LNDG UNDERSHOT WHILE PRACTICING SHORT FIELD LNDGS. TRAINING IN PROGRESS.

Narrative

AS MY STUDENT PRACTICED SHORT-FIELD LNDGS AT PALO ALTO; WHILE I WAS INSTRUCTING; THE FOLLOWING EVENT OCCURRED: STUDENT WAS HIGH ON APCH PATH BUT LOW ON AIRSPD SO I INSTRUCTED HIM TO REDUCE PWR AND LOWER THE NOSE. HE REDUCED PWR; BUT DID NOT LOWER NOSE ENOUGH TO GAIN ENOUGH AIRSPD. HOWEVER; WE WERE STILL NEAR RECOMMENDED SHORT FIELD APCH SPD. AS WE GOT CLOSER TO THE RWY HE GOT SLOWER SO I REACHED TO APPLY PWR; BUT AS I REACHED HE SUDDENLY YANKED BACK ON THE YOKE CAUSING THE ACFT TO; IN FACT; STALL IN. WE WERE PROBABLY AT 2-4 FT OFF THE GND AS THIS OCCURRED. I AM STILL NOT SURE IF WE MADE THE END OF THE RWY; OR IF THE MAINS CLIPPED THE GRASS JUST PRIOR TO THE RWY. THE WHOLE EVENT HAPPENED WITH SUCH RAPIDITY AND IN SUCH AN UNEXPECTED MANNER I WAS UNABLE TO CORRECT THE SIT SOON ENOUGH. I THINK THAT IN FUTURE I WILL TAKE THE FOLLOWING STEPS TO TRY TO PREVENT THIS SIT OCCURRING AGAIN: 1) DEMONSTRATE PROC MORE THAN ONCE PRIOR TO LETTING STUDENT TRY IT BY HIM/HERSELF. 2) KEEP MY HANDS RIGHT ON CTLS FOR FIRST COUPLE OF STUDENT ATTEMPTS. 3) TRY TO BE EVEN QUICKER WITH REACTIONS. UNFORTUNATELY; I BELIEVE THAT IN THIS PARTICULAR SIT; EVEN IF I WAS FULLY EXPECTING THE EVENT IT WOULD HAVE BEEN ALMOST IMPOSSIBLE TO CORRECT THE SIT; AS IT HAPPENED SO QUICKLY AND SO CLOSE TO THE GND. THERE WAS NO DAMAGE TO THE ACFT OR OCCUPANTS; AND I WAS UNABLE TO ASCERTAIN ANYTHING MORE BY INSPECTION OF THE APCH END OF THE RWY.