According to FAR 91.205 (d)(6), one instrument required for IFR is:
A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation.
Why is it necessary to time things in the cockpit, or know the time?
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Sign up to join this communityAccording to FAR 91.205 (d)(6), one instrument required for IFR is:
A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation.
Why is it necessary to time things in the cockpit, or know the time?
There are several reasons:
All of these scenarios are discussed in detail in the FAA's Instrument Flying Handbook and in the AIM.
In IFR the pilot needs to have a second-accurate time indicator for a variety of maneuvers.
For example, the standard holding pattern is 1 minute turns and 1 minute straight legs. Having the number of seconds allows the pilot to fly these maneuvers accurately.
When flying under IFR in IMC you have no external visual references, so there are a number of reasons you may need to time something:
There may be others but these are the ones that spring immediately to mind.
Some procedures require timing, e.g. holding over a fix or NAVAID is usually done in 1min legs. Precise timing is necessary here. Some clearances can also contain a time (e.g. release valid until, revised approach time, etc), where correct timing is necessary.