Altitude deviation in descent.

Attributes
ACN	170609
Time
Date	199102
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : air
State Reference	OH
Altitude	msl bound lower : 27500 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other descent other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain instruction : trainee
Qualification	pilot : flight engineer pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 75 flight time total : 10000 flight time type : 3000
ASRS Report	170601
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer observation : company check pilot oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 25000 flight time type : 5000
ASRS Report	170520
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot conflict : airborne less severe non adherence : required legal separation non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

We were cleared by the center from FL310 to FL290 and then to FL280. The automatic-altitude capture feature of the autoplt failed to capture at FL280 after being armed. The altitude alert device sounded (tone) and simultaneously were notified by the controller. We immediately manually climbed the aircraft to FL280. Another flight in the area (air carrier) was visible at all times and passed off our left at approximately 500' below and 3 mi horizontal. Contributing factors seemed to be: 1) altitude warning feature of the autoplt/alert device set at 500' instead of 250' (would have prevented alarm for ATC). 2) failure of autoplt to automatically capture the altitude after being armed. 3) I was receiving line training (IOE) as a new captain. 4) timely notification by the ATC controller (a positive). 5) another aircraft in the vicinity possibly triggering ATC alert. No evasive action was taken in the incident, nor was any needed, in my opinion.

Original NASA ASRS Text

Title: ALT DEVIATION IN DESCENT.

Narrative: WE WERE CLRED BY THE CENTER FROM FL310 TO FL290 AND THEN TO FL280. THE AUTO-ALT CAPTURE FEATURE OF THE AUTOPLT FAILED TO CAPTURE AT FL280 AFTER BEING ARMED. THE ALT ALERT DEVICE SOUNDED (TONE) AND SIMULTANEOUSLY WERE NOTIFIED BY THE CTLR. WE IMMEDIATELY MANUALLY CLBED THE ACFT TO FL280. ANOTHER FLT IN THE AREA (ACR) WAS VISIBLE AT ALL TIMES AND PASSED OFF OUR LEFT AT APPROX 500' BELOW AND 3 MI HORIZ. CONTRIBUTING FACTORS SEEMED TO BE: 1) ALT WARNING FEATURE OF THE AUTOPLT/ALERT DEVICE SET AT 500' INSTEAD OF 250' (WOULD HAVE PREVENTED ALARM FOR ATC). 2) FAILURE OF AUTOPLT TO AUTOMATICALLY CAPTURE THE ALT AFTER BEING ARMED. 3) I WAS RECEIVING LINE TRNING (IOE) AS A NEW CAPT. 4) TIMELY NOTIFICATION BY THE ATC CTLR (A POSITIVE). 5) ANOTHER ACFT IN THE VICINITY POSSIBLY TRIGGERING ATC ALERT. NO EVASIVE ACTION WAS TAKEN IN THE INCIDENT, NOR WAS ANY NEEDED, IN MY OPINION.

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.