RNZAF Bell 47
Just before the mighty Bell 47 Sioux was retired from 'operational' service in the RNZAF (circa 1986), an attempt was made to reach the promulgated service ceiling (20,000ft). Our AvMed folks stipulated portable oxygen (of course) and two pilots, which cut down the odds slightly. Still, they made it to 19,600ft PA. Bruce/Pete: If you're out there, you may still have the photo.