Narrative:

While en route to sba destination, conditions went from clear to ceiling obscured, 100 overcast, RVR 1200, conditions not forecast during the briefing I received 3 hours prior to departure. On arrival I decided to shoot the approach. I showed my passenger, who although not a licensed pilot, has had some flight instruction and exposure to previous IFR trips, what the approach lights would look like, and assigned the task of looking for them, also explaining the elements of the approach and what would determine whether we landed or missed. The approach went smoothly aside from an inadvertent descent in VMC below GS intercept altitude by about 200 ft, about which approach control provided a gentle reminder. During the descent through the clouds (tops 800), I concentrated on INS, calling out altitudes at 100 ft intervals, ended the descent at 220 ft MSL and reconfigured for climb. Shortly after passenger suddenly yelled about going down, grabbed yoke and put aircraft into steep nose-up pitch, setting off stall horn, and then into a dive. While fighting for yoke I finally got passenger to let go, recovered a normal attitude and resumed climb out, all in essentially 0, 0 conditions. I am unaware of any problems which existed before passenger took the yoke but don't remember the 10 seconds or so before all this started. However I am sure that if we hadn't gained some altitude since beginning the missed, recovery would have been almost impossible given the extreme nature of the maneuvers which were induced. I received no communication from the tower or subsequently from approach control about this. They were probably unaware of what was happening as the elapsed time was very short and sampling by radar may not have shown any particularly unusual altitudes. I presume passenger was a victim of spatial disorientation and stress. I also presume that events such as this are rare, but that stress during such an event is probably not, either on the part of the passenger or pilot. Stress might have been reduced if I had continued to verbalize during missed approach segment. In future I will communicate more during the entire procedure. Perhaps a formal program for frequent passenger might help, analogous to AOPA's pinch hitter course, educating then about procedures and equipping them to help during various phases of an IFR flight. I have never been through a more terrifying experience.

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Original NASA ASRS Text

Title: SMA PLT CONDUCTING ILS APCH WITH WX BELOW MINIMUMS HAS PASSENGER GRAB CONTROL. LOSS OF CONTROL ENSUES.

Narrative: WHILE ENRTE TO SBA DEST, CONDITIONS WENT FROM CLR TO CEILING OBSCURED, 100 OVCST, RVR 1200, CONDITIONS NOT FORECAST DURING THE BRIEFING I RECEIVED 3 HRS PRIOR TO DEP. ON ARR I DECIDED TO SHOOT THE APCH. I SHOWED MY PAX, WHO ALTHOUGH NOT A LICENSED PLT, HAS HAD SOME FLT INSTRUCTION AND EXPOSURE TO PREVIOUS IFR TRIPS, WHAT THE APCH LIGHTS WOULD LOOK LIKE, AND ASSIGNED THE TASK OF LOOKING FOR THEM, ALSO EXPLAINING THE ELEMENTS OF THE APCH AND WHAT WOULD DETERMINE WHETHER WE LANDED OR MISSED. THE APCH WENT SMOOTHLY ASIDE FROM AN INADVERTENT DSCNT IN VMC BELOW GS INTERCEPT ALT BY ABOUT 200 FT, ABOUT WHICH APCH CTL PROVIDED A GENTLE REMINDER. DURING THE DSCNT THROUGH THE CLOUDS (TOPS 800), I CONCENTRATED ON INS, CALLING OUT ALTS AT 100 FT INTERVALS, ENDED THE DSCNT AT 220 FT MSL AND RECONFIGURED FOR CLB. SHORTLY AFTER PAX SUDDENLY YELLED ABOUT GOING DOWN, GRABBED YOKE AND PUT ACFT INTO STEEP NOSE-UP PITCH, SETTING OFF STALL HORN, AND THEN INTO A DIVE. WHILE FIGHTING FOR YOKE I FINALLY GOT PAX TO LET GO, RECOVERED A NORMAL ATTITUDE AND RESUMED CLBOUT, ALL IN ESSENTIALLY 0, 0 CONDITIONS. I AM UNAWARE OF ANY PROBS WHICH EXISTED BEFORE PAX TOOK THE YOKE BUT DON'T REMEMBER THE 10 SECS OR SO BEFORE ALL THIS STARTED. HOWEVER I AM SURE THAT IF WE HADN'T GAINED SOME ALT SINCE BEGINNING THE MISSED, RECOVERY WOULD HAVE BEEN ALMOST IMPOSSIBLE GIVEN THE EXTREME NATURE OF THE MANEUVERS WHICH WERE INDUCED. I RECEIVED NO COM FROM THE TWR OR SUBSEQUENTLY FROM APCH CTL ABOUT THIS. THEY WERE PROBABLY UNAWARE OF WHAT WAS HAPPENING AS THE ELAPSED TIME WAS VERY SHORT AND SAMPLING BY RADAR MAY NOT HAVE SHOWN ANY PARTICULARLY UNUSUAL ALTS. I PRESUME PAX WAS A VICTIM OF SPATIAL DISORIENTATION AND STRESS. I ALSO PRESUME THAT EVENTS SUCH AS THIS ARE RARE, BUT THAT STRESS DURING SUCH AN EVENT IS PROBABLY NOT, EITHER ON THE PART OF THE PAX OR PLT. STRESS MIGHT HAVE BEEN REDUCED IF I HAD CONTINUED TO VERBALIZE DURING MISSED APCH SEGMENT. IN FUTURE I WILL COMMUNICATE MORE DURING THE ENTIRE PROC. PERHAPS A FORMAL PROGRAM FOR FREQUENT PAX MIGHT HELP, ANALOGOUS TO AOPA'S PINCH HITTER COURSE, EDUCATING THEN ABOUT PROCS AND EQUIPPING THEM TO HELP DURING VARIOUS PHASES OF AN IFR FLT. I HAVE NEVER BEEN THROUGH A MORE TERRIFYING EXPERIENCE.

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.