Deicing Safety Alert
The National Transportation Safety Board issued Safety Alert SA-097 ahead of winter in the Northern Hemisphere, reminding operators that flying in icing conditions can present operational risks, including the adverse effects of airframe and propeller icing on aircraft performance, which can make managing the airplane’s flightpath and airspeed more difficult and can prevent the airplane from maintaining level flight.
As little as ¼-inch of wing leading-edge ice accumulation can increase the stall speed by 25 to 40 knots and cause sudden departure from controlled fight, according to the alert, which adds: Ice accumulation on pitot tubes can cause flight instruments to cease operating and can affect airspeed, altimeter and vertical speed indicators.
The NTSB says: Some pilots have been taught to wait for a prescribed accumulation of leading-edge ice before activating deice boots to alleviate ice accumulation on flight control surfaces because of the believed threat of ice bridging. However, performance degradation could develop if the deice boots are not activated as soon as icing is encountered.
The notice also warns that many pneumatic deice boot systems have no provision for continuous operation and require pilots to manually cycle the systems. Continuous use of the autopilot in icing conditions can deprive the pilot of the opportunity to detect the buildup of ice on the airframe through changes in longitudinal trim requirements and control forces.
What Can You Do?
- When operating in icing conditions, use the autopilot only as directed by checklists and aircraft manuals, which might call for periodically disconnecting the autopilot to better feel changes in the handling qualities of the aircraft.
- Maintain the recommended airspeed for flight in icing conditions as specified in the POH.
- Activate leading-edge deice boots and pitot heat in accordance with the POH.
- While icing conditions exist, continue to manually cycle the deice system unless the system has a provision for continuous operations.
- Review your POH for specific operational requirements to determine the most effective means of shedding ice.
- Closely monitor windshield, windshield wiper, engine air inlets and wings for ice accumulation, and do not hesitate to leave icing conditions as soon as possible to avoid ice accumulation.
- Be aware of the potential for icing conditions and use all checklists associated with operations in such conditions.
Source: National Transportation Safety Board
NTSB Special Investigation Recommends Safety Improvements for
Part 135 Operators
A special investigation by the National Transportation Safety Board of more than 500 accidents involving Part 135 operations between 2010 and 2022 has resulted in the NTSB issuing three new and two reiterated recommendations to improve safety.
The investigation initiated in 2022 after a cluster of safety issues emerged from recent investigations of accidents involving Part 135 operators, including commuter air carriers, air tour operators, air ambulance services and on-demand business charters, among other operations. The report did not look at Part 121 major airline operations.
Safety issues explored in the report include:
- Unsafe loading conditions. Investigators cited four single-engine airplane accidents where unsafe loading conditions were identified. The NTSB said that a requirement mandating flight manifests and weight and balance documentation be recorded for all aircraft operated under Part 135 would help pilots detect and correct unsafe loading conditions. Such a requirement would also provide operators and inspectors the information needed to support proactive, comprehensive assessments to identify any related operational risk areas that may influence improper aircraft loading and mitigate them before an accident occurs.
- Lack of certificated dispatchers for some operations. The report identified 12 accidents in which flight dispatch and operational control were deficient because the personnel responsible for those areas were not certificated flight dispatchers nor did FAA regulations require them to be. The NTSB said that certificated flight dispatchers would expand the safety margins of many Part 135 operations because of improved quality control over functions such as preflight weather, fuel and route planning, active monitoring of conditions along the route of flight and timely notification of emergency response organizations if an aircraft is overdue.
- Flight data monitoring. The report noted that flight data monitoring programs could provide Part 135 operators with objective information on how their pilots conduct flights, and a periodic review of such information could assist operators in detecting and correcting unsafe deviations from company standard operating procedures.
The NTSB also called for needed improvements in the collection and reporting of aircraft accident and flight activity data used to determine accurate accident rates for certain segments of Part 135 on demand operations. The NTSB is pushing for enhancements to data collection so it can better target safety initiatives. The full Special Investigation Report AIR-24-03 is available at ntsb.gov.
Source: National Transportation Safety Board