The new Hamilton Khaki Aviation Converter Auto features a circular slide rule, similar to Breitling’s Navitimer. The Hamilton watch costs less. Let’s take a look at the differences.

For decades, Breitling has constructed a lot of its reputation on the Navitimer with its circular aviation slide rule. In the company’s new course with Georges Kern at the helm, the Navitimer is still there, but it’s no longer the dominant focus. Now Hamilton have stepped into the fray, offering a lower-cost aviation watch featuring a circular slide rule. The Breitling Navitimer Automatic costs from €3,920, the Hamilton Khaki Aviation Converter Auto starts at €1,045.

Hamilton vs Breitling, two circular slide rule watches compared

You can’t avoid comparing the two watches. The Breitling Navitimer Automatic is beautiful for the legibility of the slide rule. I know these things are a question of personal taste, but personally I think that for a technical, tool watch such as this, black and red numerals and scale markings on a light background are the best way to ensure legibility. Hamilton have chosen to reinforce the pilot’s watch image by means of a black background and white indications, and while this enhances legibility of the basic time indications, the fine detail of the scales suffers somewhat. It’s simply very difficult to read red lettering on a black background.

Rotating bezel

There is also a difference in the rotating bezel. The Breitling version is distinctive for the use of beading. Its fine texture gives it an almost jewel-like appearance. Hamilton have opted for a more visible knurling with a high gloss finish, and the same texture is used for the crown. It creates a tougher and more masculine appearance.

The Breitling bezel rehaut is flatter and the two scales are in direct contact one with the other. The Hamilton has a steeper rehaut and there is a gap between the two scales. This is because in the Hamilton version, the outer scale is outside the watchglass, and the space between the two scales is where the watchglass fits into the bezel. In the Breitling Navitimer, the watchglass extends right to the outer edge of the bezel so that both scales are underneath and can be in direct contact one with another.

Aviation romance

I know what you’re thinking, heck, no-one is ever going to actually use the circular slide rule for calculations and conversions for airspeed, distance, fuel consumption and so forth, it’s just a romantic throwback to the glorious Fifties, just before the start of the digital revolution. So the principal objective of the bidirectional rotating bezel and its circular slide rule is that it should look good. And the Hamilton Converter does that fairly well. I like the contrast between the simplicity of the central part of the dial, and the dense complexity of the bezel.

Hamilton Converter Auto technical features

Technically the Hamilton Khaki Aviation Converter Auto is impeccable considering its price level. Hands and indices are coated with luminescent paint. The H-10 movement is self-winding and provides an excellent 80 hours of power reserve, and it offers some resistance to magnetic fields because the balance spring is in Nivachron alloy. The movement can be viewed through a display caseback. The watch has a 42 mm case providing a 10 bar, 100 metre water resistance, making the Hamilton Converter Auto perfect as an all-weather watch capable of resisting rain, splashes or even being accidentally dropped into the water. It comes on a stainless steel bracelet, you save €50 if you choose the version with a leather strap, but I think that it looks better on the bracelet. A version with black PVD case provides a stealth-type look.

So the Hamilton Khaki Aviation Converter Auto is a Swiss-made watch at an attractive price considering the amount of engineering and design in the case and bezel. The Breitling Navitimer Automatic costs almost four times as much. But you can see the difference.