John Cox| Special for USA TODAY
Question: What is the highest altitude an airplane can reach without getting damaged?
-- submitted by reader Sarah, Victoria, B.C.
Answer: Every airplane has a certified maximum altitude. During test flights this maximum is exceeded slightly to verify the airplane remains safe should it have cause to ascend from that limit. The highest certified altitude of an airliner was Concorde's 60,000 feet. Today some of the corporate jets can fly at 51,000 feet.
Q: What is the highest cruising altitude allowed?
-- RJ, Green Bay
A: Most airliners are limited to 45,000 feet or less.
Q: Is there any altitude where there would be no turbulence?
-- Bill B.
A: Yes, very high altitude, above 50,000 feet, where there is very little air, has little or no turbulence.
Q: If a commercial passenger jet were to climb continually, what would happen at and beyond its ceiling? Engines run out of oxygen? Massive decompression? A bit morbid, but I have always wondered.
-- William; Palatine Ill.
A: Beyond the certified ceiling, the engines would eventually lose the ability to produce enough thrust to continue the climb. There would not be a decompression.
John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.
