Air carrier crew distracted with new procedure and TCAS ii descended below assigned altitude.

Attributes
ACN	168905
Time
Date	199101
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : day
State Reference	OH
Altitude	msl bound lower : 10700 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute airway : zid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 12000 flight time type : 4000
ASRS Report	168905
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot incursion : runway non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

This refers to flight ewr to day on 1/thu/91. Subject is a potential altitude deviation. 3 distrs are apparent during the sequence: TCAS, a new piece of equipment; a newly introduced procedure to enforce altitude awareness; and a procedure cockpit announcement. The new crew procedure requires each pilot to point to and verbally acknowledge the insertion of each new altitude in the altitude alerter. The procedure was being diligently adhered to. The first officer was PF. The flight was cleared to descend to 11000' by mecan intersection, an initial approach fix for day. 30 mi short of mecan was directed to stop the descent at 12000'. The captain busied himself with the TCAS ii trying to locate the apparently traffic conflict. Moments later the flight was cleared to 11000'. The first officer set in 10000' (vs 11000'). The captain acknowledged receipt of the new altitude. The altitude alerter is in the far right-hand side of the center console and not plainly visible from the left side. Captain's attention went back again to the TCAS ii and then to make a passenger announcement to prepare the cabin for landing. Captain saw aircraft descend through 11000'. Looking carefully at the altitude alerter saw 10000'. Mentally knew 11000' was correct, but new procedure momentarily convinced him that 10000' must be correct. At 10700' finally exerted himself and directed the first officer to stop the descent and go back up to 11000'. At that point ATC cut in questioning the altitude and confirming the captain's opinion. End result was a momentary deviation of 300-400'. Note here the time frame of 5 mins, an original descent, new altitude change and return to original altitude. Throw in 2 extraneous procedure items, which consume time, and a new gadget (TCAS) which created an additional diversion of time. Additional procedures are not necessarily a magic pill for solving problems. But they do evaporate time for the pilots in what is a very time constrained environment for a 2-M crew.

Original NASA ASRS Text

Title: ACR CREW DISTRACTED WITH NEW PROC AND TCAS II DESCENDED BELOW ASSIGNED ALT.

Narrative: THIS REFERS TO FLT EWR TO DAY ON 1/THU/91. SUBJECT IS A POTENTIAL ALT DEVIATION. 3 DISTRS ARE APPARENT DURING THE SEQUENCE: TCAS, A NEW PIECE OF EQUIP; A NEWLY INTRODUCED PROC TO ENFORCE ALT AWARENESS; AND A PROC COCKPIT ANNOUNCEMENT. THE NEW CREW PROC REQUIRES EACH PLT TO POINT TO AND VERBALLY ACKNOWLEDGE THE INSERTION OF EACH NEW ALT IN THE ALT ALERTER. THE PROC WAS BEING DILIGENTLY ADHERED TO. THE F/O WAS PF. THE FLT WAS CLRED TO DSND TO 11000' BY MECAN INTXN, AN INITIAL APCH FIX FOR DAY. 30 MI SHORT OF MECAN WAS DIRECTED TO STOP THE DSNT AT 12000'. THE CAPT BUSIED HIMSELF WITH THE TCAS II TRYING TO LOCATE THE APPARENTLY TFC CONFLICT. MOMENTS LATER THE FLT WAS CLRED TO 11000'. THE F/O SET IN 10000' (VS 11000'). THE CAPT ACKNOWLEDGED RECEIPT OF THE NEW ALT. THE ALT ALERTER IS IN THE FAR RIGHT-HAND SIDE OF THE CENTER CONSOLE AND NOT PLAINLY VISIBLE FROM THE LEFT SIDE. CAPT'S ATTN WENT BACK AGAIN TO THE TCAS II AND THEN TO MAKE A PAX ANNOUNCEMENT TO PREPARE THE CABIN FOR LNDG. CAPT SAW ACFT DSND THROUGH 11000'. LOOKING CAREFULLY AT THE ALT ALERTER SAW 10000'. MENTALLY KNEW 11000' WAS CORRECT, BUT NEW PROC MOMENTARILY CONVINCED HIM THAT 10000' MUST BE CORRECT. AT 10700' FINALLY EXERTED HIMSELF AND DIRECTED THE F/O TO STOP THE DSNT AND GO BACK UP TO 11000'. AT THAT POINT ATC CUT IN QUESTIONING THE ALT AND CONFIRMING THE CAPT'S OPINION. END RESULT WAS A MOMENTARY DEVIATION OF 300-400'. NOTE HERE THE TIME FRAME OF 5 MINS, AN ORIGINAL DSNT, NEW ALT CHANGE AND RETURN TO ORIGINAL ALT. THROW IN 2 EXTRANEOUS PROC ITEMS, WHICH CONSUME TIME, AND A NEW GADGET (TCAS) WHICH CREATED AN ADDITIONAL DIVERSION OF TIME. ADDITIONAL PROCS ARE NOT NECESSARILY A MAGIC PILL FOR SOLVING PROBS. BUT THEY DO EVAPORATE TIME FOR THE PLTS IN WHAT IS A VERY TIME CONSTRAINED ENVIRONMENT FOR A 2-M CREW.

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.