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Whenever I watch cockpit footage of test flights there is always an added device with big clock-like digits centered above the glareshield.

They come in different shapes as shown below. What are they called and what are they for?

I'm thinking it's to timestamp the multi-angle video cameras, but I highly doubt that's the answer.

enter image description here

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Images linked to sources.

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  • $\begingroup$ The device on the third picture is a display. $\endgroup$ – mins Oct 4 '16 at 22:33
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    $\begingroup$ @wbeard52 On the off chance that you see this, you are aware that :// is valid at the start of a link URL, right? It resolves to the same protocol the referring page was loaded over, so if someone browses Aviation over HTTP it gives the images over HTTP, and if they browse over HTTPS then it gives the images over HTTPS, thus avoiding mixed content warnings and any possible HTTPS overhead for those who really want HTTP. It works here because in this case, identical content can be served over both. $\endgroup$ – user Oct 5 '16 at 15:38
  • $\begingroup$ The cameras I've seen for flight tests are pre-synchronized to UTC time. The display also often has UTC time displayed somewhere on it, and an old-fashioned clock may also be present in the cockpit. I know time synchronization of flight test data can be tricky but I don't see the point of displaying the time in another place on the cockpit. $\endgroup$ – Cody P Oct 5 '16 at 19:40
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enter image description here

From YouTube

After scouring the internet, the device seen in the first two pictures is indeed a clock.

In the linked video the display does count up like a clock. In the beginning of the video the narrator says, "it's just after 4 AM in Seattle," and the displayed time is 04:17:58.

Watching the maiden flight of the A350, no similar device is found.

I then turned my attention to the FAA's Flight Test Guide For Certification Of Transport Category Airplanes, there's no mention of such a device being mandatory.

Closest thing I found is a requirement to video record and timestamp spin tests in light aircraft.

The timestamping theory would make sense if the video recording of the cockpit is high speed, which would be overkill for any scenario really.

Time synchronization for the flight test instrumentation data acquisition is a real, and complicated thing.

My theory, showing the pilots the master clock—if that's the case—would help the pilots note the time when a situation arises so the engineers can check the relevant data.

It might also have other functions as recording total elapsed time of the entire flight test program for the airframe it's installed on.

I've also looked into trajectory guidance systems for test pilots based on true airspeed/pressure measurements being fed to the pilots, but such systems turned out to look completely different than a seven-segment display.

Over to you.

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