High-Altitude Flights and Risk of Cardiac Disease-Reply

Abstract

In Reply.— Dr Wick states my answer contains an important misstatement: apparently the comment that flight the pilot may increase the cabin altitude to almost 9000 ft due to weather conditions or other aircraft in the vicinity of the flight plan. Despite Dr Wick's reassurances that Federal Aviation Administration regulations prohibit aircraft from operating at a cabin altitude greater than 8000 ft above sea level, at least two studies 1,2 have observed otherwise. Aldrete and Aldrete 1 measured ambient oxygen concentrations and cabin altitudes during 22 commercial flights (707 and DC-9 aircraft). Peak cabin altitudes on these flights measured between 6050 and 8450 ft. Oxygen concentrations varied from 20.9% (sea level) to 15.4% (37 000-ft cruising altitude). Cottrell 2 measured cabin altitude on 204 commercial flights on 16 types of aircraft, operated by 28 airlines. Cabin altitudes measured as high as 8915 ft. Though the median cabin altitude in