Why do planes crash? Michael Toppa University of Pennsylvania Perelman School of Medicine Information Services July 28, 2011
Why do planes crash? Itsnot like the movies “The typical commercial jetliner is about as dependable as a toaster” Poor weather Tired pilots, awake more than 12 hours Behind schedule, so the crew is hurrying Pilot and co-pilot have not flown together before
The cumulative effect of smallerrors Crashes are the result, on average, of 7 consecutive human errors No single error is disastrous, but the cumulative effect is Studies show this is typical in disasters involving any complex system The 3 Mile Island nuclear disaster was the result of 5 minor, consecutive human errors I believe there are lessons here for our work as well Poor communication among the crew is a key factor
Mitigated speech Whenwe try to downplay or sugarcoat the meaning of what we say, because were Being polite Feeling embarrassed Being deferential to authority
Hypothetical scenario In a research study, pilots were presented with a hypothetical scenario, and asked how they would handle it They are in the role of co-pilot, they see bad weather ahead, and they want to make sure they dont fly into it. What do they say to the pilot?
6 possible responses1.Command: “turn 30 degrees to the right”2.Crew obligation statement: “I think we need to deviate right about now”3.Crew suggestion: “Lets go around the weather”4.Query: “Which direction would you like to deviate?”5.Preference: “I think it would be wise to turn left or right”6.Hint: “That return at 25 miles looks mean”
The responses Pilots with the rank of Captain overwhelmingly chose the “command” option Pilots with the rank of First Officer overwhelmingly chose the “hint” option This may seem alarming, because it is! “A hint is the hardest kind of request to decode and the easiest to refuse”
1982 Air Florida Crash The plane had a problem with wing ice before takeoff First officer: “Look how the ice is just hanging on his, ah, back, back there, see that?” First officer, again: “Boy, this is a, this is a losing battle here on trying to de-ice those things, it gives you a false sense of security, thats all it does.” The captain doesnt get the hint, and the plane plunges into the Potomac river a few minutes after take off.
Avianca Flight 052 The captain is exhausted Planes are normally very low on fuel when landing, but this flight is literally running on empty First officer to ATC: “Climb and maintain three thousand and, ah, were running out of fuel, sir” ATC responds with a command to continue circling, and asks for confirmation its ok. First officer to ATC: “I guess so. Thank you very much”A flight attendant enters the cockpit, and the engineer makes a throat-cutting gesture to her Two engines flame out and the plane crashes
KAL Flight 801 The captain is experienced, but exhausted, its night, and the weather is terrible The captain has flown to this airport several times before He decides on a visual approach, using the airports beacon to navigate Hes forgotten the beacon is on a mountain near the airport
KAL Flight 801, continued First officer: “Dont you think it rains more? In this area, here?” Engineer: “Captain, the weather radar has helped a lot” They are trying to tell the captain they shouldnt be making a visual approach Korean language and culture makes it more difficult to speak directly The plane crashes into the mountain
Dealing with mitigated speech Crashes are more common with the Captain in the flying seat “Planes are safer when the least experienced pilot is flying, because it means the second [more experienced] pilot isnt going to be afraid to speak up” For 15 years the airline industry has trained flight crews on reducing mitigated speech Standardized procedures for escalating communication If necessary, temporarily relieving the Captain of duty KAL switched to English-only in the cockpit
Example from The Clean Coder Mike: “Paula, I need the login page done by tomorrow” Paula: “Oh, sorry Mike, but its going to take more time than that” Mike: “When do you think you can have it done?” Paula: “How about two weeks from now?” Mike: (scribbles something in his daytimer) “OK, thanks”
Passive Aggressiveness,Saying No By not speaking more firmly, Paula is inviting doubt about her estimate What if Mike went to his boss and blamed Paula for the project being late? Thats “morally reprehensible” passive aggressiveness Saying no can be the first step in a negotiation towards the best possible outcome