NTSB recommends repairs for Boeing 737 rudders

Manufacturer says no flaws have been found

October 16, 1996
Web posted at: 8:45 p.m. EDT

WASHINGTON (CNN) -- In the wake of two unsolved plane crashes, U.S. safety officials Wednesday recommended a major overhaul of the tail rudder system in the Boeing 737, the world's most widely used jetliner.

The recommendations from the National Transportation Safety Board would require retrofitting existing planes and redesigning new ones to prevent possible loss of control from rudder failures. There are about 2,800 737s in service.

If adopted by the Federal Aviation Administration, the list of safety proposals would require Boeing to develop and install cockpit indicators that would provide details on rudder position and movements. (33 sec/1.4M QuickTime movie)

"The ball is clearly in their court," said Jim Hall, NTSB chairman, referring to the FAA. The FAA has 90 days to respond to the recommendations. If put in place, they could cost the airline industry tens of millions of dollars.

Boeing spokesman Tim Neale said the rudder system already has been redesigned for newer-model 737s now in production. The design change was needed because the aircraft is bigger than older models, not because of safety concerns, he said.

The NTSB's recommendations drew praise from the Airline Pilots Association. "These are pretty broad-reaching recommendations," said John Cox, a union spokesman and USAir pilot. "They're pretty much where they need to be."

Cause of crashes?

Government officials suspect that unsolved Boeing 737 crashes in Colorado Springs in 1991 and Pittsburgh in 1994 may have been caused by sudden, extreme movements of the rudder, an inadvertent maneuver known as a "hard over."

The USAir 737 crash September 8, 1994, near Pittsburgh killed all 132 people aboard. The March 3, 1991, United Airlines crash in Colorado killed 25.

But the FAA has been more circumspect than the NTSB in drawing conclusions about the crashes, saying it has found no reason to redesign the 737 rudder.

"There's never been a single flight-control problem documented in any place in the airplane," FAA Administrator David Hinson said. "There are circumstantial suggestions that there may be a rudder anomaly in the airplane. We'll very carefully evaluate their recommendation."

Boeing officials stress that, despite extensive investigations, no evidence of flaws in the 737 have been found that would have caused the two crashes.

The NTSB also recommended that Boeing 737 flight crews be better trained to deal with uncontrolled rolls, a practice some airlines have adopted.

New warning system for pilots

Another safety change is already under way, and it's not limited to the 737.

American Airlines said Wednesday it is spending $25 million to outfit its fleet with early-warning devices designed to prevent accidents like the December 1995 crash of a jetliner that slammed into a mountainside in Colombia.

Alaska Airlines and other airlines also plan to install the new Enhanced Ground Proximity Warning System, which uses Global Positioning Satellite signals with computerized maps to warn pilots they may be in trouble.

"It tells you 60 seconds before impact how close you are," American Airlines spokesman John Hotard said.

More improvements sought

Even with these enhancements, the skies may not be entirely safe for airline travelers in the long term. Hinson warned Wednesday that the number of airline crashes could increase, if major safety measures aren't pursued.

In the next 15 years, U.S. airlines will be carrying more than 1 billion passengers, double today's number, he said. Without changes, Hinson estimated there would be one major crash about every 10 days somewhere in the world.

Hinson cited a shift from ground-based to space-based air traffic control as a way to help controllers handle the increased air traffic. And he said the FAA is promoting a new Internet-based program that will let countries and airlines exchange safety information.

CNN Correspondent Carl Rochelle andReuters contributed to this report.

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