By Kim Smiley
The Mars Climate Orbiter (MCO) was launched atop a Delta II launch vehicle on December 11, 1998. Nine and a half months after launch, the MCO was scheduled to begin the process of establishing an orbit around Mars. The plan was to use a technique called aerobraking to reduce the MCO velocity and slowly move the MCO from a 14 hour orbit to a 2 hour orbit. On September 23, the $125 million dollar MCO was lost during the attempt to establish orbit around Mars. Investigation into the accident revealed that the orbiter had entered the Martian atmosphere traveling too quickly with too low a trajectory. The heat produced by friction from hitting the thicker atmosphere present at the lower trajectory at high velocity destroyed the orbiter. The loss of the MCO cost NASA more than the $125 million dollars spent building the MCO. In addition, NASA lost a substantial amount of time, lost all potentially gathered data, and lost some of the public support for the NASA program.
NASA investigation revealed many causes of the loss of the orbiter. One of the most obvious causes is a unit error in the software used to help predict the velocity of the MCO, which in turn is used to predict the trajectory the MCO would enter Martian atmosphere. A little background is needed to understand how an error in the software causes errors in the predicted velocity. Software called “Small Forces” is used to predict how the MCO’s velocity changed after a angular momentum desturation maneuver. A angular momentum desturation maneuver is performed when one of the momentum wheels used to help the orbiter maintain orientation in space starts spinning too quickly. During an angular momentum desturation maneuver, a wheel is deliberately slowed down (which would normally turn the spacecraft) while at the same time a jet is fired to counteract this force and keep the orientation relatively constant. This whole process affects the speed the spacecraft is traveling and affects the trajectory of entry in the Mars atmosphere. The error in Small Forces was simple one. The results were in pound force and the program that predicted velocity expected them to be in Newtons.
The attached PDF file contains an intermediate level root cause analysis of the loss of the MCO. It was built using facts from media reports and the NASA investigation reports. The map can be expanded using all the known data to create a detailed Cause Map.
Learn more about the Mars Climate Orbiter.
By Kim Smiley
American Airlines resumed a normal flight schedule Saturday afternoon, ending a period of widespread flight cancellations. Between April 8 and 12, 3,300 flights were canceled when all MD-80 jetliners in the American Airlines fleet were grounded. More than a quarter of a million passengers were affected by the widespread flight cancellations. As discussed in a previous blog, these drastic measures were taken when a large percentage of inspected MD-80s failed to meet FAA regulations on wiring from the airframe to a pump in the wheel well. The wiring can be a fire hazard and affect power distribution. An intermediate level Cause Map showing the causes of the cancellations can be seen in the previous blog posted on April 10.
The cancellations may be over, but the effects will continue to linger. The cost to the American Airline is estimated to be in the tens of millions of dollars. In addition to lost revenue, American Airlines gave many inconvenienced passengers $500 travel vouchers and paid to put stranded travelers in hotels. It is also difficult to put a financial cost on the huge amount of negative publicity that the airline has received as a result of these cancellations, but it is guaranteed to affect their business. In addition to the financial burden of these cancellations, the entire airline industry is faced with raising fuel costs and this is going to put even more pressure on American Airlines. Already, American Airlines announced on Friday (ironically on a day when nearly 600 flights were canceled) that it will be raising prices by as much as $30 a round trip tickets to help compensate for high fuel costs. These dual blows to the bottom line are going to affect the health of the American Airline company for the foreseeable future.
It is also likely that many other airlines will be similarlly affected. Doing a root cause analysis, it is clear that one of the causes of these cancellations is a new focus by the FAA on “zero tolerance” for any deviations from their detailed regulations. As airlines struggle to understand the new inspection criteria, it is likely that other airlines will face cancellations. The airline industry as a whole is facing some high hurdles in the upcoming months. Four discount carriers have already declared bankruptcy in the last month and it is likely others will follow suit. Even the established, traditional carriers are seeking changes to stay competitive. For example, rumors are circulating about a possible Northwest and Delta merger. This is going to be a turbulent time for Airlines and passengers.
By Kim Smiley
Starting April 8, 2008, American Airlines grounded nearly half of its fleet when it pulled all 300 McDonell Douglas jets (MD-80s) from service. At least 2,400 flights were canceled. It is estimated that 100 passengers would have been on each of the canceled flights, bringing the total of affected passengers to nearly a quarter of a million people. The MD-80s were grounded because 15 of 19 inspected aircraft failed FAA inspection this week. The issue is with the installation of wiring connecting the airframe to a hydraulic pump in the wheel well. The regulations are written to prevent rubbing and chafing of the wiring, which can lead to exposed wiring. Exposed wiring is a concern because it can to power issues and shorts, and it is a potential fire hazard.
The most alarming part of the story is that American Airlines grounded these same planes for the exact same issue on March 26 and 27. Over 350 flights were canceled while the planes were inspected and repaired if necessary to compile with the FAA wiring regulations. All planes were back in service on March 28 after American Airlines asserted they satisfied the regulation. Little information is available on what went wrong two weeks ago. There are a number of questions that would need to be answered to perform a thorough investigation. Are the FAA regulations confusing? Do the AA mechanics need additional training? Did the airline fail to internally check the wiring prior to putting the planes back into service? If an inspection did occur, did the inspectors understand what they were looking for? It may not be clear exactly what went wrong, but it is clear that something failed in the system to cause this second round of cancellations.
The attached PDF file contains an intermediate level root cause analysis of the cancellation of American Airline flights on April 8-9. It was built using the facts that were available in media report. There are many details still missing, that could be added as more details are known.
By Kim Smiley
Just before 11 am on January 25, 2008, a fire started on the roof of the 32 story Monte Carlo Hotel in Las Vegas. The fire spread quickly along the outside of the building, fueled by the highly flammable foam like material, Exterior Insulation Finishing System (EIFS), used to construct the hotel façade. A spark from a hand held cutting torch being used on the roof of the hotel hit the EIFS and started the fire. 6,000 guests and workers were evacuated from the hotel. The hotel remained closed until February 15. Considering both the damage to the hotel and lost business, the total cost of the fire is approximately $100 million dollars. Luckily, no major injuries resulted from the fire.
A thorough root cause analysis built as a Cause Map can capture all of the causes in a simple, intuitive format that fits on one page. The Cause Map shows that the fire started because a spark from a hand held torch hit a flammable material. The Cause Map can also be used to identify possible solutions that would prevent another fire. In this case, two areas that would merit farther investigation would be the use of highly flammable material on buildings and the lack of protective measures taken to protect the EIFS from the sparks. For example, there were no mats in place to protect the EIFS from being hit by sparks. From the information available, it isn’t clear why no protective measures were taken to protect the EIFS, but it is known that the contractor failed to obtain the correct permit (which involves getting information on appropriate safety procedures). It is reported in an Associated Press article on the fire that Las Vegas city officials are currently evaluating whether restrictions should be placed on the use of EIFS.
The attached PDF file contains an intermediate level root cause analysis of the hotel fire. It was built using the facts that were available in media reports on the fire. As more details are known, the Cause Map can be expanded.