Now, a third major red flag has emerged in the sky, where the slowdown in sales and new orders for airplanes is now so acute that US plane giant, Boeing, announced on Monday it would refrain from increasing jetliner prices for the coming year, the first time it has held prices steady since 2009.

"Boeing will continue to quote July 2015 base prices in 2016," company spokesman Doug Alder said in an email to Reuters. A tactic typically invoked during recessionary periods Boeing has held prices steady during sales slow-downs in the past. It did not increase prices in 2001 or 2009, Alder noted.‎ Boeing and Airbus sales fell precipitously those years following the Sept. 11, 2001, attacks and the financial crisis.