Narrative:

On oct/wed/03, at approximately XA00 hours local, I was conducting a maintenance check flight on an aeronautical commander. I filed an IFR flight plan from eye to bvt to eye. During the climb we were handed off to ZAU and cleared direct to the bvt VOR. We were checking for pressure leaks in the aircraft as well as other items. We had advised ATC that we were conducting a maintenance test flight. While we were at altitude (FL310) we were given a vector to follow and we remained on the heading for a long period of time. Due to the pressure leaks in the aircraft, the crew became slightly hypoxic. While we were completing our maintenance checks, I looked at the GPS and noticed that we were off course. I made a large turn to try and correct the problem. ATC then asked me if I had made a turn and I responded that I had. Corrective actions: improved communications between ATC and flight crews while conducting maintenance flight checks to ensure that the flight is proceeding smoothly and without problems. Continue to educate pilots and flight crews on the dangers of hypoxia and how it can cause disorientation.

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Original NASA ASRS Text

Title: AC690 PLT HAD A TRACK DEV IN ZAU CLASS A, AFTER THE PLT BECAME HYPOXIC, WHEN THE ACFT WAS UNABLE TO MAINTAIN PRESSURIZATION BECAUSE OF PRESSURE LEAKS.

Narrative: ON OCT/WED/03, AT APPROX XA00 HRS LCL, I WAS CONDUCTING A MAINT CHK FLT ON AN AERO COMMANDER. I FILED AN IFR FLT PLAN FROM EYE TO BVT TO EYE. DURING THE CLB WE WERE HANDED OFF TO ZAU AND CLRED DIRECT TO THE BVT VOR. WE WERE CHKING FOR PRESSURE LEAKS IN THE ACFT AS WELL AS OTHER ITEMS. WE HAD ADVISED ATC THAT WE WERE CONDUCTING A MAINT TEST FLT. WHILE WE WERE AT ALT (FL310) WE WERE GIVEN A VECTOR TO FOLLOW AND WE REMAINED ON THE HEADING FOR A LONG PERIOD OF TIME. DUE TO THE PRESSURE LEAKS IN THE ACFT, THE CREW BECAME SLIGHTLY HYPOXIC. WHILE WE WERE COMPLETING OUR MAINT CHKS, I LOOKED AT THE GPS AND NOTICED THAT WE WERE OFF COURSE. I MADE A LARGE TURN TO TRY AND CORRECT THE PROB. ATC THEN ASKED ME IF I HAD MADE A TURN AND I RESPONDED THAT I HAD. CORRECTIVE ACTIONS: IMPROVED COMS BTWN ATC AND FLT CREWS WHILE CONDUCTING MAINT FLT CHKS TO ENSURE THAT THE FLT IS PROCEEDING SMOOTHLY AND WITHOUT PROBS. CONTINUE TO EDUCATE PLTS AND FLT CREWS ON THE DANGERS OF HYPOXIA AND HOW IT CAN CAUSE DISORIENTATION.

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.