Medium large transport on ILS approach has sudden nose down pitch.

Attributes
ACN	243550
Time
Date	199306
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	agl bound lower : 800 agl bound upper : 800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : ord
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 10000 flight time type : 1000
ASRS Report	243550
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical altitude deviation : overshoot other anomaly other anomaly other other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

While on ILS approach to 9L at ord, in an medium large transport aircraft, autoplts (both) engaged localizer and GS captured, the aircraft did an aggressive nose down pitch, uncommanded, first officer flying. Recovered by disconnecting autoplt. Maximum GS deviation of approximately 1 DOT. Suspect possibly related to aircraft departing 32L crossing final for 9L while climbing out. Captain was busy at the time checking hold short ability, as just before this the tower surprised both of us with a hold short landing clearance. We should have been given much more notice as our company required consulting a chart. Aircraft followed the received GS signal.

Original NASA ASRS Text

Title: MLG ON ILS APCH HAS SUDDEN NOSE DOWN PITCH.

Narrative: WHILE ON ILS APCH TO 9L AT ORD, IN AN MLG ACFT, AUTOPLTS (BOTH) ENGAGED LOC AND GS CAPTURED, THE ACFT DID AN AGGRESSIVE NOSE DOWN PITCH, UNCOMMANDED, FO FLYING. RECOVERED BY DISCONNECTING AUTOPLT. MAX GS DEV OF APPROX 1 DOT. SUSPECT POSSIBLY RELATED TO ACFT DEPARTING 32L XING FINAL FOR 9L WHILE CLBING OUT. CAPT WAS BUSY AT THE TIME CHKING HOLD SHORT ABILITY, AS JUST BEFORE THIS THE TWR SURPRISED BOTH OF US WITH A HOLD SHORT LNDG CLRNC. WE SHOULD HAVE BEEN GIVEN MUCH MORE NOTICE AS OUR COMPANY REQUIRED CONSULTING A CHART. ACFT FOLLOWED THE RECEIVED GS SIGNAL.

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.