AN ACR CAPT RPTS THAT THE AUTOFLT SYS ON THE MD88 HAS SOME 'ERRATIC AND POTENTIALLY HAZARDOUS' CHARACTERISTICS ASSOCIATED WITH THE VNAV AND AUTOTHROTTLE FUNCTIONS. THE RPTR ALSO COMPLAINS ABOUT A NAV PROGRAM IN THE FMC.

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THE VNAV CAPTURE FUNCTION OF AUTOPLT IS POTENTIALLY HAZARDOUS DURING CONDITIONS OF HIGH ACFT CLB PERFORMANCE (IE; LIGHT GROSS WT AND/OR LOW TEMP). IT IS NOT UNCOMMON FOR THE AUTOTHROTTLES TO PULL BACK PWR BELOW CLEAN SPD WHILE IN A TURN; AT 3000 FT MSL WITH LEVEL OFF AT 6000 FT MSL. EVEN CLBING AT 250 KTS PASSING THROUGH 10000 FT ENRTE TO 12000 FT IT IS NOT UNCOMMON FOR THE AUTOTHROTTLES TO PULL BACK PWR AND THEN JAM IT ON AGAIN TO ACCELERATE. THIS ERRATIC NATURE OF THE AUTOTHROTTLES REQUIRES THE PLT'S FULL ATTN; OR WILL BE MISSED WHILE PERFORMING OTHER FLT DUTIES AND RESULT IN AIRSPD FALLING BELOW SAFE LEVELS. THE INCLUSION OF THE 6000 FT INITIAL CLB ALT IN THE FMS FOR THE REDSS ONE DEP INHIBITS VNAV WHEN; WHILE ON VECTORS; WE ARE GIVEN CLRNC TO A HIGHER ALT. PLEASE REMOVE THIS RESTR FROM THE FMS DATA BANK FOR THE DEP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS RPTR SAID THAT SINCE HE HAS STARTED OPERATING THIS ACFT IN LINE OPS HE HAS DISCOVERED THAT IT DOES NOT ALWAYS SMOOTHLY AND CORRECTLY CAPTURE THE SELECTED ALT. THE MD88 AUTOTHROTTLES WILL START REDUCING THRUST WELL BEFORE THEY SHOULD AS THE ACFT APCHS ITS ALT HE SAID. ALSO HE COMPLAINED THAT IN SOME EXTREME CASES THE AUTOTHROTTLES WOULD ALLOW THE AIRSPD TO DECREASE TO A CRITICAL LEVEL IF HE WERE NOT WATCHFUL. HE ALSO COMPLAINED THAT IF THE LEVEL OFF ALT WAS AROUND 10000 FT OR SLIGHTLY ABOVE; THE AUTOTHROTTLES WOULD REDUCE AS THE ALT WAS CAPTURED AND THEN GO BACK TO FULL PWR AFTER LEVELING AT OR PASSING 10000 FT. LASTLY; THE RPTR COMPLAINED ABOUT A RECENT CHANGE IN THE SOFTWARE THAT WAS ANTICIPATING A NORMAL CLRNC THAT IS OFTEN GIVEN ON A DEP. HOWEVER; THE ALT RESTR IS NOT ALWAYS GIVEN YET; WITH THE SOFTWARE CHANGE; THE FMC ALWAYS TRIES TO MEET THE RESTR.