If federal regulators ground the Cessna 208 Caravan during even moderately icy conditions, the economic ramifications would be enormous on the overnight delivery of small parcels.

In the wake of recommendations last week by the National Transportation Safety Board (NTSB) to the Federal Aviation Administration (FAA), the Regional Air Cargo Carriers Association (RACCA) is meeting this week with Cessna officials to map out a strategy to keep the plane in the air.

RACCA members fly 350 single turbine engine, high-wing Caravans every night delivering packages for FedEx, UPS and DHL, said RACCA president Stan Bernstein. Some 70 percent of these planes are flown on routes subject to icing conditions in the winter. A grounding order would create chaos and confusion in the industry as carriers scramble to find planes that could replace the Cessna 208s. Those overnight packages just might not be delivered overnight, he noted.

The icing problems with the Cessna 208 are not new. In fact, earlier this month the FAA issued an airworthiness directive ordering operators to install a handhold on the plane so that the pilots can climb high enough to inspect the wings just before takeoff. RACCA had opposed the recommendations, claiming the handhold would not be effective and in some cases dangerous.

In its own filings, Cessna told the FAA that requiring installation of a t handle could mislead pilots into thinking that visual and tactile inspection of only the inboard leading edge area of the left wing upper surface is sufficient.

The directive also requires the installation of de-icing boots on the land gear struts and cargo pods.

The FAA estimates it will cost $11,500 to modify each plane. The director covers 752 Cessna Caravan and Grand Caravans now flying.

Over the last 15 years, the NTSB said at least nine accidents have involved icing. The FAA said at least one-third of these cases involved the build-up of ice while the plane was on the ground leading to accidents shortly after takeoff.

At the meeting in Wichita, Kan., Bernstein said RACCA is going to request that Cessna "conduct a thorough in-depth study of the icing issue in hopes they can define the problem. We would like them to come up with a fix for the aircraft. It is the manufacturer's responsibility to identify the problem and fix it."

The Wichita meeting is slated to include Cessna CEO Jack Pelton, its icing engineering team and customer support. Bernstein will be joined by senior officers of a number of carriers that fly the Cessna 208.

Despite the investigations over the years by both the NTSB and FAA, Bernstein said a cure for the problem has not been found. "One purpose of the meeting is for all parties to put our hands on the table and tell what we know."

While RACCA is looking for a long-term fix, it would like further guidance from Cessna as to how to best train pilots to detect ice buildup and to deal with it. "We want to get through the existing ice season and our recommendation to the members is to train, train and train."

In addition to stressing the need for continue training, Bernstein said the group has urged its members to adopt a management philosophy not to pressure pilots to fly in icy conditions. "When the pilot says 'no,' that means 'no,'" he said.

The NTSB made three urgent recommendations to FAA:

• Require all operators of Cessna 208 series airplanes to maintain a minimum operating airspeed of 120 knots during flight in icing conditions, even if a descent is required to do so.
• Prohibit all operators from flying in any icing conditions determined to be more than light icing.
• Require all operators to disengage the autopilot and fly the airplane manually when operating in icing conditions.

Bernstein said his group has not had a problem with the recommendations to increase the air speed or to turn off the autopilot.

NTSB has revisited the issue of the 208s and icing many times. The board has previously cited to FAA a string of 26 Cessna 208 accidents from 1987 to 2003, which killed 36 people. In a letter to FAA Administrator Marion Blakey explaining its rationale for the new recommendations, NTSB uses the particulars from two recent accidents from last fall. The first involved Morningstar Air Express cargo flight 208B on Oct. 6, which crashed and killed the pilot five minutes after takeoff from Winnipeg International Airport in an attempt to return to the airport. The second, which occurred on Nov. 19 and killed two pilots and six passengers, was on approach to Domodedovo International in Moscow.

Regarding the proper flight speed, NTSB indicates that for now it is settling on the figure of 120 knots because some type of minimal figure is needed now as guidance, until FAA issues its own standard. For the time being, it is important to err on the conservative side, the board indicated. Moreover, the board's previously recommended speed of 105 knots does not seem to leave a large enough margin of safety when pilots encounter icing during a flight. Icing can contribute to the speed lowering even further, which could contribute to a stall. The less the margin between operating speed and the safety minimum, the greater the risk.

The Cessna 208 crash near Moscow offers a prime example of this danger. "The airplane departed controlled flight only 3 knots slower than the published minimum operating icing airspeed of 105 knots and no stall warning was provided to the pilots," the board says. Thus, a truly safe speed would be considerably higher than the old minimum.

The 120-knot level also is the speed Cessna test pilots have used to safely exit from icing conditions. Indeed, the lowest speed the test planes reached in the process of exiting icing was 117 knots.

The crash near Winnipeg seems to inform the board's second recommendation, for Cessna 208 pilots to avoid all but the lightest icing conditions. "The board is also concerned that the airplane's failure to continue flight for more than 3 minutes in less-than-severe icing conditions calls into serious question the certification of the Cessna 208 for flight into known icing conditions. ... During certification flight tests and recent in-flight icing testing, Cessna 208 series airplanes experienced significant performance degradations while in icing conditions that were within the icing certification envelopes. During the March 2005 Cessna tests, a flight experienced a loss of airspeed to below 120 knots within 9 minutes after entering icing conditions that were characterized as "moderate."

The board notes that the pilot from Winnipeg did a preflight physical inspection of her craft's wings for ice and frost contamination. Then, only two minutes into the flight, she informed air traffic control that she was coming back in because of icing conditions.

But here, NTSB's summary leaves an important gap in one's understanding of the factors involved in the accident, Bernstein told Regional Aviation News. This is because there is no indication of whether the pilot actually found ice or frost on the wings before takeoff.

"We suspect that perhaps the aircraft took off with snow or ice on it. I have 25 years' flying experience in the Northeast with all kinds of freezing weather and I have never encountered conditions that could bring an aircraft down in three minutes," he said.

In concluding this line of discussion, NTSB says that "although the Cessna 208 can be operated safely in 'light' icing conditions, the airplane is at significant risk in icing conditions that are greater than light."

Such a statement makes one wonder why the board wouldn't recommend grounding the airplanes for any level of icing conditions.

Then again, these recommendations are only based on preliminary findings as a result of the board's ongoing assistance to Canadian and Russian authorities in investigating the two accidents, NTSB says.

The third recommendation to disengage the autopilot in icing conditions is because the autopilot can prevent the pilots from feeling what the current flying conditions are actually like. Moreover, if the decreases in altitude and speed are fairly gradual, and the series of control inputs the autopilot makes go unnoticed, it could be too late by the time pilots finally realize they should have resumed manual control.

Again, NTSB finds the crash near Moscow to be particularly instructive. "If the pilots involved in the Moscow accident had been flying the airplane manually (without the autopilot engaged), they likely would have noticed the increased control wheel force needed to maintain altitude, become aware of the airplane's altered performance characteristics, and increased their airspeed or otherwise altered their flight situation to avoid the loss of control."

Thus, the board "concludes that manually flying the Cessna 208 in icing conditions is necessary to enable pilots to sense the aerodynamic effects of icing and enhance their ability to retain control of the airplane."

>>The NTSB letter is at: http://www.ntsb.gov/recs/letters/2006/A06_01_03.pdf. Contact: Stan Bernstein, RACCA, (508) 778-7788.<<