A Safety Argument Against Stupid Software

Everyone is already familiar with the peculiar incident last week where we saw a Delta/Northwest Airlines A320 on a flight plan from San Diego to Minneapolis remain out of contact with ATC for over an hour, overfly its destination by 150 miles and then turn around and land over an hour late, with both pilots claiming they weren't sleeping, had merely been so thoroughly engrossed in discussion of company policy that they missed the radio calls and lost track of time.

This FlightAware track, which I can't see because I'm on stupid, stupid hotel internet, should show its path and this terse NTSB press release gives the facts.

I'm not sure whether your pilots missing their exit because of a "heated discussion" is preferable to their falling asleep. Falling asleep can be called an involuntary physical reaction to being sleep deprived, rather than deliberate neglect of responsibility. I guess the argument is that if you're awake in a discussion you're more likely to notice and correct a abnormal condition, but the facts of the case dispute that argument, seeing as they failed to answer multiple ATC calls, SELCAL signals or notice that they had reached the point at which they should have been descending.

I wasn't there, so I instead present the top ten explanations for the tardiness of flight 188:

• 10. intense discussion of company policy
• 9. sleeping
• 8. playing a game of chicken on when to start the descent
• 7. waiting for the movie to end
• 6. hoping for some talk show appearances to jumpstart new careers as "celebrities"
• 5. flying over the captain's girfriend's house to check for a strange car in the driveway
• 4. trying to confirm rumours of a "Tetris mode" on the FMS
• 3. joining the six-mile-high club
• 2. abducted by aliens for two weeks, then replaced in the cockpit with no memory of the event, and only an hour later in Earth time
• 1. just wanted to supplement their paycheques with a couple of hours extra pay

The NTSB, as mentioned in the press release, has pulled the cockpit voice recorder, but the variety in that plane only records the previous 30 minutes of conversation. The pilots would have known that, and whatever happened they used the 150 miles of backtracking to get their story straight. I'm guessing by passing notes, or typing on someone's PDA, while the CVR recorded only normal cockpit sounds.

There's a malfunction that occurs sometimes on those old cockpit voice recorders. I know about it because has come into play in at least one accident investigation. While the tape loops around every 30 minutes, sometimes the old track isn't erased, and you get an audio equivalent of the double exposure. I have no idea how rare this is.

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Update: I can't find a link to this on the NTSB site, but here's the latest on the investigation:

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NTSB ADVISORY

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National Transportation Safety Board
Washington, DC 20594

October 26, 2009

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NTSB ISSUES UPDATE ON ITS INVESTIGATION OF FLIGHT 188 THAT OVERFLEW INTENDED MINNEAPOLIS AIRPORT

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In its continuing investigation of an Airbus A320 that overflew the Minneapolis-St Paul International/Wold- Chamberlain Airport (MSP), the National Transportation Safety Board has developed the following factual information: On Wednesday, October 21, 2009, at 5:56 pm mountain daylight time, an Airbus A320, operating as Northwest Airlines (NWA) flight 188, became a NORDO (no radio communications) flight at 37,000 feet. The flight was operating as a Part 121 flight from San Diego International Airport, San Diego, California (SAN) to MSP with 144 passengers, 2 pilots and 3 flight attendants.

Both pilots were interviewed separately by NTSB investigators yesterday in Minnesota. The following is an overview of the interviews:

• The first officer and the captain were interviewed for over 5 hours combined.
• The Captain, 53 years old, was hired in 1985. His total flight time is about 20,000 hours, about 10,000 hours of A-320 time of which about 7,000 was as pilot in command.
• The First Officer, 54 years old, was hired in 1997. His total flight time is about 11,000 hours, and has about 5,000 hours on the A-320.
• Both pilots said they had never had an accident, incident or violation.
• Neither pilot reported any ongoing medical conditions.
• Both pilots stated that they were not fatigued. They were both commuters, but they had a 19-hour layover in San Diego just prior to the incident flight. Both said they did not fall asleep or doze during the flight.
• Both said there was no heated argument.
• Both stated there was a distraction in the cockpit.

The pilots said there was a concentrated period of discussion where they did not monitor the airplane or calls from ATC even though both stated they heard conversation on the radio. Also, neither pilot noticed messages that were sent by company dispatchers. They were discussing the new monthly crew flight scheduling system that was now in place as a result of the merger. The discussion began at cruise altitude.

• Both said they lost track of time.
• Each pilot accessed and used his personal laptop computer while they discussed the airline crew flight scheduling procedure. The first officer, who was more familiar with the procedure was providing instruction to the captain. The use of personal computers on the flight deck is prohibited by company policy.
• Neither pilot was aware of the airplane's position until a flight attendant called about 5 minutes before they were scheduled to land and asked what was their estimated time of arrival (ETA). The captain said, at that point, he looked at his primary flight display for an ETA and realized that they had passed MSP. They made contact with ATC and were given vectors back to MSP.
• At cruise altitude - the pilots stated they were using cockpit speakers to listen to radio communications, not their headsets.
• When asked by ATC what the problem was, they replied "just cockpit distraction" and "dealing with company issues".
• Both pilots said there are no procedures for the flight attendants to check on the pilots during flight.

The Safety Board is interviewing the flight attendants and other company personnel today. Air traffic control communications have been obtained and are being analyzed. Preliminary data from the cockpit voice recorder (CVR) revealed the following:

• The CVR recording was 1/2 hour in length.
• The cockpit area microphone channel was not working during this recording. However, the crew's headset microphones recorded their conversations.
• The CVR recording began during final approach, and continued while the aircraft was at the gate.
• During the hours immediately following the incident flight, routine aircraft maintenance provided power to the CVR for a few minutes on several occasions, likely recording over several minutes of the flight.

The FDR captured the entire flight which contained several hundred aircraft parameters including the portion of flight where there was no radio communication from the flight crew. Investigators are examining the recorded parameters to see if any information regarding crew activity during the portion of flight where radio contact was lost can be obtained.

The Safety Board's investigation continues.

It sounds like I missed possibility #11: Computer software lessons in my list. And I hope the final report answers my greatest outstanding question on the matter: were they Macs or PCs?