Shuttle flight rules get lost in translation

Inside the Flight Rules
In a real mission, we would have to detect anomalies, diagnose them, determine the proper response, inform the crew, and monitor the level of success of their response. And we would be expected to do this while beset by extremely tight time schedules, misled by false alarms and distracted by a prioritized list of other real problems calling for our attention.

Each rule was accompanied in the handbook by its rationale. Why had the rule been composed, and in what anticipated situations was it to be applied? What other factors might negate the desirability of the specified responses? What was the proper role of judgment and originality?

The Flight Rules that Cain was trying to explain, aimed at making a launch safe even with one or two failed tank sensors, are part of this genre. And these FRs really ought to work, because NASA engineers have reacted to a recent history of sensor problems by performing thousands of hours of new tests of the sensor’s performance, and by installing new circuits that provide hitherto-unavailable insights into the sensor’s functions and malfunctions.

The most important new diagnostic tool is a voltage monitor that can tell when a sensor has failed in the "wet" mode — falsely indicating that there's more fuel left than there really is. A small flag appears on display screens, labeling the "wet" indication as false. Previously, the sensor failure had to be deduced by comparing it to indications from other nearby sensors — and for that, the conflicting indicators had to vote the bad sensor "off the island," as if spaceflight were a "Survivor" episode.

This is no longer the case. The last two shuttle missions have used fuel tanks with these new tank sensors installed. In flight, the sensors performed perfectly, but during practice sessions back on Earth, trainers had simulated combinations of false and true readings from the entire set of sensors, in order to test the reactions of Mission Control.

Based on the way we have all been taught, I would confidently guess that Mission Control already has a pretty thorough "cheat sheet" drawn up and tested by fire, specifying the necessary responses to the entire gamut of possible combinations of failures.

Blessing the new rules
On Thursday, Cain explained that these reference charts had not yet been formally presented to the review process that would bless them as real Flight Rules (the capitalization was evident in Cain's enunciation). He had assigned an action to the group to whip them into shape in a day (or if needed, two or three days) and present them to his own special panel, the Mission Management Team. If the team at Mission Control could prove that their written rules resulted in the right answers under all conceivable conditions, they would be blessed by Cain’s team for use on this mission.

And that is what Cain had been trying to explain, using terms that sounded like they were everyday English but which, in arcane NASA practice, were much, much more. It is a rigorous application of those words in their Mission Control meanings, not any thermal tile or pressure hull or meteorite shield, that is the space shuttle’s main bulwark against disaster in flight.

I know it was that way for STS-1, because I had a small role in helping bring it about. And I have every confidence that Cain and his team can stay true to this tradition and establish the safety of launching Atlantis with fewer tank sensors than originally prescribed. And that’s because of, not in spite of, the non-standard meanings applied to standard English terms.

He and I do speak the same language, and we are connected by another bond. I was on duty for the very first moments of Columbia’s flight as it launched. Twenty-two years later, Cain was in charge of the Mission Control team that was on duty for the last moments of Columbia’s flight history, when conditions beyond human control destroyed it and its crew. He’s not going to forget that feeling of bafflement, helplessness and despair — and I’m confident he’ll make sure the new Flight Rules are built strong and safe.

James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer.

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