Smaller commercial aircraft will be required to meet more stringent standards for operating in icing conditions under a new Federal Aviation Administration rule released today.

The rule, made public by the US Office of the Federal Register, will require aircraft with a gross takeoff weight of less than 27,216kg (60,000lb) be able to operate safely in freezing drizzle and freezing rain – weather that the FAA calls “supercooled large drop” conditions.

The rule also requires aircraft to have systems that can detect freezing drizzle and freezing rain.

In addition, the FAA will require that aircraft engines and some components, such as angle of attack and airspeed indicators, be able to operate properly in freezing rain and other icing conditions.

The rule will be published in the federal register on 4 October and will take effect 60 days later.

The changes, which apply to the government’s “part 25” airworthiness standards for transport aircraft, are rooted in the icing-induced crash of an ATR 72 turboprop in Roselawn, Indiana, almost exactly 20 years ago.

On 31 October 1994, that aircraft, operated by Simmons Airlines under the American Eagle brand, was in a holding pattern and descending to 8,000ft when it rolled over and crashed, killing 64 passengers and four crew, according to the US National Transportation Safety Board (NTSB).

The agency said the aircraft rolled because freezing drizzle created an ice “ridge” on the wing’s upper surface, behind the deicing boots but ahead of the ailerons.

Source: Cirium Dashboard