"It appears that some pilots believe that if they cannot see ice or frost on the wing from a distance, or maybe through a cockpit or cabin window, it must not be there, of if it is there and they cannot see it under those circumstances, then the accumulation must be too minute to be of any consequence," declares an Alert to Pilots issued Dec. 29, 2004, by the National Transportation Safety Board (NTSB).

The four-page advisory marks a significant development in NTSB activity. It is the first time the safety board has gone directly to the operating community with safety-related information. The alert reflects growing NTSB impatience with the Federal Aviation Administration's (FAA) slow pace of needed safety improvements. At a breakfast meeting with reporters last week, NTSB Chairman Ellen Engleman Conners said, "The FAA was not listening. You'll see more advocacy from the board."

Engleman Conners alluded to NTSB frustration, catalyzed by three recent accidents in icing conditions while FAA-directed research, studies and whatnot continue at a stately pace in the decade since the icing-related ATR-72 crash at Roselawn, Ill. (see ASW, Nov. 8, 2004). Needed action on airframe icing has been on the NTSB's "Most Wanted" list of safety improvements since 1997, and the NTSB characterized the response as "unacceptable" just 19 days before the Nov. 28, 2004, crash on takeoff of a Challenger 601 at Montrose, Calif. (see ASW, Dec. 6, 2004). On Dec. 15, 2004, the NTSB recommended that the FAA require pilots of Cessna 208 series airplanes to conduct both visual and tactile inspections of their airplanes for any ice contamination prior to takeoff (see ASW, Jan. 3).

Two weeks later, the board issued its pilot alert.

"While the FAA is being prudent in its studies, we'd like pilots to be prudent in their decision-making," Engleman Conners said. Hence, the unprecedented alert. It marks a dramatic shift in the NTSB's approach to time-sensitive safety issues. Following the Nov. 12, 2001, crash of American Airlines [AMR] Flight 587, the NTSB urged the FAA to caution pilots about excessive use of the rudder and to avoid rudder reversals, which were suspected to have led to tailfin separation in that accident (see ASW, Feb. 18, 2002). In response, the FAA and manufacturers published a wealth of advisory material urging pilots to be prudent in their use of the rudder.

In this case, the NTSB has sidestepped the FAA, going directly to the pilot community. The alert warns pilots that ice contamination on the upper surface compromises the wing's lift-generating function:

• "Research results have shown that fine particles of frost or ice, the size of a grain of table salt and distributed as sparsely as one per square centimeter over an airplane wing's upper surface can destroy enough lift to prevent that aircraft from taking off."
• "It is also possible that many pilots believe ... They can simply 'power through' any performance degradation that might result from almost imperceptible amounts of upper wing surface ice accumulation. However, engine power will not prevent a stall and loss of control at lift off, where the highest angles of attack are normally achieved."
• "Further, small patches of almost imperceptible ice or frost can result in localized, asymmetrical stalls on the wing, which can result in roll control problems during lift off."
• "It may be difficult for a pilot to see ice on the upper wing surface from the ground or through the cockpit or other windows. Further, frost, snow, and rime ice can be very difficult to detect on a white upper wing surface and clear ice can be difficult to detect on an upper wing surface of any color. However, it is critically important to ensure, by any means necessary, that the upper wing surface is clear of contamination before takeoff [by] visual and tactile inspections."

To all of these precautionary procedures, a plug for thermal de-icing with lasers bears mention once again (see ASW, Nov. 10, 2003). When one:

• Considers the cost of de-icing with fluids (on top of which one can stack all the environmental concerns for getting rid of "spent" de-icing fluid and the fumes in the cockpit plus APU problems resulting from de-icing fluid getting where it's not supposed to go), and
• Hears about these pilots taking a chance, and
• Looks at the hold-over rules (for starting the process all over again), plus
• Recalls all the accidents caused by failure to de-ice, and
• Notes all the ground accidents caused by de-icing rigs striking aircraft, then ...

Thermal laser de-icing on the ground (and thermal laser anti-icing airborne) might prove to be a real blessing and a big boon to safety.