<< >> NASA ASRS Report 90096, July 1988

Assigned to maintain 160 IAS to outer marker. Autoplt malfunction causes rapid climb and speed decrease to 120 IAS.

Attributes
ACN	90096
Time
Date	198807
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bur
State Reference	CA
Altitude	msl bound lower : 3500 msl bound upper : 3500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bur
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 1500
ASRS Report	90096
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

I was outside the OM at 3500', was cleared for the runway 7 ILS approach and asked to maintain 160 KTS and 3500' to OM. Aircraft was being flown by autoplt. I selected 'navigation' on autoplt head to intercept localizer and 'altitude' altitude hold was on already. However aircraft started rapid descent. I retrimmed the autoplt to regain altitude, autoplt went into very steep climb, aircraft lost speed to 120 KTS. I disconnected the autoplt at this point, the aircraft was totally out of trim. I manually retrimmed the aircraft as soon as possible and manually flew the approach. Bur approach became very upset about the speed deviation and asked if I could maintain 120 KTS. I explained that my autoplt system had in a split second almost put the aircraft into an unusual altitude and that speed and altitude was lost during recovery.

Related reports:

• Cirrus SR22 pilot during climb has the autoplt malfunction a...
• A B767 flight crew experience a malfunction in the rudder tr...
• Flight crew of a B737 climbed above assigned cruising altitu...
• A ce-500 on the teb 8 departure failed to capture 6;000 ft b...
• An MD80 overshoots its assigned altitude during climb. Crew ...
• Flight crew failed to note autoplt malfunction resulting in ...

	Enter your search terms Submit search form
	Web www.37000feet.com

Original NASA ASRS Text

Title: ASSIGNED TO MAINTAIN 160 IAS TO OUTER MARKER. AUTOPLT MALFUNCTION CAUSES RAPID CLIMB AND SPEED DECREASE TO 120 IAS.

Narrative: I WAS OUTSIDE THE OM AT 3500', WAS CLRED FOR THE RWY 7 ILS APCH AND ASKED TO MAINTAIN 160 KTS AND 3500' TO OM. ACFT WAS BEING FLOWN BY AUTOPLT. I SELECTED 'NAV' ON AUTOPLT HEAD TO INTERCEPT LOC AND 'ALT' ALT HOLD WAS ON ALREADY. HOWEVER ACFT STARTED RAPID DSCNT. I RETRIMMED THE AUTOPLT TO REGAIN ALT, AUTOPLT WENT INTO VERY STEEP CLB, ACFT LOST SPD TO 120 KTS. I DISCONNECTED THE AUTOPLT AT THIS POINT, THE ACFT WAS TOTALLY OUT OF TRIM. I MANUALLY RETRIMMED THE ACFT ASAP AND MANUALLY FLEW THE APCH. BUR APCH BECAME VERY UPSET ABOUT THE SPD DEV AND ASKED IF I COULD MAINTAIN 120 KTS. I EXPLAINED THAT MY AUTOPLT SYS HAD IN A SPLIT SEC ALMOST PUT THE ACFT INTO AN UNUSUAL ALT AND THAT SPD AND ALT WAS LOST DURING RECOVERY.

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.