Extracting a section of data with conditions

I have two sets of data that correspond to one another: altitude and time. I have the time in datetime format and converted it to minutes (double). I need to extract the data from both between a specific time interval (start_t and end_t).

I think where I am running into trouble is my altitude is in a 837x1 table format.

[Image Analyst]

"I have two sets of data" <== yes but we don't because you forgot to attach them.

TUTORIAL: How to ask a question (on Answers) and get a fast answer

What if you just do

rowsToExtract = t.altitude > start_t & t.altitude < end_t;
altitude = t.altitude(rowsToExtract);

If that doesn't work, then blame it on me not having any data to work with.