Narrative:

On final approach for runway 32 ILS at pittsburgh international, the captain descended below the 4000 ft published step-down altitude prior to the step-down point. I advised him he was low and going below glide path. He corrected back to the GS. About that same time, approach control also advised him he was below the published altitude at that distance from the airport. He acknowledged, reintercepted the glide path well prior to the OM, and completed a normal final approach and landing. We were in good VMC conditions at the time, with the airport, ground and aircraft in front of us (about 4 NM) in sight. I believe there were numerous contributing factors for this situation to develop. The first factor is fatigue. This was the last day of a very long 4 day trip characterized by long duty days due to WX delays and deviations (thunderstorms) flying coast to coast each day, sfo-bwi-lax-pit. As a result, the scheduled 24+ hour trip ended up being a 27 hours 22 min trip. This last day of the trip started at XA15 in lax and ended at XH32 in pit. The last leg was scheduled for 57 mins, but was actually 1 hour 43 mins due to traffic/WX delays for takeoff and large en route deviations to avoid thunderstorms and cumulo nimbus. The second factor in this situation was the non standard arrival due to WX and traffic on the arrival/descent to pit. We were filed and cleared for the nesto arrival to pit, but prior to nesto, while we were descending to 10000 ft MSL, approach control vectored us to intercept the runway 32 localizer. This put us on final approach at a higher than desired altitude. The captain elected to slow and configure the aircraft to expedite our descent to the published approach altitudes. After we had slowed to about 170 KTS, approach control directed us to increase to 210 KTS. The captain complied and we again changed the aircraft confign to match the increased airspeed. The captain was concerned about closing on the #1 aircraft on final (we were #2) and also being too high and fast at the OM. This is when he inadvertently descended below the 4000 ft published step-down altitude. I believe his fatigue combined with the non standard, somewhat rushed approach caused him to focus on his airspeed and the other aircraft to the point that his altitude awareness suffered. Fortunately, both myself and the approach controller backed him up and caught the problem before it became more serious. The system worked.

Related reports:

Google
 

Original NASA ASRS Text

Title: ALT OVERSHOOT AND BELOW GS DURING APCH TO PITTSBURGH, PA. FATIGUE IS A FACTOR.

Narrative: ON FINAL APCH FOR RWY 32 ILS AT PITTSBURGH INTL, THE CAPT DSNDED BELOW THE 4000 FT PUBLISHED STEP-DOWN ALT PRIOR TO THE STEP-DOWN POINT. I ADVISED HIM HE WAS LOW AND GOING BELOW GLIDE PATH. HE CORRECTED BACK TO THE GS. ABOUT THAT SAME TIME, APCH CTL ALSO ADVISED HIM HE WAS BELOW THE PUBLISHED ALT AT THAT DISTANCE FROM THE ARPT. HE ACKNOWLEDGED, REINTERCEPTED THE GLIDE PATH WELL PRIOR TO THE OM, AND COMPLETED A NORMAL FINAL APCH AND LNDG. WE WERE IN GOOD VMC CONDITIONS AT THE TIME, WITH THE ARPT, GND AND ACFT IN FRONT OF US (ABOUT 4 NM) IN SIGHT. I BELIEVE THERE WERE NUMEROUS CONTRIBUTING FACTORS FOR THIS SIT TO DEVELOP. THE FIRST FACTOR IS FATIGUE. THIS WAS THE LAST DAY OF A VERY LONG 4 DAY TRIP CHARACTERIZED BY LONG DUTY DAYS DUE TO WX DELAYS AND DEVS (TSTMS) FLYING COAST TO COAST EACH DAY, SFO-BWI-LAX-PIT. AS A RESULT, THE SCHEDULED 24+ HR TRIP ENDED UP BEING A 27 HRS 22 MIN TRIP. THIS LAST DAY OF THE TRIP STARTED AT XA15 IN LAX AND ENDED AT XH32 IN PIT. THE LAST LEG WAS SCHEDULED FOR 57 MINS, BUT WAS ACTUALLY 1 HR 43 MINS DUE TO TFC/WX DELAYS FOR TKOF AND LARGE ENRTE DEVS TO AVOID TSTMS AND CUMULO NIMBUS. THE SECOND FACTOR IN THIS SIT WAS THE NON STANDARD ARR DUE TO WX AND TFC ON THE ARR/DSCNT TO PIT. WE WERE FILED AND CLRED FOR THE NESTO ARR TO PIT, BUT PRIOR TO NESTO, WHILE WE WERE DSNDING TO 10000 FT MSL, APCH CTL VECTORED US TO INTERCEPT THE RWY 32 LOC. THIS PUT US ON FINAL APCH AT A HIGHER THAN DESIRED ALT. THE CAPT ELECTED TO SLOW AND CONFIGURE THE ACFT TO EXPEDITE OUR DSCNT TO THE PUBLISHED APCH ALTS. AFTER WE HAD SLOWED TO ABOUT 170 KTS, APCH CTL DIRECTED US TO INCREASE TO 210 KTS. THE CAPT COMPLIED AND WE AGAIN CHANGED THE ACFT CONFIGN TO MATCH THE INCREASED AIRSPD. THE CAPT WAS CONCERNED ABOUT CLOSING ON THE #1 ACFT ON FINAL (WE WERE #2) AND ALSO BEING TOO HIGH AND FAST AT THE OM. THIS IS WHEN HE INADVERTENTLY DSNDED BELOW THE 4000 FT PUBLISHED STEP-DOWN ALT. I BELIEVE HIS FATIGUE COMBINED WITH THE NON STANDARD, SOMEWHAT RUSHED APCH CAUSED HIM TO FOCUS ON HIS AIRSPD AND THE OTHER ACFT TO THE POINT THAT HIS ALT AWARENESS SUFFERED. FORTUNATELY, BOTH MYSELF AND THE APCH CTLR BACKED HIM UP AND CAUGHT THE PROB BEFORE IT BECAME MORE SERIOUS. THE SYS WORKED.

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.