Gulfstream iv PF interpreted foreign altimeter setting as equal to inches of mercury instead of mill...

Attributes
ACN	548946
Time
Date	200205
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : einn.airport
State Reference	FO
Altitude	msl bound lower : 3000 msl bound upper : 4000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Gulfstream IV
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	approach : visual arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12000 flight time type : 5000
ASRS Report	548946
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : overshoot inflight encounter : weather non adherence other
Independent Detector	aircraft equipment other aircraft equipment : altimeter other controllera
Resolutory Action	controller : issued alert controller : issued new clearance flight crew : became reoriented flight crew : returned to original clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Weather Flight Crew Human Performance Environmental Factor ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Chief pilot, PF with limited international experience, limited experience in type. PNF captain with extensive international (expatriate work) 5000 hours in type. During descent for approach to shannon, ireland under radar control, we were cleared to 4000 ft with local altitude setting 975 hectopascals, transition level 5000 ft. PF seemed confused about hectopascals. I explained that it was the same as millibars. I called radar to verify that hectopascals and millibars were the same for his information. I set 975 millibars on the right side altimeter as we approached 5000 ft. I reminded him of the correct altimeter setting. He informed me I did not know what I was talking about and the pressure setting could not be that low. He said that he heard ATC say that hectopascals and inches were the same. I explained that I had been to ireland many times and that he was wrong, and it was common to have low pressure area over ireland. He became aggressive, offering to bet me $100, etc, that I was wrong. At that time we were in visual conditions with no other traffic in the immediate area. I decided it best not argue at this time as we were still above the MSA. He had set 29.75 inches on his side. 4000 ft set in the altitude alert. The autoplt leveled the aircraft indicating 4000 ft based on his altimeter and the altitude alert system. My altimeter (copilot side) indicated 3000 ft. ATC asked to verify altitude, I quickly said 3000 ft. ATC says you were cleared to 4000 ft. At that time the captain answered ATC asking to verify altimeter setting and that hectopascals and inches were the same. ATC quickly confirmed setting was not inches, but hectopascals or millibars. Finally he set it correctly and began a climb back to 4000 ft, by now ATC said stay at 3000 ft. A short time later, we were cleared for the visual approach and switched to the tower control frequency. No mention was made about the error. I saw no point to bring it up as I had 10 days and many countries still ahead, including a flight to russia where flight levels are in millimeters. I suspect the irish ATC will not file a report. They were probably thinking just more inept americans, and they seemed anxious to help us on our way to france after refueling. Fortunately, the WX was good and ATC was alert. If necessary I was prepared to take control of the aircraft.

Original NASA ASRS Text

Title: GULFSTREAM IV PF INTERPED FOREIGN ALTIMETER SETTING AS EQUAL TO INCHES OF MERCURY INSTEAD OF MILLIBARS, CAUSING INTERMEDIATE APCH ALT TO BE OVERSHOT.

Narrative: CHIEF PLT, PF WITH LIMITED INTL EXPERIENCE, LIMITED EXPERIENCE IN TYPE. PNF CAPT WITH EXTENSIVE INTL (EXPATRIATE WORK) 5000 HRS IN TYPE. DURING DSCNT FOR APCH TO SHANNON, IRELAND UNDER RADAR CTL, WE WERE CLRED TO 4000 FT WITH LCL ALT SETTING 975 HECTOPASCALS, TRANSITION LEVEL 5000 FT. PF SEEMED CONFUSED ABOUT HECTOPASCALS. I EXPLAINED THAT IT WAS THE SAME AS MILLIBARS. I CALLED RADAR TO VERIFY THAT HECTOPASCALS AND MILLIBARS WERE THE SAME FOR HIS INFO. I SET 975 MILLIBARS ON THE R SIDE ALTIMETER AS WE APCHED 5000 FT. I REMINDED HIM OF THE CORRECT ALTIMETER SETTING. HE INFORMED ME I DID NOT KNOW WHAT I WAS TALKING ABOUT AND THE PRESSURE SETTING COULD NOT BE THAT LOW. HE SAID THAT HE HEARD ATC SAY THAT HECTOPASCALS AND INCHES WERE THE SAME. I EXPLAINED THAT I HAD BEEN TO IRELAND MANY TIMES AND THAT HE WAS WRONG, AND IT WAS COMMON TO HAVE LOW PRESSURE AREA OVER IRELAND. HE BECAME AGGRESSIVE, OFFERING TO BET ME $100, ETC, THAT I WAS WRONG. AT THAT TIME WE WERE IN VISUAL CONDITIONS WITH NO OTHER TFC IN THE IMMEDIATE AREA. I DECIDED IT BEST NOT ARGUE AT THIS TIME AS WE WERE STILL ABOVE THE MSA. HE HAD SET 29.75 INCHES ON HIS SIDE. 4000 FT SET IN THE ALT ALERT. THE AUTOPLT LEVELED THE ACFT INDICATING 4000 FT BASED ON HIS ALTIMETER AND THE ALT ALERT SYS. MY ALTIMETER (COPLT SIDE) INDICATED 3000 FT. ATC ASKED TO VERIFY ALT, I QUICKLY SAID 3000 FT. ATC SAYS YOU WERE CLRED TO 4000 FT. AT THAT TIME THE CAPT ANSWERED ATC ASKING TO VERIFY ALTIMETER SETTING AND THAT HECTOPASCALS AND INCHES WERE THE SAME. ATC QUICKLY CONFIRMED SETTING WAS NOT INCHES, BUT HECTOPASCALS OR MILLIBARS. FINALLY HE SET IT CORRECTLY AND BEGAN A CLB BACK TO 4000 FT, BY NOW ATC SAID STAY AT 3000 FT. A SHORT TIME LATER, WE WERE CLRED FOR THE VISUAL APCH AND SWITCHED TO THE TWR CTL FREQ. NO MENTION WAS MADE ABOUT THE ERROR. I SAW NO POINT TO BRING IT UP AS I HAD 10 DAYS AND MANY COUNTRIES STILL AHEAD, INCLUDING A FLT TO RUSSIA WHERE FLT LEVELS ARE IN MILLIMETERS. I SUSPECT THE IRISH ATC WILL NOT FILE A RPT. THEY WERE PROBABLY THINKING JUST MORE INEPT AMERICANS, AND THEY SEEMED ANXIOUS TO HELP US ON OUR WAY TO FRANCE AFTER REFUELING. FORTUNATELY, THE WX WAS GOOD AND ATC WAS ALERT. IF NECESSARY I WAS PREPARED TO TAKE CTL OF THE ACFT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Gulfstream iv PF interpreted foreign altimeter setting as equal to inches of mercury instead of millibars, causing intermediate approach altitude to be overshot.