B737 flight crew incorrectly operate autoplt resulting in an altitude overshoot.

Attributes
ACN	526975
Time
Date	200110
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : pmd.vortac
State Reference	CA
Altitude	msl bound lower : 16000 msl bound upper : 16800
Environment
Flight Conditions	VMC
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : ns
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 6000
ASRS Report	526975
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 193 flight time total : 4000 flight time type : 1500
ASRS Report	526976
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure non adherence : clearance
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa
Resolutory Action	controller : issued new clearance controller : issued advisory flight crew : overrode automation flight crew : became reoriented
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were level at 13000 ft MSL and accelerating to en route speed. ZLA gave us a clearance to climb and maintain 16000 ft MSL. I started a climb to 16000 ft and continued to accelerate. The 'a' channel autoplt was being used with control column inputs being used to maneuver the aircraft. I was returning my navigation radios when I noticed the airplane going through 16000 ft MSL. The altitude acquire mode appeared to be engaged but the autoplt had not captured the assigned altitude 16000 ft MSL. I disengaged the autoplt, stopped the climb and initiated the descent back to 16000 ft MSL. We reached about 16800 ft MSL before I was able to stop the climb. Center asked us about our altitude and told us we had been assigned 16000 ft MSL. He then gave us a clearance to maintain 17000 ft MSL, which we did. I do not know if the rate of climb was too high for the autoplt to capture the assigned altitude or if I inadvertently applied yoke pressure and caused it to miss the altitude. In any case, I should have paid more attention to the leveloff process. I could have avoided my altitude deviation. The autoplt acted normally for the rest of the flight. Supplemental information from acn 526976: passing 15000 ft with a 5000 FPM climb rate, autoplt went to 'act' acquire mode, but failed to lower the nose.

Original NASA ASRS Text

Title: B737 FLC INCORRECTLY OPERATE AUTOPLT RESULTING IN AN ALT OVERSHOOT.

Narrative: WE WERE LEVEL AT 13000 FT MSL AND ACCELERATING TO ENRTE SPD. ZLA GAVE US A CLRNC TO CLB AND MAINTAIN 16000 FT MSL. I STARTED A CLB TO 16000 FT AND CONTINUED TO ACCELERATE. THE 'A' CHANNEL AUTOPLT WAS BEING USED WITH CTL COLUMN INPUTS BEING USED TO MANEUVER THE ACFT. I WAS RETURNING MY NAV RADIOS WHEN I NOTICED THE AIRPLANE GOING THROUGH 16000 FT MSL. THE ALT ACQUIRE MODE APPEARED TO BE ENGAGED BUT THE AUTOPLT HAD NOT CAPTURED THE ASSIGNED ALT 16000 FT MSL. I DISENGAGED THE AUTOPLT, STOPPED THE CLB AND INITIATED THE DSCNT BACK TO 16000 FT MSL. WE REACHED ABOUT 16800 FT MSL BEFORE I WAS ABLE TO STOP THE CLB. CTR ASKED US ABOUT OUR ALT AND TOLD US WE HAD BEEN ASSIGNED 16000 FT MSL. HE THEN GAVE US A CLRNC TO MAINTAIN 17000 FT MSL, WHICH WE DID. I DO NOT KNOW IF THE RATE OF CLB WAS TOO HIGH FOR THE AUTOPLT TO CAPTURE THE ASSIGNED ALT OR IF I INADVERTENTLY APPLIED YOKE PRESSURE AND CAUSED IT TO MISS THE ALT. IN ANY CASE, I SHOULD HAVE PAID MORE ATTN TO THE LEVELOFF PROCESS. I COULD HAVE AVOIDED MY ALTDEV. THE AUTOPLT ACTED NORMALLY FOR THE REST OF THE FLT. SUPPLEMENTAL INFO FROM ACN 526976: PASSING 15000 FT WITH A 5000 FPM CLB RATE, AUTOPLT WENT TO 'ACT' ACQUIRE MODE, BUT FAILED TO LOWER THE NOSE.

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.