Avoid the "I don't want to…but" construction. It always leads to asininities like this:
I don't want to trivialize the inhumane horrors that African slaves endured on slave ships destined for the Americas. But after a recent airplane trip, sitting tightly next to my neighbor in steerage seats, I feel the discomfort and pain endemic to the current air experience has certain curious similarities.
Because once you get past the extremely superficial similarity of an abstract packing problem, you're stuck calling sitting on well-cushioned seats while stewardesses bring you drinks "discomfort and pain" while also reminding your readers of what real pain was like. Perhaps Steven Heller was forced at gunpoint to make his flight, leaving his weeping children behind? Was he forced to sit in his own feces for a few weeks while the plane slowly hauled him thousands of miles from his home? If he asked for an extra bag of peanuts, would the angry stewardess throw him out through a porthole in mid-flight? Was he refused a round-trip ticket because he was expected to spend a lifetime at his destination in menial labor?
I think, perhaps, the exercise of comparing a slave ship to a modern jetliner ought to lead one to emphasize the differences, instead.