nav interview question..?!

[high flyer 13]

Which would be easier to navigate only a line of latitude or line of longitude....?

Im thinking a line of longitude because they all run through north so it would be easier to navigate using a compass...!!
Apart from this explanation im sort of stuck for any more else to say anybody else anything to add to this ...??! :\

cheers....

[UAV689]

I think lattitude - same constant bearing the whole time (if there was no wind etc) a line of long is a great circle route and therefore constantly changing direction, yes it goes through north, but not magnetic north!

[Halfbaked_Boy]

I think lattitude - same constant bearing the whole time (if there was no wind etc) a line of long is a great circle route and therefore constantly changing direction, yes it goes through north, but not magnetic north!

But then again, lines of latitude are referenced to true north, not magnetic north, so the same problem applies also!

If you have a HDG(T) readout, I'd say both equally as easy - for lines of longitude hold 360/180 and latitude 090/270.

I'm sure there's somebody much smarter than I who will have a logical answer though. :ok:

[bfisk]

The question doesn't make much sense unless you also say under what circumstances. However meridians are straigth while parallells are curved (except the equator), so my immediate reaction would be the meridians.

[UAV689]

It's defo latitude, that is a constant heading, long is a great circle, which requires constant calculations to fly and has only been able to be done fairly recently (if my atpl memory is correct!).

[Halfbaked_Boy]

UAV689, please see my post above and pray tell what you think!

You could fly a constant heading with reference to magnetic north (this is assuming you are referencing magnetic, and no means to true), but this wouldn't give you a parallel of latitude, even at 090 or 270, because it is referenced to magnetic north, not true.

For example, this is why we have magnetic variation, which applies to ALL headings. This same value also varies geographically, so the error is induced both longitudinally and laterally.

[UAV689]

Don't meridians converge and the angle change closer you get to the poles? Hence if you measure a lat you have to take it mid point do you not as the angle will be different at start or end? The angle is constantly changing, i think!

[Heliskier]

Yes UAV689, meridians do converge near the poles but think about it for a moment. If you follow a meridian from the north pole to the south pole you will always be following 180T, this does not vary with latitude!

[bfisk]

(if my atpl memory is correct!).

It's not.

Parallells of latitude are curved (small circles). Great circles are straight, not the other way around.

Your postulation assumes that you have a true track readout, in which case following a meridian would have you fly 360T/180T instead of 090T/270T - equally simple. However, flying a constant track of 090T/270T requires a constant change of direction. Flying a constant track of 360T/180T does not.

[WELCO]

If that was a question in an airline company interview, then I guess you have navigated away from the area where the interviewer was trying to get you flying at!

Probably you were stuck with it, and so do many others, naturally. There is no definite answer for the question unless you ask some questions first. For instance, what did the interviewer mean by the word "easier"? For the pilot? For flying the company routes? What routes do they fly? N-S or E-W? Crossing hemispheres? Many many variables here.. But guess what.. Aeroplanes with an FMS fly Great Circles effortlessly! Why? Because great cirlces are the shortest way to connect any two points on earth. Meridians are great circles..! & while shorter distance means less fuel plus saving the aeroplane's profitable operating hours, it could be easier for the company too! Does that make sense?! Apparently what could be easier for the aeroplanes to do would be easier for all! So I guess the interviewer was just playing a little game with you trying to present a problem that could have several solutions and probably he is not looking for a particular one, but is rather waiting for you to choose any solution in your head and throw it back to him with good reasonable justification.


Good luck.

[Tojo]

Based on the available information, it would be just as easy to navigate a line of latitude as it would a meridian.
All latitudes are small circles (except the equator which is a great circle) and all meridians are semi great circles - which when considered with their anti meridians make great circles. All meridians converge at the poles and, all lines of latitude and longitute intersect at 90 degrees, therefore any aircraft flying along a meridian or line of latitude will be navigating a (true) cardinal direction becasue they are following a line of constant direction (A Rhumb Line). In practical terms Rhumb Lines are much easier to navigate manually than great circles due the constantly changing direction which is a major characteristic of great circle navigation. So basically just take yer pick - Lat or Long!

Hope this helps :8

[high flyer 13]

thanks for the help guys i hope this question doesent come up but if it does i will be able to give both explanations for lat/long and explain that either one is just as tricky to fly......... :ok: