[mund1011]

But if both aircraft are doing around 500 miles per hour, they can close that 11 miles in about 90 seconds.

++++++++++++

To make it easier two aircraft both doing 500mph closing is like one doing 1000mph.
1000mph = 16.66 mi/min
11 miles would be covered in 11/16.66 = 0.66min = 39.6 sec

[Psalm 73]

Thanks, man. I'm just awful at math.

(But I CAN balance a checkbook, something our politians can't seem to do).