After the plane landed (safely) there was a great deal of speculation that the pilots had fallen asleep. The actual explanation is less interesting. They were distracted by their laptops! According to report just issued by the FAA, the two pilots had their laptops out and were trying to figure out a flight scheduling system that was new to the captain.
Mr. Cheney, 53, with 24 spotless years with the airline, and Mr. Cole, 54, who started flying at 14 and also had a spotless record, were going over Mr. Cheney’s schedule. Applying for a schedule under new computer procedures at Delta, the airline that acquired Northwest earlier in the year, Mr. Cheney had received a schedule that he did not like and that would have him at work for three additional days a month, the two men told investigators. They had both pulled out their laptops as Mr. Cole tried to help Mr. Cheney understand how to work the new system.
The documents contained a summary of interviews with Mr. Cheney and Mr. Cole, and added some fresh details. For example, the crew members reported hearing “radio chatter” but no calls for them; the reason, they told investigators, was that Mr. Cole had apparently tuned the radio to the frequency for an air traffic control center in Winnipeg, Manitoba. After the flight, investigators discovered that when a flight attendant used an on-board telephone to ask the pilots when the plane would be landing, the crew first spoke to the Winnipeg controllers. (source)
No recommendations for change, yet, but that will probably come. The New York Times, for instance, speculates that perhaps the Airbus A320 will a chime or other noise when text messages are sent to the aircraft.
Sadly, there have been a number of accidents caused by pilots being distracted. Most famously, perhaps, in the tragic crash of Easter Air Flight 401 in the Florida Everglades. Both pilots and the flight engineer were trying to troubleshoot a burned out landing gear indicator light and didn't notice that they had switched the autopilot mode to maintain pitch rather than maintain altitude. Then the pilot accidentally pushed the yoke forward and didn't notice the slow descent this caused.
The last words of the crew were these:
(1st Officer) Stockstill: We did something to the altitude.
(Captain) Loft: What?
Stockstill We're still at 2,000 feet, right?
Loft: Hey — what's happening here?
These days, pilots are trained in what's known as Cockpit Resource Management. The gist of which is: "One guy flies while the other guy fixes."
(As an interesting aside, there were numerous reported ghost sightings in planes that received salvaged parts from EA 401.)