News  |  Nov 16, 2023  |  Christyn Binder

Navigating the Challenges of Changing Taxiway Designations and Implementing New Signage

This is the second post in a series where we’re exploring the key consideration and complexities surrounding airfield signage. Read the first post here.

Changing taxiway designations and implementing new signage on an airfield can be more complex than meets the eye. In this blog post, we will explore the intricacies involved in modifying taxiway designations, coordinating changes, and implementing new signage systems. We will also discuss the challenges associated with the updated approach and departure surfaces, signage, and markings. By understanding these complexities and taking proactive measures, airports and consultants can navigate these changes smoothly and ensure the highest standards of safety and efficiency.

Changing Taxiway Designations Demands Careful Planning and Coordination

Altering taxiway designations for large capital programs, or any other reason, goes beyond a simple replacement of sign panels. It requires adherence to FAA guidelines outlined in AC 150/5340-18G Section 1.4 and Engineering Brief EB-89A. According to these documents, taxiway nomenclature shall be simple and logical so that letters “A” through “Z” are used first and logically propagate across the airfield.

Ideally, this assignment of designations is performed in a North to South, West to East progression, however care may be needed to skip letters for future planned taxiways. It is also important to note, like most labeling schemes, letters, “X”, “I”, and “O” shall not be used as these designations can be confused with “closed” area directive or numbers. Per the FAA guidance, double letter taxiway designations (e.g. “AA”, “BB”, etc.) shall not be used until all single letter designators are taken. Designators that are similar to runway designations (e.g. Runway 4L vs Taxiway L4) should not be used to avoid potential pilot confusion.

In order for designation changes to proceed smoothly, coordination of changes must transpire between the airport, airport operations, FAA, contractor, and all other stakeholders. Most importantly, scheduling and phasing should be reviewed for all modifications to airfield guidance sign and pavement marking, especially to avoid conflicting designation between phases (e.g. two taxiways of the same designation). Since rehabilitation projects tend to continue for an extended period, slow changes can occur, and temporary solutions may be required. Any temporary solutions require strict compliance that meets FAA guidance and airport safety standards.

Several elements that can be commonly overlooked when changing designations are systems and documentation that may refer to old designations such as an Airfield Lighting Control and Monitoring System (ALCMS) Graphical User Interface (GUI). Although the ALCMS GUI will replicate the airfield graphically with visual feedback of the elements selected/energized, labels and buttons should be checked. If there are old designations, the ALCMS manufacturer should be contacted for a GUI update. Other elements that are also commonly overlooked include airfield electrical circuit labels in the airfield electrical vault and in underground pulling structures as well as asset management and physical labels. If labels use an old designation as a reference or part of the identification tag, care should be taken to update these elements to avoid confusion of maintenance personnel. Unfortunately changing these elements can be much more difficult and old vestiges of past designations may linger for years. The key takeaway is that changing designations can be much more difficult than changing a few sign panels, so be prepared for the extra effort.

Addressing the Complexities of New Approach and Departure Surfaces, Signage, and Markings

Over the past few years, several Engineering Briefs (EB) and Advisory Circulars (AC) have been published revising requirements of approach and departure signage, markings, and protected imaginary surfaces including timelines for implementation. Unfortunately, as of the writing of this document, implementation of signage and marking for approach and departure surfaces are still in a state of debate. Also the criteria under Order 8260.3E US Standard for Terminal Instrument Procedures (TERPS) has not yet been revised to match the latest revision of AC 150/5300-13B. So, what should airports and consultants do to address applications requiring approach and departure surface protections?

First and foremost, talk to your FAA Airport District/Division Office (ADO) contacts since airport signage and marking plans need to be reviewed and approved for Part 139 airport certification. Next, plan for the future!
It might be wise to take into account the new legend criteria in your designs by planning for two signs at approach and departure hold positions to form a multiple sign housing array (e.g. one for APCH legend and one for DEP legend). At first, temporary panels with old legends will need to be installed prior to final panels once the new legend update is finalized. Unfortunately, Pattern A vs Pattern B markings are still being debated. Pattern A markings are the most conservative and require aircrafts to stop and request clearance before passing to avoid a physical conflict between aircraft gear and tail. However, there is a prevailing push for Pattern B markings as shown in revised advisory circulars to reduce tower burden thus only requiring aircraft to hold and request clearance under low visibility conditions. This is similar to a traditional Instrument Landing System (ILS) protected area hold.

Unfortunately, TERPS isn’t expected to be updated to align with current revised guidance anytime soon and the timeline for this update is unclear. Until this update is finalized, it may be advisable to use the old locations for approach and departure surface signage and markings for a more conservative protected zone. By coordinating with your ADO and Air Traffic Control (ATC) staff, operational restrictions may be able to allow your airport to reduce these protected zones per the revised guidance and in some cases remove holds completely if conflicts no longer exist per the reduced surfaces in the revised guidance.

Ultimately, this is a still a complicated situation and evolving issue that requires close coordination with your ADO, ATC, operators, and other stakeholders as discussed in the Implementation Section of AC 150/5340-18G Change 1.

As the aviation industry evolves, so do the challenges associated with modifying taxiway designations and implementing new signage systems. By recognizing the complexities involved, engaging in thorough coordination among stakeholders, and planning for the future, airports and consultants can overcome these hurdles. Clear communication with FAA authorities, careful adherence to guidelines, and a proactive approach to addressing approach and departure surface requirements will pave the way for a successful implementation. Ultimately, prioritizing safety, efficiency, and effective collaboration will lead to an airfield that operates seamlessly and serves the needs of the aviation community. At Arora, we strive to continually improve and innovate in the field of airfield design to ensure the highest standards of safety and efficiency in aviation. Contact us today to get expert guidance for your next airfield lighting project!

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