The design of San Francisco International Airport’s (SFO) air traffic control tower was commissioned in 2012 replace the original aging tower.  A total of 10,000 square feet of 4mm Alucobond® Plus in custom SFO Silver color clads this spiraling torch-shaped structure.


This iconic tower concept design was the collaborative work of SFO and HNTB Corp., who served as master architect for the project. Detailed design work was completed by Fentress Architects, who served as architect of record and worked in a design-build capacity with general contractor Hensel Phelps Construction Co., Walter P Moore, served as structural engineer. The 1,500 System A Alucobond panels were installed by Pacific Erectors, Inc.

The Process


While the tower’s cladding originally was specified with 3/16” aluminum plate panels, we felt that Alucobond ACM would be better suited to handle the specific challenges presented by the tower’s geometry. Alucobond is the only surface material that has the flexibility to be formed into these complex shapes.



To create this series of complex panel shapes, we utilized Autodesk Revit Building Information Modeling (BIM) software and the architectural 3-D printed models; we also created a series of nine panel assembly and fabrication prototypes and two full-scale mock-ups.

When we started modeling and prototyping, we discovered the tower geometry was dictated by a set of very specific mathematic rules, this allowed us to confirm every dimension on each panel pulled from the model mathematically to ensure the panels would fit on site. This was an exhaustive process requiring manual input and calculation of hundreds of points along the perimeter of each panel. While this process validated the theoretical model and was used in prototyping, it wasn’t practical for full-scale production. We searched for software that would provide an automated flattening solution but were unsuccessful. In the end, we employed a developer to build custom software for us. We relied solely on 3-D modeling to fabricate the Alucobond panels eschewing field measurements.


The challenge faced by Pacific Erectors’ in correcting site tolerances during panel installation while hanging from a swing stage was monumental.  They also had to accomodate hundreds of anchors and lightning protection penetrations located in reveals with only 1/16” tolerance.

In the end, every panel fit, every single panel was built from the mathematically corrected Revit model without relying on field dimensions. That’s an incredible testament to the capability of BIM-based construction.

This was by far the most challenging project we’ve ever completed as a company, and the most extreme in terms of geometry and modeling.


“The final, stunning installation is a testament to KPS and their ability to model the surface, develop custom software to translate model information for digital fabrication, and accurately fabricate the complex panels to incredibly tight tolerances. Thanks to KPS for making this iconic vision a reality!”

Ned S. Kirschbaum | FAIA, CCCA, LEED AP BD+C
Principal, Technical Design Director, Fentress Architects