Blog

To spray or not to spray the vertical

July 14, 2024

Have you ever wondered why some aircraft taxiing away from a de/anti-icing operation have vertical stabilizers that are painted yellow or green because of a Type 2, Type 3, or Type 4 fluid application while others don’t?

Thickened fluid applications are permissible on vertical aircraft surfaces such as the vertical stabilizer, rudder, winglets, and fuselage as per global deicing standards, regulations, and aircraft manufacturer guidance, however the ultimate decision to apply thickened fluids on these surfaces is often specific to the approved ground deicing program of a given airline. In short, some airlines require vertical surfaces (most notably the vertical stabilizer) to be sprayed with thickened fluids while others don’t, and both approaches are acceptable.

The employed procedure also tends to have a geographical variance, with operators in the United States, Europe, and Asia often requiring anti-icing of the vertical stabilizer, while those in Canada, for example, do not.

There are numerous reasons for not spraying vertical surfaces like the stabilizer, such as a lack of holdover time for fluids applied to vertical surfaces and an increased likelihood of fluid ingestion in the APU inlet or tail pitot systems (on some aircraft such as the B737) when anti-icing fluids are applied to the stabilizer.

In our SureOps Ground Deicing Program, which harmonizes the procedures employed by the carriers who approve the program, the de facto approach is to NOT spray fluids on vertical surfaces, unless requested by the pilot in command.