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Exercise 3.2 Q.20
liawks
Topic Author
liawks created the topic: Exercise 3.2 Q.20
Dear Bob,
I'm a little confused with the answer given. I chose answer as A: none but the correct answer given in the book is C: 20 minutes holding may be carried.
The OPR visibility is 6000 RA whilst the alternate minima is 6km.
ENR 58.2.1b says: visibility - less than the alternate minima;
In this case, they are equal. Hence, the confusion.
The TAF says that there is SCT cloud with a base of 1000 feet and FEW cloud with a base of 800 feet. That means that there is more than 4/8 of cloud below the alternate minimum of 1200 feet [AIP ENR 1.1 58.2.1]. The TAF is forecasting conditions below the alternate minima until 0400 because of the cloud. [As you correctly noted, it is not the visibility that is the problem]. If you can hold until 0430, you will not need an alternate. Your ETA is 0410, so need to be able to hold for 20 minutes until 0430. AIP ENR 1.1 58.2.3
