My Eastern Watch Collection: Hamilton Khaki Aviation X-Wind Auto Chrono H77906940 (similar to H77916920) - This Watch Does Have The Look, A Review (plus Video)

I have been eyeing the Hamilton Khaki Aviation X-Wind Auto Chrono ever since it first debut back in 2016. Granted the special complication that the watch was designed for would not be useful to me, I was taken more by the beauty of the design than anything else.

The number of pushers and crowns on the watch intrigues me. Having two inner bezels as well as an external bezel in a watch appears to be an overkill. Nevertheless, the watch has a few ingenious use of the moving parts of the watch to do rather complex computations. In reality, the Hamilton Khaki Aviation X-Wind Auto Chrono (the X-Wind for short) is a mechanical computational device that is already obsolete when computers are already taking over the same job and more.

Looking passed the question of efficiency, you start to appreciate the way form and function designed into the watch would be able to do such calculations. To me, what makes this watch desirable is the way a mechanical 'calculator' has been made to look like a brilliant piece of art. The X-Wind should be in the collection.

Unfortunately when this concept was launched by Hamilton years ago, the brand's footprint in Malaysia was not that wide and the only feasible option was via Amazon. After a few years, Hamilton has become more established in this part of the world and I was able to get one from a local authorized dealer. I decide on the latest 2021 offering and the model I got was the H77906940.

The Current Series

The first Khaki Aviation X-Wind was developed with French pilot Nicolas Ivanoff, an aerobatics pilot and and long-term participant in the famous Red Bull Air Race circuit. The concept of the watch relies on the need for pilots to calculate the correct drift angle according to wind direction.

The most famous model of the Hamilton Khaki Aviation X-Wind Auto Chrono series was the H77616533 was launched to the general public in 2016. That watch was worn by Jake Morrison, played by Liam Hemsworth in the movie Independence Day: Resurgence also in 2016. Due to this product placement, a lot of people had the impression the series only started in 2016.

Based on my research, the Hamilton Khaki Aviation X-Wind Auto Chrono was first introduced in the 2010 Hamilton Catalogue. There were five models with the same general shapes, controls and functionalities (mechanically calculating the wind drift angle). The models are with reference numbers H77616133, H77616333, H77616533, H77626153 and H77696793. Interestingly, all were powered by standard Valjoux 7750. [Note: This information still needs to be varied. I have not found any definitive date when the first Hamilton Khaki Aviation X-Wind Auto Chrono was introduced.]

After a few iterations, in 2021, the brand issued a refresh with two new models: the H77906940 and the H77916920. The significant change is a new chronograph movement, the H-21-Si. Hamilton was able to introduce a silicon balance spring (hence the additional '-Si' prefix) to enhance the anti-magnetic property of the original movement (the H-21 which in turn was based on the Valjoux 7750). Magnetic interference is generally more pronounced around airports due to the concentration of x-ray machines and radar antennae. To be able to reduce the risk of magnetic interference is definitely welcomed.

Below are the two new members of the 2021 iterations.

H77906940
Auto Chrono Blue
Sunray blue dial
Natural stainless steel
Textile strap in blue
RM8,150

H77916920
Auto Chrono Sandstorm
Beige camouflage pattern dial
Sandstorm Beige PVD coating
Textile strap in beige
RM8,800

Of the two, the Auto Chrono Blue is the more practical in terms of colours. Hence, I chose that instead of the Auto Chrono Sandstorm.

The Watch

Although aviation themed watches came to the forefront during World War 2, Hamilton's foray into the genre has a more modern origin. Despite having established in 1892, Hamilton only started a strong involvement in the aviation arena in 2005 when it took part in air shows like the Red Bull Air Races.

The X-Wing is built as a tool watch for pilots. Typical of pilot watches, the stainless steel cased watch is big at 45.0 mm wide with a lug-to-lug length of 55.0 mm. Coupled with the height of 14.9 mm, the X-Wing sits loud-and-proud on the wrist. There are many surfaces on the watch. Some have polished finishing while others have brushed finishing.

Like dive watches (versus dive computers), although the technology of the X-Wind is obsolete in view of modern electronics, it is a good backup tool in case the primary device fails.

The X-Wind has a Destro watch styling i.e. having the time adjustment crown (generally known as the primary crown) on the left of the casing. Destro translates to "right" in Italian which is the wrist where a left-handed person would typically wear a watch. This is the first time I came across this term while researching about this watch (there is always something new to learn 😀). However, what I was made to understand is that the designers in Hamilton put the cross-wind calculator crowns as the 'primary' controls while delegating the rest as secondary. Hence, the Destro styling. This watch is still meant to be worn on the left hand allowing the right hand to easily manipulate the calculator crowns.

The dial has a brilliant cobalt blue sunburst colour and is very busy. The uncommon 12-3-6 sub-dial layout owing to the rotated H-21-Si movement also accounts for the day/date display to be located at the unconventional 9:00. The complexity is made more pronounced with the addition of the two inner rotating bezels. Hamilton opted for a rather wide inner bezel which limits the rest of the usable dial space for the rest. This is to ensure the complex numerical scales especially on the inner bezel is legible. Hence the actual usable dial surface only has a diameter of 29.0 mm where the minute and hour markers, the date/day aperture, the sub-dials and the texts are actually placed. To give this some perspective, this means only 41.5% of the top surface is used for the dial itself.

The sub-dials have flight instrument-inspired timing scales with deep layered effect. The sub-dial at 12:00 is the 12-hours chronograph counter, the sub-dial at 3:00 is the sub-seconds and the sub-dial at 6:00 is the 30-minutes chronograph counter. Meanwhile, for the indices at the four corners of the compass, Hamilton chose applied squares with a triangle at 12:00. For the rest of the hour markers, Hamilton uses bold printed Arabic numerals and sub-seconds scale. The polished syringe handset as well as the sub-dial hands are sufficiently sized for ease of reference.

There are four lines of text on the dial. The brand, the model name, movement type and the manufacturing origin are all printed around the date/day aperture and at the bottom of the dial. Meanwhile, the day/date aperture have a bevel cut to the edge and framed with a white box. Both the date and day wheels have black fonts over a white background.

As highlighted earlier, the X-Wind has two internal rotating bezel with multiple scales. Unfortunately, I am not conversant with the calculating method hence I have included the manual in PDF format at the end of the review. Please refer to it if you want to know more about the way to calculate the wind drift angle.

Protecting the dial is a flat piece of sapphire crystal with anti-reflective coating. Surrounding the crystal is the bi-directional bezel. Like the internal bezel, there is a unique scale on it that is part-and-parcel of calculating the wind drift angle.

The X-Wind has six (6) control surfaces (if you also include the external bi-directional bezel). The crown that controls the time adjustment and manual winding is at 9:00 and is a screw-down. The crown design is chunky with wide gear-tooth and signed with the Hamilton logo. At 8:00 and 10:00 are the two pushers for the chronograph function. Due to the need to rotate the movement to put the controls on the left side of the casing, the chronograph's start/stop function is the pusher at 8:00 and the chronograph's reset function is at 10:00. Meanwhile, at 2:00 and 4:00 are the two screw-down crowns to control the two inner rotating bezel. The 2:00 crown controls the bottom inner rotating bezel while the 4:00 controls the top inner rotating bezel. Both crowns are similar in design to the time adjustment crown. When screwed down, all three crowns sits in a slot protected by protruding shoulders.

Meanwhile, another flat piece of sapphire crystal is also used to cover the display screw-down case-back. Unlike the previous models, the 2021 version comes with a full display window. The previous models have a half window where a chart is etched on the metal part of the case-back to find the crosswind component. For the 2021 model, a separate card with the chart is provided. Personally, I was disappointed with this change. I would prefer the chart be included as part of the case-back.

Powering the watch is the H-21-Si, an evolution of the robust 7750 architecture. This caliber has an anti-magnetic silicon balance spring. Operating at 28,800 BPH or 4 hertz, it has a power reserve of approximately 60 hours.

The watch casing has a water rating of 10 bars or 100 meters. This is more than adequate for the intended role of this watch.

The watch is paired with a thick blue textile strap. It measures 22.0 mm at the lugs and has two rivets at at both ends near the lugs. There are two strap guides, one fixed while the other is free to move. A simple signed buckle with a single pin connects the two parts of the strap. A strip of leather protects the pin holes from fraying. From a comfort point-of-view, it does take some wearing time to slowly release the stiffness in the strap.

Below is a photo of the watch in the dark. All hands (including the dub-hands) as well as hour markers are painted with Super-LumiNova paint.

The Wearing Experience

I love sports watches. I feel very comfortable wearing the X-Wind. It may look big on the wrist but this is not unexpected considering it is a tool watch. Even at this size, the amount of information on the dial and bezels is a lot and does make it difficult to see them properly.

The strap is stiff straight from the box. It takes a week or two of wearing the watch to soften the strap.

I have to confess that the only complication that I would ever use on this watch would be the chronograph function. Nevertheless, the thought that the X-Wind can do the wind drift calculation is impressive - useless to me but excellent to have as part of horology history.

The major gripe I have is the transfer of the crosswind graph from the back of the case (in the previous iterations) to a separate card (see the next section for a photo of the card given). This is a bad move in my view. I bet the reason it was changed is so that one do not need to take the watch off the wrist to do the calculations. In reality, most people will take off the watch from the wrist as the process of calculation is a two-handed affair (plus a fair amount of close-proximity-to-the-eyes to see the small numbers being referred to on the internal and external bezels). As such, flipping the watch over to refer to the crosswind graph is almost natural - more natural than trying to find the printed card which could be anywhere. Moreover, the design of the half-window and the etched graph on the other half is so unique to the X-Wind genre.

The last issue I have is the inability to use any of the scales provided on the bezels (internal and external) for other functions. Generally, bezel equipped watches can double as a countdown timer or a GMT. Unfortunately, due to the uniqueness of the algorithm for the wind drift angle mechanical calculator, all the scales are non-linear. Hence the problem of using these scales to track time.

Despite all the issues highlighted, the watch remains impressive as a tool watch. Sometimes, the purpose may not be all that useful but how it looks count too. This watch does have the look.

The Packaging & Door Gift

The official packaging is made out of three parts. The white cardboard sleeve; the packaging box where the primary watch-box and documentation sit; and the primary watch-box itself.

Inside the manual is a credit card sized plastic piece with a print of the crosswind graph. This card is an important component that you need to have with you if you want to use the watch to calculate the wind drift angle.

Interestingly, when I went to collect the watch from the vendor, instead of being placed in the official watch-box, it was kept in a unique clear plastic storage container. I was made to understand from the shop that this is how watches are shipped to authorised dealers.