A coupled autoplt pitched up following the brief capture of a false GS as it biased upward.

Attributes
ACN	656860
Time
Date	200505
Place
Locale Reference	airport : zzz.airport
State Reference	US
Environment
Flight Conditions	IMC
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	656860
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical altitude deviation : crossing restriction not met altitude deviation : excursion from assigned altitude non adherence : published procedure other anomaly other
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated flight crew : regained aircraft control
Consequence	other
Supplementary
Problem Areas	Navigational Facility Aircraft Company Flight Crew Human Performance
Primary Problem	Navigational Facility

Narrative:

Recently; while making an ILS approach in IMC; I had an aircraft pitch up event occur as a result of the first officer selecting approach instead of VOR/localizer. This occurred after being cleared for the approach via vectors. In this case we were 12-13 mi out and just about to capture the localizer when a false GS situation occurred. The GS pointer had been at the top of the indicator and then quickly centered briefly only to go back to the top of the indicator. However; it had been centered long enough for the autoplt to capture it and then follow it back up to the top of the indicator. A rather alarming aircraft pitch up was the result -- not good close to the ground in IMC! When I was first hired; I recall being instructed to always select VOR/localizer first and then when (and only when) the localizer was captured and an obviously correct GS was available -- select approach. The concern was that GS capture could occur prior to localizer capture and the aircraft would start to descend. That concern is still mentioned in the fom (page 3.16.5). However; if it is not a concern (as obviously it was not in the situation above) the pilot is instructed to go ahead and select approach right away. I had been using the old method during upgrade training; but was corrected and instructed to go ahead and select approach right away. Dutifully; I was doing this out on the line until a scenario much like the one described above (fortunately in VMC) occurred. I elected to revert back to the old method from then on. Nevertheless; it appears that new hires are being instructed to use the select approach right away method and pitch ups are occurring. If it has happened to me twice; it has probably happened many times throughout our system. Obviously; the above described scenario could present a potentially dangerous situation some dark and stormy night. Based on what I have seen out on the line; my suggestion is that the recommended procedure be revisited for safety's sake.

Original NASA ASRS Text

Title: A COUPLED AUTOPLT PITCHED UP FOLLOWING THE BRIEF CAPTURE OF A FALSE GS AS IT BIASED UPWARD.

Narrative: RECENTLY; WHILE MAKING AN ILS APCH IN IMC; I HAD AN ACFT PITCH UP EVENT OCCUR AS A RESULT OF THE FO SELECTING APCH INSTEAD OF VOR/LOC. THIS OCCURRED AFTER BEING CLRED FOR THE APCH VIA VECTORS. IN THIS CASE WE WERE 12-13 MI OUT AND JUST ABOUT TO CAPTURE THE LOC WHEN A FALSE GS SIT OCCURRED. THE GS POINTER HAD BEEN AT THE TOP OF THE INDICATOR AND THEN QUICKLY CTRED BRIEFLY ONLY TO GO BACK TO THE TOP OF THE INDICATOR. HOWEVER; IT HAD BEEN CTRED LONG ENOUGH FOR THE AUTOPLT TO CAPTURE IT AND THEN FOLLOW IT BACK UP TO THE TOP OF THE INDICATOR. A RATHER ALARMING ACFT PITCH UP WAS THE RESULT -- NOT GOOD CLOSE TO THE GND IN IMC! WHEN I WAS FIRST HIRED; I RECALL BEING INSTRUCTED TO ALWAYS SELECT VOR/LOC FIRST AND THEN WHEN (AND ONLY WHEN) THE LOC WAS CAPTURED AND AN OBVIOUSLY CORRECT GS WAS AVAILABLE -- SELECT APCH. THE CONCERN WAS THAT GS CAPTURE COULD OCCUR PRIOR TO LOC CAPTURE AND THE ACFT WOULD START TO DSND. THAT CONCERN IS STILL MENTIONED IN THE FOM (PAGE 3.16.5). HOWEVER; IF IT IS NOT A CONCERN (AS OBVIOUSLY IT WAS NOT IN THE SIT ABOVE) THE PLT IS INSTRUCTED TO GO AHEAD AND SELECT APCH RIGHT AWAY. I HAD BEEN USING THE OLD METHOD DURING UPGRADE TRAINING; BUT WAS CORRECTED AND INSTRUCTED TO GO AHEAD AND SELECT APCH RIGHT AWAY. DUTIFULLY; I WAS DOING THIS OUT ON THE LINE UNTIL A SCENARIO MUCH LIKE THE ONE DESCRIBED ABOVE (FORTUNATELY IN VMC) OCCURRED. I ELECTED TO REVERT BACK TO THE OLD METHOD FROM THEN ON. NEVERTHELESS; IT APPEARS THAT NEW HIRES ARE BEING INSTRUCTED TO USE THE SELECT APCH RIGHT AWAY METHOD AND PITCH UPS ARE OCCURRING. IF IT HAS HAPPENED TO ME TWICE; IT HAS PROBABLY HAPPENED MANY TIMES THROUGHOUT OUR SYS. OBVIOUSLY; THE ABOVE DESCRIBED SCENARIO COULD PRESENT A POTENTIALLY DANGEROUS SIT SOME DARK AND STORMY NIGHT. BASED ON WHAT I HAVE SEEN OUT ON THE LINE; MY SUGGESTION IS THAT THE RECOMMENDED PROC BE REVISITED FOR SAFETY'S SAKE.

Data retrieved from NASA's ASRS site as of January 2009 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.