Narrative:

I was cleared for takeoff following medium large transport Y aircraft before it had rotated. I delayed takeoff until I was assured that medium large transport Y would be turned away as my clearance was to maintain runway heading. I was handed off to departure in time to hear the controller give medium large transport Y a 280 degree heading. I was given a 260 degree heading and I executed the turn quickly so as to not overrun the traffic which was climbing slower. I was given and accepted a clearance to maintain visual sep with medium large transport Y during the initial climb out. The medium large transport Y was next given a left turn to 120 degrees and began to comply with the clearance. In order to maintain visual with medium large transport Y I had to reduce power and level off while the controller issued me a left turn to 110 degrees. I executed the turn but remained level as I had lost visual with the climbing medium large transport Y and I was no longer complying with the climb clearance of the SID. The aircraft I was flying is an advanced model of medium large transport X and speed control under 250 KTS became a problem west/O abrupt power changes that overrode the autothrottle operation. I was hand flying at the time and the autothrottles were engaged in the climb mode which is the SOP. However, I quickly realized that the autothrottles do not respond fast enough and therefore I disconnected them so as to reduce to 250 KTS below 10000'. I expressed my displeasure to the controller with the departure procedures and maintained level until I was assured adequate sep. I was cleared to climb to 17000' and informed that medium large transport Y was at my 6 O'clock and 10 mi. Had I not leveled off and followed the controller's clearance I believe that sep would have become lessened to the point where we would have had to file a near miss report. Nighttime judgement of distance is difficult, but I judged my distance to be 2 mi from the medium large transport Y, 8 O'clock when he was issued the left turn to 120 degrees. The speed seemed faster and my climb rate was faster. While on diverging courses it was no problem until the medium large transport was turned into me.

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Original NASA ASRS Text

Title: ACR MLG EXCEEDED 250 KTS BELOW 10000' AND THUS HAD DIFFICULTY MAINTAINING VISUAL SEPARATION WITH OTHER DEP TRAFFIC.

Narrative: I WAS CLRED FOR TKOF FOLLOWING MLG Y ACFT BEFORE IT HAD ROTATED. I DELAYED TKOF UNTIL I WAS ASSURED THAT MLG Y WOULD BE TURNED AWAY AS MY CLRNC WAS TO MAINTAIN RWY HDG. I WAS HANDED OFF TO DEP IN TIME TO HEAR THE CTLR GIVE MLG Y A 280 DEG HDG. I WAS GIVEN A 260 DEG HDG AND I EXECUTED THE TURN QUICKLY SO AS TO NOT OVERRUN THE TFC WHICH WAS CLBING SLOWER. I WAS GIVEN AND ACCEPTED A CLRNC TO MAINTAIN VISUAL SEP WITH MLG Y DURING THE INITIAL CLBOUT. THE MLG Y WAS NEXT GIVEN A LEFT TURN TO 120 DEGS AND BEGAN TO COMPLY WITH THE CLRNC. IN ORDER TO MAINTAIN VISUAL WITH MLG Y I HAD TO REDUCE PWR AND LEVEL OFF WHILE THE CTLR ISSUED ME A LEFT TURN TO 110 DEGS. I EXECUTED THE TURN BUT REMAINED LEVEL AS I HAD LOST VISUAL WITH THE CLBING MLG Y AND I WAS NO LONGER COMPLYING WITH THE CLB CLRNC OF THE SID. THE ACFT I WAS FLYING IS AN ADVANCED MODEL OF MLG X AND SPD CTL UNDER 250 KTS BECAME A PROB W/O ABRUPT PWR CHANGES THAT OVERRODE THE AUTOTHROTTLE OPERATION. I WAS HAND FLYING AT THE TIME AND THE AUTOTHROTTLES WERE ENGAGED IN THE CLB MODE WHICH IS THE SOP. HOWEVER, I QUICKLY REALIZED THAT THE AUTOTHROTTLES DO NOT RESPOND FAST ENOUGH AND THEREFORE I DISCONNECTED THEM SO AS TO REDUCE TO 250 KTS BELOW 10000'. I EXPRESSED MY DISPLEASURE TO THE CTLR WITH THE DEP PROCS AND MAINTAINED LEVEL UNTIL I WAS ASSURED ADEQUATE SEP. I WAS CLRED TO CLB TO 17000' AND INFORMED THAT MLG Y WAS AT MY 6 O'CLOCK AND 10 MI. HAD I NOT LEVELED OFF AND FOLLOWED THE CTLR'S CLRNC I BELIEVE THAT SEP WOULD HAVE BECOME LESSENED TO THE POINT WHERE WE WOULD HAVE HAD TO FILE A NEAR MISS RPT. NIGHTTIME JUDGEMENT OF DISTANCE IS DIFFICULT, BUT I JUDGED MY DISTANCE TO BE 2 MI FROM THE MLG Y, 8 O'CLOCK WHEN HE WAS ISSUED THE LEFT TURN TO 120 DEGS. THE SPD SEEMED FASTER AND MY CLB RATE WAS FASTER. WHILE ON DIVERGING COURSES IT WAS NO PROB UNTIL THE MLG WAS TURNED INTO ME.

Data retrieved from NASA's ASRS site as of August 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.