One thing seems certain -- this is not what we call a "Transitional" case.

Lugs on Transitional case have two primary surfaces -- top and side. See the two photos below.

The Autavia being sold by Phillips seems to have the "third" surface between the top surface and the side surface. I believe that this third surface would be called a "chamfer" or a "bevel". Whatever it is called, it is a third surface, that connects the two that are perpendicular to each other (the top and the side).

So this seems to be the usual first execution screw-back case.

I would like to do some further work to see how often we see the Tachy-on-Dial in this case . . . but that is another issue, at least for the moment.

Jeff

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: Interesting to see this Autavia, being sold by Phillips,
: November 7 and 8, in Geneva.

: Here is the catalog listing .

: The description appears to be a bit jumbled . . . Deriving its
: name from the combination of the words “automobile” and
: “aviation”, the Heuer Autavia chronograph wristwatches from
: the 1960s were often found on the wrists of professional racecar
: drivers. First came the 1st execution, Autavia, presented in
: 1962, which was the first chronograph wristwatch by Heuer to be
: given a model name.

: The present Autavia Reference 3646 bearing serial number 82848
: (from the mid to late 1960s) is particularly special, as it
: is believed by scholars to be the first known example to be
: fitted with a transitional screw-down case back.

: The other important difference on this rare example is the
: tachymetre dial. Most reference 3646 have plain dials, and
: research shows that only about 15-20 examples of the 3646
: with this outer tachy scale are known to date. It was
: thought to have been a special order dial, hence why so few are
: seen today. Although serial numbers and case back engravings
: once seemed insignificant to your average collector, in
: today’s world of collectible wristwatches it has been seen
: time and time again that those numbers could in fact prove a
: watch’s origin.

: During the evolution of the Autavia screw back case model, the
: case, dial, and hands saw many subtle changes, known in the
: community as “executions”. This watch is the third
: execution “transitional case”, which covers a short period
: of circa 500 or so serial numbers. The biggest difference
: between this case and the standard third execution case is the
: straight finish on the lugs, the standard cases having bevelled
: edges. The other thing to note is the transitional case has
: a wide bezel, which is similar to the first execution (Note
: the transitional case does not take a thinner bezel, normally
: found on the third execution).

: This watch is a true treasure for any Heuer enthusiast with its
: combination of a transitional case with a tachometer dial,
: making it a very rare and highly collectable watch.

: It will be interesting to see how it goes with this one.

: Jeff

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