Narrative:

While being vectored to final (runway 22, ord) and descending to 7000 ft MSL and slowing to 210 KIAS, we received a TA from the TCASII. This alert redirected our attention outside the airplane during the final 200 ft to level off. The proximity of the aircraft combined with our descent rate (plus the climb rate of the other aircraft) caused the TA to become an RA. This distraction drew our attention completely away from the leveloff at 7000 ft MSL. The deviation was noted passing 6750 ft MSL and immediate power and pitch increase were applied. Maximum altitude deviation 300 ft low (6700 ft MSL). The aircraft traffic was sighted just prior to the deviation recognition. Safety was not an issue (ie, near miss) -- the other aircraft appeared to be approximately 1 mi away. Although training in the back seat (flight engineer) was being conducted, this was not a contributing factor. This was the first flight of the day after a 14 hour layover. Rest/fatigue was also not a factor. The coincidental TA/RA at leveloff and speed reduction redirected our attention away from flying the aircraft. Supplemental information from acn 395471: approaching 7000 ft we got a TCASII RA to 'monitor vertical descent.' the TCASII screen indicated an airplane about 2 mi in front of us level at 6000 ft. While looking at the screen the copilot descended below 7000 ft and the RA continued. Seeing that the copilot was below the assigned altitude the captain told the copilot to maintain 7000 ft. At the same time chicago approach called and stated 'maintain 7000 ft.' the captain remarked 'roger, maintain 7000 ft.' the copilot stopped the descent and bottomed out at 6700 ft. He quickly corrected the altitude back to 7000 ft.

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Original NASA ASRS Text

Title: AN ACR B727 FLC DSNDS BELOW THE ASSIGNED ALT WHEN THE FO BECAME DISTRACTED BY THE TCASII'S TA AND LATER RECEIVES AN RA.

Narrative: WHILE BEING VECTORED TO FINAL (RWY 22, ORD) AND DSNDING TO 7000 FT MSL AND SLOWING TO 210 KIAS, WE RECEIVED A TA FROM THE TCASII. THIS ALERT REDIRECTED OUR ATTN OUTSIDE THE AIRPLANE DURING THE FINAL 200 FT TO LEVEL OFF. THE PROX OF THE ACFT COMBINED WITH OUR DSCNT RATE (PLUS THE CLB RATE OF THE OTHER ACFT) CAUSED THE TA TO BECOME AN RA. THIS DISTR DREW OUR ATTN COMPLETELY AWAY FROM THE LEVELOFF AT 7000 FT MSL. THE DEV WAS NOTED PASSING 6750 FT MSL AND IMMEDIATE PWR AND PITCH INCREASE WERE APPLIED. MAX ALTDEV 300 FT LOW (6700 FT MSL). THE ACFT TFC WAS SIGHTED JUST PRIOR TO THE DEV RECOGNITION. SAFETY WAS NOT AN ISSUE (IE, NEAR MISS) -- THE OTHER ACFT APPEARED TO BE APPROX 1 MI AWAY. ALTHOUGH TRAINING IN THE BACK SEAT (FE) WAS BEING CONDUCTED, THIS WAS NOT A CONTRIBUTING FACTOR. THIS WAS THE FIRST FLT OF THE DAY AFTER A 14 HR LAYOVER. REST/FATIGUE WAS ALSO NOT A FACTOR. THE COINCIDENTAL TA/RA AT LEVELOFF AND SPD REDUCTION REDIRECTED OUR ATTN AWAY FROM FLYING THE ACFT. SUPPLEMENTAL INFO FROM ACN 395471: APCHING 7000 FT WE GOT A TCASII RA TO 'MONITOR VERT DSCNT.' THE TCASII SCREEN INDICATED AN AIRPLANE ABOUT 2 MI IN FRONT OF US LEVEL AT 6000 FT. WHILE LOOKING AT THE SCREEN THE COPLT DSNDED BELOW 7000 FT AND THE RA CONTINUED. SEEING THAT THE COPLT WAS BELOW THE ASSIGNED ALT THE CAPT TOLD THE COPLT TO MAINTAIN 7000 FT. AT THE SAME TIME CHICAGO APCH CALLED AND STATED 'MAINTAIN 7000 FT.' THE CAPT REMARKED 'ROGER, MAINTAIN 7000 FT.' THE COPLT STOPPED THE DSCNT AND BOTTOMED OUT AT 6700 FT. HE QUICKLY CORRECTED THE ALT BACK TO 7000 FT.

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.