OCTA Traffic 1:60 rule?
 

Hi Everyone,

I have heard Pilot's on the radio seperating themselves from traffic OCTA by asking for bearing and distance information from an navigation aid on this occasion it was an NDB. I was wondering whether they would be using the 1:60 rule to do this (as a back up to TCAS, when there in no radar etc), however I am having trouble working through the example below.

Aircraft A inbound on the 360 bearing TO the station at 60nm.
Aircraft B outbound on the 170 bearing FROM the station at 40nm.

What would be the easiest way to calculate the lateral seperation between aircraft A and B using the 1:60 rule.

Also is this kind of calculation used by many of you in the airlines for the purpose of traffic seperation.

Thanks c152g

it's a hiddous thing the 1 in 60...and it wont help u when u are flying from Birdsville to Alice Springs..

u need to be able to pinpoint your position on the map and work out a heading correction...any instructor (worth flying with) will do it easy..

I have heard Pilot's on the radio seperating themselves from traffic OCTA by asking for bearing and distance information from an navigation aid on this occasion it was an NDB.

Unlikely - an NDB will not give you a distance. Most probably they were using the FMC position on a fix at the NDB. An NDB in any case is very inaccurate for bearing info

Aircraft A inbound on the 360 bearing TO the station at 60nm.
Aircraft B outbound on the 170 bearing FROM the station at 40nm.

The datum is the 180 radial from the beacon- yes? Thus a/c A has zero displacement from that datum. For a/c B, the "1 in 60" rule means that 10 degrees displacement at 60nm is 10 miles sideways. At zero miles it is zero. Simple mental says thus at 40nm it is 6.6nm. - yes?

What would be the easiest way to calculate the lateral seperation between aircraft A and B using the 1:60 rule.

Only assuming that both a/c hold their tracks as they are, and assuming they are equal speed they will pass at 50 nm from the fix - yes? Thus at the point of passing they are still 10 degrees apart but at 50 miles from the fix, so 5/6 x 10 = 7 and a bit NM apart -yes?

Also is this kind of calculation used by many of you in the airlines for the purpose of traffic seperation.

No. Separation in the GFA is based on time at a beacon with any conflicting traffic separated by 10 minutes at the same fix..

My brain hurts.