Justin Litke

How to use the Chronometer

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This may seem like a fairly basic question, but I can't find the answer anywhere. How do you use the cockpit clock/chronometer? All I can do is get it to show the date in various ways, and the chronometer will only show minutes, I can't even understand what the hold/stop button does. Can someone write a guide explaining how?

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I believe it depends upon which chronometer is in the instrument panel. You haven't mentioned which aeroplane. Some of them show zulu time, some show local time as well as elapsed time (that's the one showing minutes, unless you fly for longer). Some will have the stopwatch function. Some chronometers are better modelled than others.

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It will depend on which cockpit chronometer you are referring to, and what you are trying to achieve with it. Generally speaking, you'll only need to have the chronometer display minutes, since a chronometer is typically used for timing IFR maneuvers and if you are using it to log hours, it's easy enough to work out anyway. There are some specific things it is used for though...

For example, you can time the legs of a holding pattern by starting the chronometer when you pass over the nav aid which marks the hold, fly out on the hold heading radial you have been advised to follow, and then make the 180 degree turn for the racetrack holding pattern when your chronometer reads one minute, using a standard rate turn (use one minute legs if you are below 14,00 feet, if you are above 14,000 feet, your legs should be one and a half minutes long).

This is also why your turn and slip indicator has a needle which will (typically) read 'two minutes' unless it is something like a fast jet. That's telling you that if you perform a properly coordinated turn using the calibrated markings on your turn and slip gauge, it will take you two minutes to perform a complete 360 degree turn, since the gauge is calibrated to line up those markings when you are turning at a rate of 3 degrees per second. So if you make a rate one turn in a hold, your turns will be one minute long and your legs will be one minute long as well.

If you want to know how good or bad you are at making precise turns (note that this is also one of the ways to test if the flight model is any good on an add-on aeroplane), start the chronometer and commence a rate one standard turn, (i.e. keep the ball centered on the slip indicator and keep the needle pointing at the main turn marking, if you have autorudder on in your sim options, the sim will do this for you). If it takes you thirty seconds to turn 90 degrees, you are flying a rate one turn accurately and the flight model of the aeroplane is probably pretty good if it does a rate one standard turn properly.

You can, if really stuck, use the chronometer to time a descent for a landing when at the proper three degree descent angle if you are flying toward or away from a recommended nav aid in poor visibility, to ensure you will clear any raised terrain or obstacles marked on a chart as you come down.

Commercial flights and test flights will occasionally start the chronometer when commencing the take off roll in order to facilitate accurate record-keeping for log book purposes. Of course that doesn't really matter in a flight simulator, but you might want to do so anyway.

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