange Commission (SEC) that had both good news and bad news for investors.

So what

Good news first: In Q1, American Airlines flew 65 billion "total available seat miles" (if you multiply all the seats on all the airplanes it has by the number of miles on all the flights American flew in the quarter, the result is 65 billion). That number was up 9.2% year over year, and slightly ahead of management's own forecast.  

Even better, American Airlines charged a lot of money for these seats, and its "total revenue per available seat miles" soared 25.5% -- nailing the midpoint of previous guidance. Similarly, the company says its adjusted operating profit margin for the quarter was exactly in the middle of guidance: 3.5%.

But now here's the bad news: After crunching all those numbers, American Airlines concluded that this quarter's earnings will range from $0.01 to $0.05 per share. And that's a lot less than the $0.07 per share in adjusted profit that Wall Street was expecting.  

Now what

So long story short, American Airlines just warned investors that it's going to miss analyst targets when it officially reports Q1 earnings on April 19 -- and investors aren't happy to hear that. Missing earnings in Q1 is going to make it harder for the company to hit forecast earnings of $1.86 per share this year.

But here's the thing that long term investors in this airline stock should be focusing on:

Earning $1.86 in profit this year would mean American Airlines stock is valued at a cheap 7 times current year earnings. But even if American Airlines doesn't earn quite that much -- say it earns only $1.50, 20% less than forecast -- the stock would still look incredibly cheap at a P/E of less than 9, especially given that, according to forecasts from S&P Global Market Intelligence, American Airlines is on course to grow those earnings four times in the next four years.

If you ask me, today's sell-off in American Airlines stock is kind of looking like a good opportunity to buy.