about half an hour earlier during their flight from gran canaria to mauritania one of the planes had mysteriously lost cabin pressurization so had to descend to below ten thousand feet ( and unfortunately off the rather basic air traffic control radar screen covering that area ) , and the other one of course had to keep in company ( for safety reasons ) , and as david detached him , the aircraft that they had only recently vacated came in low , very low , and out of its open loading ramp came a parachute , attached to yet more pallets which all came safely to a standstill about twenty meters away .