Narrative:

The captain was flying this leg. We had just leveled at FL350. The captain was in a hurry to get back to base. This was not new for him; the whole sequence he had been pushing to fly at .79 mach. We were at a weight of 127;500 pounds. I checked the altitude/speed chart and saw that we were too heavy to be going this fast. The chart called for a weight of 125;000 pounds or less to go this fast. So I tried to tell the captain in a quiet manner that we were too heavy. He let me know in no uncertain terms that he was not interested in my input. Not long after this comment; we entered what I would call heavy high speed buffet. The captain slowed the jet for a few minutes; then we went right back to .79 mach. I was not as forceful with this captain about his speed as I should have been; because we had an FAA observer in the jumpseat. He was a general aviation expert; so I do not know how familiar he is with the md-80. I did not want to make a big deal about it in front of this man; so I decided to watch the airplane very carefully so as to keep it from going too fast. Looking back; this was a poor decision. I should have let it be known at that point that we were going to slow period. This will not happen again. At the gate; I waited for everyone to leave so that it was just the two of us. I asked him why he was going so fast. His response was; 'they changed the chart a few years ago and not the wing. They don't know what they are doing.' I decided that it was not worth any further conversation. He was not going to change his mind.

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Original NASA ASRS Text

Title: An MD80 First Officer reported that his Captain repeatedly refused to slow the aircraft below the high speed buffet mach number for the aircraft's weight at FL350. High speed mach buffet occurred.

Narrative: The Captain was flying this leg. We had just leveled at FL350. The Captain was in a hurry to get back to base. This was not new for him; the whole sequence he had been pushing to fly at .79 mach. We were at a weight of 127;500 LBS. I checked the altitude/speed chart and saw that we were too heavy to be going this fast. The chart called for a weight of 125;000 LBS or less to go this fast. So I tried to tell the Captain in a quiet manner that we were too heavy. He let me know in no uncertain terms that he was not interested in my input. Not long after this comment; we entered what I would call heavy high speed buffet. The Captain slowed the jet for a few minutes; then we went right back to .79 mach. I was not as forceful with this Captain about his speed as I should have been; because we had an FAA Observer in the jumpseat. He was a general aviation expert; so I do not know how familiar he is with the MD-80. I did not want to make a big deal about it in front of this man; so I decided to watch the airplane very carefully so as to keep it from going too fast. Looking back; this was a poor decision. I should have let it be known at that point that we were going to slow period. This will not happen again. At the gate; I waited for everyone to leave so that it was just the two of us. I asked him why he was going so fast. His response was; 'they changed the chart a few years ago and not the wing. They don't know what they are doing.' I decided that it was not worth any further conversation. He was not going to change his mind.

Data retrieved from NASA's ASRS site as of April 2012 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.