1. In the middle of a long flight, compare pilots' reaction times just before the nap to just after the nap. Result: After the nap, reaction times are 16% shorter.

2. Over the entirety of a long flight, test pilot reaction times initially, then at regular intervals until the end of the flight. Result: Without a nap, final reaction times are 34% slower than initial reaction times.

Yes, it's a little bit of a factoid soup, and citations would have been nice.

I think what they're saying is that:

"Pilots who nap for 30 minutes on a long haul flight improve their reaction time by an average 16% versus their initial reaction time. Pilots who don't take a nap experience a decline in their reaction times making their reaction to stimulus 34% [?] slower by the end of the flight."

People tend to say a persons "reaction time has decreased" when they mean the time taken to react has increased, reaction time is given as if it's a score rather than a time period.

If these are both "relative to baseline" and not "relative to one another," then yes (except for spelling and grammatical mistakes).

Of course, as stated, not taking a nap apparently gives a greater improvement, so presumably they didn't actually mean "decrease" and instead meant "increase."

What would the baseline be? Not told whether to nap or not? I imagine that's the same as non-napping, because most people don't nap.

Baseline would be the test that you performed prior to the flight.

Take 100 pilots. Test them all right before flying. Instruct 50 to nap during the flight. Instruct 50 not to. Compare each individual's response time after the flight to their response time before the flight. Aggregate by group. Perform a t-test (or another appropriate test) asking whether or not the difference (after minus before) is the same in both groups, or if one group performs better.

The editor should have taken a nap.