ATPL(H) Air Law question that is boggling my mind.

[darrenphughes]

Hey guys, I'm only a few weeks away from doing some of the exams for the ATPL(H) and have been doing some revision. I came across this question a while back and it raised my eyebrows slightly. Back then I just committed the answer to memory, but now I'm curious.

Q: The radar controller suspects that you are experiencing unlawful interference. What should he do to confirm this with an auto decoder unit? (with no mode A interpretation?)

A: Switch from 7500 to 7700.

So how on earth can a controller decide that we have been hijacked by switching codes on his unit without us indicating it first on our unit? And if we squawk 7500 shouldn't little flashing thingys appear on his screen along with little alarm bells without him having to switch codes on a decoder unit? Any insight would be greatly appreciated. Even if that insight is that I'm a total retard for not getting this totally simple concept!!

On another note, this is the first time I've had something to post in the ATC section of PPRUNE. I'd like to take this opportunity to thank you guys for your support on the ground.

[Radarspod]

That doesn't make a lot of sense! The only way the controller would know if the pilot told him or the appropriate Mode A was set. I would suggest the question is wrong or based on some very old equipment, where auto decoder (plot extractor?) could interpret the pulse replies of the Mode A and display a value - but without a code callsign conversion to convert the Mode A to a meaningful callsign.

Interpreting the question differently could be "The radar controller suspects that you are experiencing unlawful interference. What should he do to confirm this on his display system (without callsign conversion)?

The answer would be to check the Mode A is 7500 - the unlawful interference Mode A code. I don't understand the change from 7500 to 7700 in the answer.

RS

[darrenphughes]

Ok, so on the up side, I'm not a total dumbass!!

[darrenphughes]

Anyone else got anything more on this. Or is it just another question made up by some little guy trying to justify his ridicules salary in a JAA office somewhere?

[VCR]

Makes no sense to me I'm afraid!!

[sr562]

certainly makes litte sense. Perhaps the answer that they are looking for is that the controller should confirm your squawk. I think its in MATS pt 1 that it says if an aircraft squawks 7500 a controller should ask the pilot to confirm he has selected the correct squawk, but not to mention the 7500 squawk, with the 'no mode A interpretation' statement trying to make the question less complicated by removing CCDS from the equation.

[grizzled]

7500 vs 7700

DPH (and everyone else),
You're correct that the question makes no sense. Even if it did, it doesn't make sense for a question on an ATPL(H) exam to require an answer requiring direct knowledge of ATC internal ops/procedures.

In any event, I can tell you with conviction that you will no longer find that question on the exam.

Grizz

[darrenphughes]

In any event, I can tell you with conviction that you will no longer find that question on the exam.

Cool, I'll just assume you have some insider knowledge in this area!!

Thanks to all the responders.