Nav/ops Proc Question?!!

[stator vane]

studying to take ops procedures and there is a nav question in a set of questions from another school which i am not able to crack open. i've just started the nav section but am scheduled to take the ops dec 4-7. nav next time.

any help with the individual steps would be greatly appreciated.

also if there is anyone in the Newmarket area that would like to help for drinks etc, let me know.

here goes:

"you plan to fly from point A(60N010E) to point B(60N020E). the gyro north of the gyro compass, assumed to operate perfectly, with no rate correction device, is aligned with the true North of point A. the constant gyro heading to be followed when starting from A given that the flight time is scheduled to be 1h30min with a zero wind, is equal to:

A. 076
B. 085
C. 080
D. 066

the answer says A is correct but i don't know if true or how to get there.

thanks again;

[oxford blue]

This is one of the stupidest questions I have ever seen in the JAA exams. Don't get me wrong, I think that pilots should be expected to understand gyro theory. But not with questions like this, which are designed to trap.

Anyway, it works like this:

Earth rate = 15 x sine latitude degrees per hour = -15 x sine 60 = -13 degrees/hour. For a flight of 1.5 hours, this is -19.5 degrees (Negative because in Northern hemisphere).

Meridian convergence (otherwise known as the horizontal component of transport wander) = change of longitude x sine mid-latitude = -10 x .866 = - 8.66 (Negative because you're going Eastwards in the Northern hemisphere).

This totals -28 degrees over the period of the flight.

Now the desired true track between 60N and 60N is 090. But if you maintain 090T, the gyro will read 062 at the end of the flight. If you maintain 090G, the true heading will be 108T at the end.

However, if you set off on 076G and maintain the gyro heading, the true heading will be 104T at the end, giving an average heading of 090T.

Is that silly, or what? But it's the answer they're looking for.

[dolly737]

WOW!

I wonder how sick one's brain must be to invent such a question and desparately hope that this person is not actually flying an airplane - or even driving a car (the chances of which should be very slim anyway - for god's sake)!

[stator vane]

thanks

i could draw it out and came to the conclusion that by taking half of the amount, i could get the answer, but didn't understand the "why."

and to my ears after 5300+ hours leaning on the left window of the 737, this question actually sounded the same as 99.9 % of all the other questions i have read in ALL the subjects thus far.

Meteo should win the award though.

more questions later;

rear guards;