Narrative:

While on approach to runway 14L at iah, early on the morning of 7/xx/88, I was both PIC and PF. We dipped below the floor of the iah TCA between 18 and 15 DME on the 320 degree right. The floor of the TCA in this sector from 20 DME to 15 DME is 4000' MSL, then it drops to 1800' MSL at 15 DME. As my memory serves me, outside of the TCA we were cleared to descend to 4000' on an assigned heading to intercept the runway 14L localizer and a visual approach. At the time the iah VORTAC was OTS. The VORTAC is used to identify all TCA boundaries by distance and radial. The localizer and G/south became alive and we had the runway in sight for a visual, so I continued my descent below 4000' with both visual reference and G/south guidance. The navigation radios were both tuned to the localizer and no DME information was displayed in the cockpit. While descending and slowing through 3700', approach control advised that we had dipped below the TCA floor. At that time power was added, the autoplt disconnected and a climb back to 4000' was initiated. Our descent continued to a low of 3500' before the aircraft began climbing. Reaching 4000' the controller advised us that we were inside the 15 DME sector and cleared to 2000' for the visual. The flight concluded a few mins later with an uneventful landing. At no time was evasive action required to avoid any other aircraft. I believe the contributing factors to the incursion are primarily 1) the crew was completing a duty period that began the previous evening at XX30 pm mdt and had been up all night flying in excess of 7 hours. Secondarily, 2) the nonoperation of the iah VORTAC provided no azimuth or DME information for TCA boundary identify. I don't know what to suggest beyond normally increased vigilance during approach operations to avoid further recurrence of this type of error, especially when both crew members are exhausted and extremely fatigued from flying all night with only 1 or 2 hours in restful sleep in the previous 24 hours. It is difficult to get any restful sleep the afternoon before the trip in order to remain fresh and alert all night.

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Original NASA ASRS Text

Title: ACR MLG INBOUND DESCENDED BELOW THE TCA.

Narrative: WHILE ON APCH TO RWY 14L AT IAH, EARLY ON THE MORNING OF 7/XX/88, I WAS BOTH PIC AND PF. WE DIPPED BELOW THE FLOOR OF THE IAH TCA BTWN 18 AND 15 DME ON THE 320 DEG R. THE FLOOR OF THE TCA IN THIS SECTOR FROM 20 DME TO 15 DME IS 4000' MSL, THEN IT DROPS TO 1800' MSL AT 15 DME. AS MY MEMORY SERVES ME, OUTSIDE OF THE TCA WE WERE CLRED TO DSND TO 4000' ON AN ASSIGNED HDG TO INTERCEPT THE RWY 14L LOC AND A VISUAL APCH. AT THE TIME THE IAH VORTAC WAS OTS. THE VORTAC IS USED TO IDENT ALL TCA BOUNDARIES BY DISTANCE AND RADIAL. THE LOC AND G/S BECAME ALIVE AND WE HAD THE RWY IN SIGHT FOR A VISUAL, SO I CONTINUED MY DSCNT BELOW 4000' WITH BOTH VISUAL REF AND G/S GUIDANCE. THE NAV RADIOS WERE BOTH TUNED TO THE LOC AND NO DME INFO WAS DISPLAYED IN THE COCKPIT. WHILE DSNDING AND SLOWING THROUGH 3700', APCH CTL ADVISED THAT WE HAD DIPPED BELOW THE TCA FLOOR. AT THAT TIME PWR WAS ADDED, THE AUTOPLT DISCONNECTED AND A CLB BACK TO 4000' WAS INITIATED. OUR DSCNT CONTINUED TO A LOW OF 3500' BEFORE THE ACFT BEGAN CLBING. REACHING 4000' THE CTLR ADVISED US THAT WE WERE INSIDE THE 15 DME SECTOR AND CLRED TO 2000' FOR THE VISUAL. THE FLT CONCLUDED A FEW MINS LATER WITH AN UNEVENTFUL LNDG. AT NO TIME WAS EVASIVE ACTION REQUIRED TO AVOID ANY OTHER ACFT. I BELIEVE THE CONTRIBUTING FACTORS TO THE INCURSION ARE PRIMARILY 1) THE CREW WAS COMPLETING A DUTY PERIOD THAT BEGAN THE PREVIOUS EVENING AT XX30 PM MDT AND HAD BEEN UP ALL NIGHT FLYING IN EXCESS OF 7 HRS. SECONDARILY, 2) THE NONOPERATION OF THE IAH VORTAC PROVIDED NO AZIMUTH OR DME INFO FOR TCA BOUNDARY IDENT. I DON'T KNOW WHAT TO SUGGEST BEYOND NORMALLY INCREASED VIGILANCE DURING APCH OPS TO AVOID FURTHER RECURRENCE OF THIS TYPE OF ERROR, ESPECIALLY WHEN BOTH CREW MEMBERS ARE EXHAUSTED AND EXTREMELY FATIGUED FROM FLYING ALL NIGHT WITH ONLY 1 OR 2 HRS IN RESTFUL SLEEP IN THE PREVIOUS 24 HRS. IT IS DIFFICULT TO GET ANY RESTFUL SLEEP THE AFTERNOON BEFORE THE TRIP IN ORDER TO REMAIN FRESH AND ALERT ALL NIGHT.

Data retrieved from NASA's ASRS site as of August 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.