Narrative:

I am a pilot in az. I was dispatched to ZZZ to pick up a patient who was in critical condition and needed transport to ZZZ1. After I was handed off to ZZZ1 approach I was told I was lower than the altitude I was assigned at 8000 ft. There was a discrepancy between the pilot and copilot's altimeter; so I decided to go off the altitude my GPS was reporting. I was given a phone number; and called when I landed. The patient was transported; and we left an hour later VFR back home. I reported the issue to my lead pilot; and maintenance director. They both took the plane up when I returned and noted the altimeter problem that I had encountered with ZZZ1 approach; and decided that maintenance needed to be done. The lead pilot then flew the plane to ZZZ3 (that day) where it was taken OTS; and maintenance was underway. The following day it was noted that there was in fact an altimeter encoding discrepancy between the pilot and copilot's altimeter; and a broken pipe in the static system. The altimeter was replaced; maintenance was done; and the plane was back in service that evening.

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Original NASA ASRS Text

Title: A KING AIR CAPT ALTIMETER WAS IN ERROR. THE ACFT WAS REMOVED FROM SVC AFTER RETURNING TO HOME BASE.

Narrative: I AM A PLT IN AZ. I WAS DISPATCHED TO ZZZ TO PICK UP A PATIENT WHO WAS IN CRITICAL CONDITION AND NEEDED TRANSPORT TO ZZZ1. AFTER I WAS HANDED OFF TO ZZZ1 APCH I WAS TOLD I WAS LOWER THAN THE ALT I WAS ASSIGNED AT 8000 FT. THERE WAS A DISCREPANCY BTWN THE PLT AND COPLT'S ALTIMETER; SO I DECIDED TO GO OFF THE ALT MY GPS WAS RPTING. I WAS GIVEN A PHONE NUMBER; AND CALLED WHEN I LANDED. THE PATIENT WAS TRANSPORTED; AND WE LEFT AN HR LATER VFR BACK HOME. I RPTED THE ISSUE TO MY LEAD PLT; AND MAINT DIRECTOR. THEY BOTH TOOK THE PLANE UP WHEN I RETURNED AND NOTED THE ALTIMETER PROB THAT I HAD ENCOUNTERED WITH ZZZ1 APCH; AND DECIDED THAT MAINT NEEDED TO BE DONE. THE LEAD PLT THEN FLEW THE PLANE TO ZZZ3 (THAT DAY) WHERE IT WAS TAKEN OTS; AND MAINT WAS UNDERWAY. THE FOLLOWING DAY IT WAS NOTED THAT THERE WAS IN FACT AN ALTIMETER ENCODING DISCREPANCY BTWN THE PLT AND COPLT'S ALTIMETER; AND A BROKEN PIPE IN THE STATIC SYS. THE ALTIMETER WAS REPLACED; MAINT WAS DONE; AND THE PLANE WAS BACK IN SVC THAT EVENING.

Data retrieved from NASA's ASRS site as of May 2009 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.