Using .loc with a MultiIndex in pandas
If you are on version 0.14, you can simply pass a tuple to .loc as below:
df.loc[('at', [1,3,4]), 'Dwell']
Try the cross-section indexing:
In [68]: df.xs('at', level='QGram', drop_level=False).loc[[1,4]]
Out[68]:
Char Dwell Flight ND_Offset Offset
QGram
at 1 t 180 0 0.108363 5
4 a 20 180 0.000000 0