Dc8-70 flight crew overshoots their cleared altitude because the captain's altitude was incorrectly set.
Synopsis
Dc8-70 flight crew overshoots their cleared altitude because the captain's altitude was incorrectly set.
Narrative
Rewritten in plain English from NASA’s original all-caps telegraphic report — facts, figures, and terminology preserved.
Enroute from Toledo Express via direct GSH VOR; captain flying. We were cleared to flight level 220 and told that we could expect higher when clear of traffic passing off our right side. We reported the traffic in sight and watched it pass behind us.
At flight level 180 both pilots reset altimeters and called out 'set 2ument 29.92.' At flight level 217 on the captain's altimeter, the co-pilot remarked that the cleared altitude was flight level 220 which the captain acknowledged. The co-pilot then stated that there was an altitude discrepancy between the altimeters and that his altimeter was indicating flight level 227, 1000 feet higher than the captain's altimeter. The flight engineer noticed that the captain's altimeter was set to 28.92 instead of 29.92.
Just as the captain corrected his altimeter and began a descent, ZAU called and asked what our altitude was and told 227. Controller then cleared us to flight level 230. The captain should have set his altimeter correctly and checked the co-pilot's altimeter for agreement. The co-pilot did not notice the altitude deviation on his altimeter until we were 700 feet high and the flight engineer should have checked that the 2 altimeters were set and that they agreed.
The main factor contributing to this incident was fatigue. This was a night freight flight and although the crew had been on duty for only 2 hours they were into their 18th hour of the day with another 5 hours to go until the next rest period.
Show the original NASA report (verbatim, telegraphic)
ENRTE FROM TOLEDO EXPRESS VIA DIRECT GSH VOR; CAPT FLYING. WE WERE CLRED TO FL220 AND TOLD THAT WE COULD EXPECT HIGHER WHEN CLR OF TFC PASSING OFF OUR R SIDE. WE RPTED THE TFC IN SIGHT AND WATCHED IT PASS BEHIND US. AT FL180 BOTH PLTS RESET ALTIMETERS AND CALLED OUT 'SET 29.92.' AT FL217 ON THE CAPT'S ALTIMETER; THE COPLT REMARKED THAT THE CLRED ALT WAS FL220 WHICH THE CAPT ACKNOWLEDGED. THE COPLT THEN STATED THAT THERE WAS AN ALT DISCREPANCY BTWN THE ALTIMETERS AND THAT HIS ALTIMETER WAS INDICATING FL227; 1000 FT HIGHER THAN THE CAPT'S ALTIMETER. THE FE NOTICED THAT THE CAPT'S ALTIMETER WAS SET TO 28.92 INSTEAD OF 29.92. JUST AS THE CAPT CORRECTED HIS ALTIMETER AND BEGAN A DSCNT; ZAU CALLED AND ASKED WHAT OUR ALT WAS AND TOLD FL227. CTR THEN CLRED US TO FL230. THE CAPT SHOULD HAVE SET HIS ALTIMETER CORRECTLY AND CHKED THE COPLT'S ALTIMETER FOR AGREEMENT. THE COPLT DID NOT NOTICE THE ALTDEV ON HIS ALTIMETER UNTIL WE WERE 700 FT HIGH AND THE FE SHOULD HAVE CHKED THAT THE 2 ALTIMETERS WERE SET AND THAT THEY AGREED. THE MAIN FACTOR CONTRIBUTING TO THIS INCIDENT WAS FATIGUE. THIS WAS A NIGHT FREIGHT FLT AND ALTHOUGH THE CREW HAD BEEN ON DUTY FOR ONLY 2 HRS THEY WERE INTO THEIR 18TH HR OF THE DAY WITH ANOTHER 5 HRS TO GO UNTIL THE NEXT REST PERIOD.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.