Autothrottles advanced on touchdown resulting in an large transport bouncing back into the air momen...

Attributes
ACN	336662
Time
Date	199605
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den
State Reference	CO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 230 flight time total : 15000 flight time type : 2000
ASRS Report	336662
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

A very short flight (20 mins) delayed 5 mins to defer an inoperative TCASII. An FAA inspector on jumpseat. High workload environment with numerous TA's given by ATC due to outbound den traffic. First officer made visual hand flown approach and landing. On touchdown, throttles advanced and speed lever disarmed, aircraft skipped slightly but touched down again before first officer brought throttles to idle and then reverse, at which point the speed brakes automatic deployed. This is consistent with having the autothrottles engaged at touchdown and is not a big deal problem except for the unexpected surprise, and this does eat up some runway while a recovery is made to normal. The first officer believes he disengaged the autothrottles at the same time as the autoplt. However, we probably used flechette during an ensuing altitude change which would have reengaged the autothrottles at a time when throttles were at idle, thus no sensory input. Thereafter, autothrottle movement might match pilot inputs and pilot would not be aware of reengagement. This is, I think, one of the bad aspects of this particular autoflt system. Autothrottle arm switch has to be turned off to prevent this from occurring, but then would not have autothrottles in case of a missed approach.

Original NASA ASRS Text

Title: AUTOTHROTTLES ADVANCED ON TOUCHDOWN RESULTING IN AN LGT BOUNCING BACK INTO THE AIR MOMENTARILY. HOWEVER, IT DID COME BACK DOWN PRIOR TO THE FO PUTTING THE THROTTLES TO FLT IDLE.

Narrative: A VERY SHORT FLT (20 MINS) DELAYED 5 MINS TO DEFER AN INOP TCASII. AN FAA INSPECTOR ON JUMPSEAT. HIGH WORKLOAD ENVIRONMENT WITH NUMEROUS TA'S GIVEN BY ATC DUE TO OUTBOUND DEN TFC. FO MADE VISUAL HAND FLOWN APCH AND LNDG. ON TOUCHDOWN, THROTTLES ADVANCED AND SPD LEVER DISARMED, ACFT SKIPPED SLIGHTLY BUT TOUCHED DOWN AGAIN BEFORE FO BROUGHT THROTTLES TO IDLE AND THEN REVERSE, AT WHICH POINT THE SPD BRAKES AUTO DEPLOYED. THIS IS CONSISTENT WITH HAVING THE AUTOTHROTTLES ENGAGED AT TOUCHDOWN AND IS NOT A BIG DEAL PROB EXCEPT FOR THE UNEXPECTED SURPRISE, AND THIS DOES EAT UP SOME RWY WHILE A RECOVERY IS MADE TO NORMAL. THE FO BELIEVES HE DISENGAGED THE AUTOTHROTTLES AT THE SAME TIME AS THE AUTOPLT. HOWEVER, WE PROBABLY USED FLECHETTE DURING AN ENSUING ALT CHANGE WHICH WOULD HAVE REENGAGED THE AUTOTHROTTLES AT A TIME WHEN THROTTLES WERE AT IDLE, THUS NO SENSORY INPUT. THEREAFTER, AUTOTHROTTLE MOVEMENT MIGHT MATCH PLT INPUTS AND PLT WOULD NOT BE AWARE OF REENGAGEMENT. THIS IS, I THINK, ONE OF THE BAD ASPECTS OF THIS PARTICULAR AUTOFLT SYS. AUTOTHROTTLE ARM SWITCH HAS TO BE TURNED OFF TO PREVENT THIS FROM OCCURRING, BUT THEN WOULD NOT HAVE AUTOTHROTTLES IN CASE OF A MISSED APCH.

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.

Autothrottles advanced on touchdown resulting in an large transport bouncing back into the air momentarily. However, it did come back down prior to the first officer putting the throttles to flight idle.