United Airlines still flying B787 through bad weather – is it safe?


United Airlines in the United States has not yet changed any routes because of icing, but they may be required to do so soon. Lufthansa flying the B 747-8 is still operating as scheduled.

Airlines that operate some Boeing 787s and 747s will be required to steer clear of some very large thunderstorms. This is according to a new rule by FAA.

Weather-related flight cancellations seldom happen because a plane can’t handle the prevailing conditions. Usually flight can’t operate because the airport shut itself down, or the airline decided to ground a large number of flights for operational reasons,

This may have changed according to a new emergency rule put in place by the US Federal Aviation Administration.

The airworthiness directive to be published Wednesday is meant to prevent ice build-up inside General Electric engines. The storms include those with clouds more than 60 miles across.

The FAA says it knows of nine instances where ice being sucked into an engine caused it to lose power. Two of those incidents caused engine damage on 747-8s.

eTN reported last week about Japan Airlines that had changed some routes already to avoid dangerous storms.

In the U.S.,the rule covers seven 787s flown by United Continental Holdings Inc., as well as some cargo-hauling 747-8s.

In the meantime a ferocious winter storm takes aim at the US East Coast later today, bringing a mix of rain, wind, snow, and ice, Thanksgiving air travelers may wonder if their holidays will be ruined.

Several hundred flights have already been canceled because of inclement weather in the Midwest, with Texas-based American Airlines and its regional carrier, American Eagle, hardest hit.

First the good news: Most commercial passenger planes are certified to fly in extreme conditions.

The Federal Aviation Administration (FAA) has a long list of flight requirements for commercial aircraft, which manufacturers generally exceed. Many of the rules are designed to ensure that your plane can operate in wind and snow.

However, just the anticipation of problems and long delays can spur airlines to cancel.

What are the factors for a decisions to cancel flights
In clear weather, winds are rarely a factor, and then only if they’re blowing across, not down, the runway. If you have a dry runway, you can take a crosswind of 25 knots in many commercial aircraft.

But in rain or snow—or any condition that slickens the runway—tolerance for a crosswind decreases. It becomes that much harder for a pilot to stay on the centerline of the runway without skidding, particularly when landing a large plane at 150 miles an hour. Brakes are the vital element, because a pilot can’t bring a plane to a stop using reverse thrust alone.

Each airline has FAA-approved formulas and tables it uses to determine the maximum crosswind. If a severe winter storm hits and causes ice on the runways, even a moderate crosswind could exceed the limits and make a takeoff or landing unsafe.

Light or moderate snow will not stop operations. A heavy snowfall, however, can cause cancellations.

Even planes that have been de-iced need to reach the runways, which often require heavy plowing.

And pilots could face difficulties generating flying speed in slush or standing water over a half-inch deep, or when there’s too much snow accumulation. In such conditions, the drag on the aircraft tires can be so great that a plane is unable to take off before the runway ends. Visibility can also be a factor.

Freezing rain
One thing planes don’t fly in is freezing rain. If an airport is hit with rain or drizzle when temperatures hover near the freezing point, airport authorities will consider shutting it down and most definitely the airlines will start canceling flights.

The reason? In such conditions, aircraft can gather ice faster than de-icing equipment can remove it, and ice can also wreak havoc on every other part of airport operations. An aircraft can lose traction in the ice, making it difficult to control. Critical equipment can freeze, and braking can become uncertain if not impossible.

New strategies
Airlines, airports, and the FAA do what they can to prevent weather from stranding passengers. But their strategies have changed in the last few years, particularly in light of the Department of Transportation’s 2009 rules on airport-tarmac delays, which fine airlines for keeping passengers on a parked plane for more than three hours.