757 system question

[wmuflyguy]

A Mode C transponder uses static pressure to transmit a pressure altitude signal to the ground based equipment. The ground computer then corrects the data for the local altimeter setting and displays the data for the controller. Essentially, the transponder and altimeters were using the same erroneous pressure data.

I didn't think about that...good point.

 

[SLUF4]

I think it's good to review these incidents and think about what you would do in a situation like this. Like some others said, you would still have your groundspeed readout and RadAlt and I'm sure the 757 has an EGPWS display derived from GPS position. It seemed like they were under the impression that ATC radar would show their actual altitude and not what was given from the transponder. I feel really bad about this, but hopefully it's a reminder to do a thorough preflight and catch this stuff before it becomes a problem.

 

[jmreii]

as a pilot and a mechanic, whenever I take an aircraft out of maintenance that has been signed off to return to line service and before doing any preflight check I make sure the maintenance work was accomplished and complete. you would be surprise on what is forgot, opps pop goes the weasel. thank god for that valuable a&p experience.