>>15 miles in a jet is the blink of an eye...<<
Well, actually it’s a bit less than 3 minutes. Also, you don’t wait ‘till you’re over the airport to start down. They were probably at 20,000 or less. That means that they’d start down at 40-60 miles from the field.
OK, now that I’m retired, here’s the real story: Did we ever sleep in the cockpit? Yes; here’s how it worked:
Say I’m getting heavy eyelids enroute (at cruise altitude). The sensible approach: I turn to the other pilot and say “Bob, are you feeling OK?” If he says “yes”, I say “can you take (i.e. talk on) the radios and fly for a few minutes? I’m going to lean my chair back.”
If he says “I’m feeling really wiped out”, you figure out who is the worse off; that person gets up, stretches his legs, goes to the john, washes his face, gets a coffee, etc. The other person toughs it out ‘till he gets back, then does the same.
The dumb approach: You try to fake it. Result - BOTH of you end up in Zombie land. I suspect that’s what happened here.
How long a snooze? In most cases, it took about 5 minutes and you were feeling fine again. In 30 years of airline flying (+ 4 years flying the big jets in the Air Force) it never took over 20-25 minutes of shuteye.
What gets you that tired? Long days? Nope. Scheduling. One day you start work at 5:00 AM, the next at 10:00 PM. There’s no way you can prepare your body for that extreme kind of biorhythm change.
My experience level: Type rated in B-707/720/737/757/767 with about 16,000 hours total flight time. Lotsa east-west globe circling as a DC-8 copilot.