Feds raised an alarm because of 135 crashes since 1993.
Federal crash investigations have made repeated calls for tougher rules and more research on flying in icing conditions because 135 planes have fallen out of the sky since 1993 because of ice.
And with 171 people dead, the National Transportation Safety Board is not happy with the slowness of the Federal Aviation Administration's response to pleas for action dating to 1996.
Today, smaller personal and corporate planes continue to be particularly vulnerable to ice. Investigators are considering ice as a cause in two recent fatal crashes in Colorado and Wyoming.
"Icing has always been a major concern," said Dan Bower, an NTSB engineer. "It's been on our most-wanted list [of aviation safety improvements] for years."
But the safety board can only recommend changes in the rules. It must wait for the FAA to conduct research and write new regulations.
In this case, the NTSB has been waiting for years for the FAA to act on four safety improvements concerning ice. The board wants more research, changes in aircraft design and testing, and clearer rules for pilots.
The FAA says it has been working hard and making progress, but that the research is complex and slow.
"It's not just an overnight issue," said the FAA's icing expert, Gene Hill. He could not predict a date for the issuance of new regulations.
Just last month, the NTSB raised its level of alarm about ice, with two more actions.
On Dec. 15, it issued a public warning, and requested FAA action, on the extraordinary number of icing accidents involving Cessna Caravans, a turboprop plane that can carry up to 14 people.
On Dec. 29, it issued an alert to all pilots, telling them to run their hands over the wings of their planes before takeoff to check for invisible ice. The alert warned that ice crystals as tiny as grains of salt scattered on a wing can be dangerous, cutting a plane's lift by one-third.
"We've seen a string of accidents, all related to icing," explained Bower. That includes ice that collects on the plane while it's on the ground, and ice that sticks to the aircraft in flight, he said.
Pilots of small and medium-size aircraft are repeatedly running into icing conditions that they or their aircraft can't seem to handle, he said.
The NTSB's sharp warnings started after ice caused two deadly accidents in 1992 and 1994: a US Airways Fokker F-28 crash on takeoff at New York's LaGuardia Airport that killed 27, and an American Eagle crash at Roselawn, Ind., that killed 68.
The airlines responded with stringent rules on when their planes must de-ice, and sometimes, de-ice again, NTSB and FAA officials said.
Since 1994, no large U.S. airliner has had a fatal crash due to ice.
All 85 deaths due to ice since then have been in small to medium-sized planes -- commuter airliners, general aviation planes and air taxis. The last category includes corporate and charter planes.
Large jets' advantage
Larger jets have several natural advantages, Bower added. For one, they fly in the icing danger zone -- below 20,000 feet -- only when taking off and landing. Smaller planes, on the other hand, may fly an entire trip in that zone, Bower said.
John Clark, the NTSB's head of aviation safety, said many pilots have seen their aircraft continue to operate while contaminated with ice -- even a ridge of ice extending forward off the leading edge of the wing -- and they seem to be learning the wrong lesson from this, he said.