Definitely not-for-the-squeamish Delta Air Line's (DAL) stock has plunged in bear-hug fashion during the winter to $9.80 from $14.70, and is now dangerously close to the sell/stop loss at $8.

Delta Air Lines, first discussed here on July 19, 2010, at a price of $10.73, would likely have been a leader of a rejuvenated airline sector until Middle East unrest, including the ongoing civil war in Libya, sent oil prices above $105 per barrel. That crude surge has pushed jet fuel prices -- typically the second biggest or biggest expense for an airline -- substantially higher.

This post is one in a series in which more than 60 newsletter advisors share their Top Stock Picks for 2011. This special report is courtesy of TheStockAdvisors.com.

"Brazil is my favorite emerging country, and we're going to Brazil for our top pick for 2011: GOL Linhas Aereas Intelligentes (GOL)," says Ian Wyatt.

The editor of Top Stock Insights explains, "The rise of Brazil's middle class is good for airlines. And its fast growing emerging economy creates an ideal environment for discount airlines like GOL to set up shop and grow like crazy.

"Is SkyWest (SKYW) undervalued? Indeed, we believe the shares are undervalued at only 0.55 times current book value," says J. Royden Ward.

The editor of Cabot Benjamin Graham Value Letter explains, "The company's P/E of 8.4 and dividend yield of 1.1% is attractive. SkyWest alo has over $13 per share in cash ready to expand its operations. In our view, SkyWest is a classic Benjamin Graham stock.

"Boeing (BA) is on the short list of great American companies; Boeing's heritage as the premier U.S.-based airplane manufacturer is impressive," says Brandon Clay.

The editor of Invest with an Edge explains, "While the company isn't a monopoly on this front, it really only has one legitimate competitor: Airbus. With the global economy improving, at least for now, the airline business is looking up. That's good news for Boeing.

The market should have focused on the downward revision of Q3 GDP to 2.2%. When the benefits of "cash for clunkers" is taken out, the economy barely grew at all.

Stocks ended up being driven by good housing sales figures which were up 7.4% for November and equities were up for a third consecutive day. The market's movement between now and the end of the year will probably be driven by retail sales numbers, but there were few of those today.

The unofficial closing numbers:

Dow 10,464.93 +50.79 (0.49%)
S&P 500 1,118.02 +3.97 (0.36%)
Nasdaq 2,252.67 +15.01 (0.67%)

American Airlines had yet another difficult quarter, not unexpected in what has become an incredibly deep travel slump. The carrier's parent company, AMR Corp. (NYSE: AMR), reported a third quarter loss of $359 million, largely because there aren't as many business travelers taking to the skies. Corporate travel budgets in all industries are having an effect on all airlines, including AMR.

Revenue plunged 20.2% year-over-year for the third quarter for the nation's second airline. The loss comes after a $31 million gain last year. This quarter's losses would have been slightly better if write-downs for sold or grounded aircraft were excluded -- the loss would have been $265 million (93 cents a share) on revenue of $5.09 billion. With the write-downs, revenue clocked in at $5.13 billion. Cheaper fuel made the quarter a little easier for AMR to bear, as well, with this expense down 47% year-over-year.

Republic Airways Holding Inc. (NASDAQ: RJET) is going shopping. Only a day after making an offer for ailing Frontier Airlines (OTC: FRNTQ), it has made a bid to nab Midwest Airlines from private equity firm TPG Capital. The offer consists of $6 million in cash and a note for another $25 million. If the private equity house takes the deal, Republic will get 100% of Midwest's equity and TPG's secured note of $31 million.

The $25 million in debt is convertible to RJET stock at $10 a share, which gives TPG a bit more upside from the transaction. The seller would also have the right to nominate a member of the buyer's board of directors.

Of course, Republic's CEO, Bryan Bedford, is upbeat about the prospect of buying Midwest Airways, saying it will "enhance the strategic positioning" of his company. Like the proposed acquisition of Frontier, Midwest would continue to operate under its own name, though the target's Boeing 717s would be replaced with Embraer 190s.

After the airline went through bankruptcy twice, turnaround expert George Putnam now sees improving long-term prospects for US Airways (NYSE: LCC).

In his The Turnaround Letter, the advisor suggests, "When travel does begin to pick up again, US Air with its lean cost structure should profit handsomely." Here's his review.

"US Airways began in 1939 as All-American Airways delivering mail to Western Pennsylvania and the Ohio Valley; from there it grew through acquisitions to be a major national airline.

A consequence of a weakening airline sector is the pain it will cause plane-maker Boeing (NYSE: BA). With capacity tightening, the need for aircrafts is diminishing.

Imagine planes just sitting idle in the desert. That vision is becoming a reality.

Fortunately for investors, that vision will take time to play out. In the meantime, Boeing gets a free pass as they work through years of order backlog that built up during the last business cycle.

If you take a look at Boeing during the last few months, it is clear that investors have yet to catch on to a world of lower revenues going forward.

The airline industry is a mess and shares of the major airlines are to be avoided at all costs. With an economy that is ailing and fuel hedges gone awry, the sector is once again facing the prospect of steep losses.

Tuesday, we learned how bad it can get for the group. Delta Air Lines (NYSE: DAL) reported a quarterly loss of $1.4 billion, or a whopping $2.11 per share. The company blamed merger costs and bad fuel hedges for the big loss.

As an investor, I really despise the airline sector at the moment. These companies are notorious for being poorly run cash-losing machines.

Now, in the midst of a deep recession and too many airplanes flying too few customers, airline stocks can be expected to be poor performers in the short run and maybe longer.

I made the sector part of my Top 10 Stocks to Avoid in 2009. The main thesis, aside from the obvious recessionary issues, was that oil prices would resume their climb at some point in 2009.

Specifically, I suggested investors avoid Delta Airlines (NYSE: DAL) and United Airlines (NASDAQ: UAUA).

Higher oil prices directly impact the bottom line of the air carriers. The higher oil goes, the more difficult it is for the airlines to make a profit. This summer, with oil prices hitting $150 per barrel, the future of the group was in peril.

That said, the reality of higher prices caused the group to make some necessary changes that included mergers, reduced capacity and important surcharges. The operating environment had the potential to bring much needed discipline to the carriers.

Unfortunately, higher fuel prices did not last long enough to bring enduring change to the group. As prices fell, airline stocks rallied. It was looking good until the economy tanked.

With the recession, oil prices suddenly mattered less. Instead, the focus was on the consumer and business traveler cutting expenses during a contraction.

The airline sector loses if the economy rallies, as such a state brings higher oil prices and lower profit. If the economy stalls, the sector loses customers and revenues fall to unsustainable levels.

The point is that it is no-win situation for the group.

This post is part of a special annual report -- Top Stock Picks '09 -- in which TheStockAdvisors.com asked 75 leading newsletter advisors to select their favorite investment for the new year.

"Airline stocks are looking good now; the airlines should benefit greatly from the big drop in crude oil, as lower crude means lower fuel costs for their operations," notes breakout specialist Leo Fasciocco.

In his Ticker Tape Digest, he looks at Allegiant Travel Co. (NASDAQ: ALGT), a "niche travel airline providing nonstop flights from 53 small cities to large vacation destinations such as Las Vegas and Orlando."

The advisor explains, "The Las Vegas-based company has annual revenues of $483 million. The company also has fixed-fee deals with Harrah's Entertainment to fly certain prespecified routes. The firm's fleet is composed solely of McDonnell Douglas MD-80 aircraft.

"ALGT recently broke clear of a seven-week flat base. Its price pattern of the past few weeks has been a zig-zag with a bias to the upside. The current base is a bit choppy. However, the technicals are extremely bullish. ALGT's push to a new high is very bullish and could bring in more buying.

Even with some modest recovery in airline stocks, it may be too early to celebrate. The worst may not be over for the industry.

The International Air Transport Association says that global losses for airlines could top $6.1 billion this year. The Wall Street Journal quotes ATA Chief Executive and Managing Director Giovanni Bisignani as saying, "We are bracing for more situations of airlines collapsing" amid higher fuel prices and lower revenue.

The slowdown is apparently moving to Asia, a major destination for many large US and EU airlines.

United (NASDAQ: UAUA) is a good example of a US airline that many thought would be on the rebound. New fear of rising oil prices has spoiled that a bit. After falling from a 52-week high of $51.60, shares crashed to $2.80. They have recently made a minor recovery to $12.40. But, in the last two days, UAUA shares have been off sharply.

Oil is still just below $120. Even at that level, down from $143, airlines face huge increases in fuel prices over last year. A modest disruption in oil supply could send prices back up again.

The market sees US airline stocks as having potential for big returns. But, with the price of oil making a potential bottom, the carriers are still in too much trouble to have a real recovery. Buying shares in the companies still offers more risk than reward. The industry may still have operators that have valuations heading toward zero.

Douglas A. McIntyre is an editor at 247wallst.com.

"If there's one sector that stands to benefit handsomely from a further slide in oil or, at least, a moderation in crude's rally: the airlines," explains energy sector expert Elliott Gue.

In The Energy Strategist, he says, "Airlines may make a terrible long-term investment but can be an outstanding short-term trade." Here he looks at Delta Air Lines (NYSE: DAL) and, for the even more speculatively-inclined, US Airways (NYSE: LCC).

"Some investors will rightfully cringe from any mention of this sector; after all, the airlines have consistently lost money throughout their post-deregulation history.

"Most of the majors have declared bankruptcy on multiple occasions since that time. However, we've traded the airlines on a few occasions; we took some triple-digit percentage gains in the airlines back in 2005.

"The airlines' leverage to oil prices is well known. Expectations are so low, in fact, that several major air carriers actually managed to beat consensus expectations in the second quarter.

"And although sentiment is already at rock-bottom, there's a real basis for cautious optimism. First, if I'm right about oil, fuel costs won't rise appreciably in the third quarter. This huge headwind is dissipating.

"The Dreamliner is set to become the most significant new product to hit the airline industry in decades," says Horacio Marquez.

The contributing editor and emerging markets specialist with The Money Map Report states, "Of course, the company that's making the dream machine is Boeing (NYSE: BA), which is consider as compelling an investment as I have ever seen."

"In the world of manufacturing, there's nothing more powerful than a technological leap and right now there's something similar going on in the commercial airplane market.

"Airlines are facing some stiff demands. First, passenger traffic and cargo loads are projected to soar, as are the number of long range flights. Yet soaring oil costs are pressuring carriers to cut back on fuel. Second, carriers are also being pressured to slash carbon emissions and to achieve quieter takeoffs and landings, especially as metropolitan areas become even more congested.

"For jet manufacturers, designing a commercial jet that can do these two critical things is no less a technological miracle than the cell phone was 15 years ago. And Boeing is on the verge of making it happen.