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9th Jan 2019, 18:19
ajl165

Join Date: Sep 2017
Location: Europe
Posts: 13
Help - ROC/ROD calculation

Hi guys,

I've ran into this during selection process for ATC and it's been bothering me. Maybe you can give me explanation for dummies.
We were given an exercise where we had the following information provided:
- two aircraft, their rate of climb/descent was known and flight levels they were at and flight levels they were climbing/descending to ...
E.g. Aircraft 1 - FL 300 climbing to 400, rate of climb 1000ft/min, Aircraft 2 - descending from FL 350 to 250, 1000ft/min ROD
Now, those planes were flying either towards each other or behind each other on the radar and we had to determine whether they were gonna "overfly/underfly" before passing each other/before reaching passing point.
On the radar screen you could see their speed and also how far away they are -- you could determine whether they were let's say 5 minutes apart.
Supposedly there were more than one way to make the calculation.
One of the easiest ways was apparently calculating difference of FLs and then dividing it from ROC/ROD?!? That way we should've found out how much time it will take for the planes to climb or descend and then compare it to radar data.... So let's say our calculation would tell us that planes will reach their FLs in 4 minutes and they were 5 mins apart on the radar, then we would have to answer that yes, they will overfly/underfly each other before passing each other/before reaching passing point - the point where they meet.
Anyway, does that make any sense to you? How would you work with that? How to calculate this step by step?
Now we had about 30 seconds to make a decision and I felt quite overwhelmed, doubting if I could do this job. Is this kind of math on daily basis for you?
Or what kind of math do you need as APP?

Sorry for long, boring, confusing post . I hope you know what I mean by overfly/underfly .. I don't know exact English synonyms for words they gave us during an exercise.

ETA: if you have tips for some online sources or books where basic ATC math operations are well explained, I'd be happy to learn about that