JAR Exam. INS Accuracy.

[Snoopy2]

Hi,

I wonder if some expert can help with the correct answer to the following question and explain why?

Thanks.



An INS has an accuracy of 0.01°/hr. After 12 hours flight with a ground speed of 500 knots, what is the maximum off position.

a) 12 b) 6 c) 2 d) 1.2

[oxford blue]

This question has been removed from the JAA question bank as a result of a complaint from Oxford (about 2 years ago!) to the CAA that it was an unreasonable question (and also that the JAA had the wrong answer marked as correct -which happens from time to time!) If your FTO is still putting it out as feedback, their feedback is out of date. This one should never appear in the exams again.

An explanation of the answer is at the following website:

:

http://www.v1rotate.freeuk.com./downloads/INerror_Solution.doc .

There was a previous correspondence on pprune about it, which can be found here (http://www.pprune.org/forums/showthread.php?s=&threadid=7594)

[Snoopy2]

Many thanks for your reply.

This question has just come up in JAR exams in Switzerland.

A friend of mine has just missed the last JAR subject needed (by only one point), because of this question. The exams are necessary to convert an IACO licence to a JAR licence, and secure a job on offer.

Said friend is an experienced jet Captain and tried to convince the Examiner that the answer was 6NM, not 12NM, but could not explain it to the satisfaction of the Examiner. Language differences may have contributed to this.

Over the last weekend the question has been discussed at length with various friends. Some can understand that the answer is 6NM but cannot understand the theory behind it (I didn't understand it fully myself), hence my original post.

Hopefully with your information an appeal for the JAR subject will be successful.

[oxford blue]

I hope so, too. I am disappointed to see the question still in existence, but I believe that it has been blocked from the UK version of the question bank.

If anyone has seen this question in an actual UK exam in the last year or so, please post a message on this thread and I'll get back to the CAA.

[Snoopy2]

A million thanks for your help.

Not sure if the question has been removed from the database in Switzerland but your explaination did help my friend pass the exam.:ok: :ok: :ok: :D :D :D

You can probably see the grin from there.