Part 135 Ground De-Icing: Building a Program Before Winter

The foundation of every winter operations program is the clean aircraft concept: an aircraft must be free of frost, ice, and snow adhering to critical surfaces before takeoff. Contamination on a wing degrades lift and increases stall speed in ways that are not proportional to how the contamination looks from the ramp.

Part 135 addresses this directly, prohibiting takeoff when frost, ice, or snow is adhering to wings, control surfaces, propellers, engine inlets, and other critical surfaces. The rule is written as a prohibition rather than a recommendation, and accident history is unambiguous about why.

Because the specific text has been amended over time, including provisions relating to frost on certain surfaces, read the current rule directly rather than relying on institutional memory of what it used to permit.

An operator that wants to depart in conditions conducive to ground icing generally needs either an approved ground de-icing and anti-icing program in its operations specifications, or must comply with the alternative pretakeoff contamination check requirements the rule prescribes.

The approved program route is what allows structured use of holdover time tables, where a treated surface is considered protected for an estimated period based on fluid type, concentration, precipitation type, and temperature. Without an approved program, an operator loses that structure and is left with a far more restrictive practical envelope.

The choice has real operational consequences in the winter, and it should be made deliberately in the summer, when there is time to build the program, train people, and get it approved.

A complete program addresses management responsibilities and who has authority to make de-icing decisions, along with the fluids used, their concentrations, and the holdover time guidance applied to them. It defines the procedures for de-icing and anti-icing, including the sequence and communication between crew and service personnel.

It covers the pretakeoff check and the pretakeoff contamination check, specifying who performs them, from where, and within what time window relative to takeoff. It defines communication procedures so that the crew always knows exactly what treatment was applied and when it started.

It also covers training and qualification for every person involved, including flight crew and any contracted ground service personnel, and it defines the records that demonstrate all of this happened.

Holdover time tables give an estimated period of protection after anti-icing fluid is applied, based on fluid type and concentration, precipitation type and intensity, and outside air temperature. They are planning tools built on test data, not promises about a specific airframe in specific conditions.

The most important discipline in using them is that the crew remains responsible for the condition of the aircraft at the moment of takeoff. If conditions change, if the holdover window lapses, or if there is any doubt about the state of a critical surface, the answer is to check and if necessary treat again.

Programs that fail in practice usually fail here: the tables are in the manual, but the decision culture treats an unexpired holdover time as authorization to go rather than as one input into a judgment the crew still owns.

Most charter operators de-ice at airports they do not control, using personnel they do not employ. That is normal and workable, but it means the program has to extend to those relationships explicitly rather than assuming the FBO's competence.

That means knowing which fluids each location actually stocks and at what concentration, confirming that the people applying them are trained to the standard your program requires, and defining exactly how treatment details get communicated to your crew and recorded.

It also means having a defined answer for stations where adequate service is not available, decided in advance rather than negotiated on a cold morning with passengers waiting.

A winter operations program is a manual system, and manual systems drift. Fluid guidance is updated, holdover tables are reissued, operations specifications are amended, and vendor arrangements change from one season to the next.

The failure mode is not usually a missing program. It is a program that no longer matches the current guidance or the operation's actual footprint, and nobody noticed because nothing forced a comparison.

Mapping each manual procedure to the requirement it satisfies is what turns that from an annual scramble into a maintained state. That mapping, gap detection, and corrective-action tracking is exactly what Navlyt does with your operations manuals.