Magnetic or True North?

[Flying Low]

When a ship gives you BRC do you want it in Magnetic or True north? I’m on a big deck Amphib and the old Air Boss always gave it in Magnetic. He would convert it prior to transmitting. New Boss says it should be in True. I guess I never really thought about it and since I was always land based (H-3’s) I never really spent lots of time in the tower on small ships. What do you guys think?

 

[phrogpilot73]

I've never used True North for anything outside of learning in class that there are three types of north.

 

[C420sailor]

I've never used True North for anything outside of learning in class that there are three types of north.

There are three types of north?

 

[MasterBates]

I always passed magnetic from the CG LSO shack. Some boats would display both, others I had to convert.

Lets put it this way.. Most aircraft don't have a true north gauge (60B would allow it's display though) and will be working in Mag.

 

[eas7888]

There are three types of north?

If I remember my land navigation classes correctly, Magnetic North, True North, and Grid North. I could be wrong.

 

[Pags]

i thought by definition it had to be one way. its been awhile, but i thought brc was mag and foxtrot corpen was true. either way, mag is more useful to aviators.

 

[gotta_fly]

I've never used True North for anything outside of learning in class that there are three types of north.

Aren't the winds on TAFs and METARs given in True North?

 

[phrogpilot73]

Aren't the winds on TAFs and METARs given in True North?

I think they might be, but who really cares about GM angles and the like... It's a FORECAST - and we KNOW how good the weather guessers are with those!

 

[C420sailor]

I think METAR/TAF winds are magnetic and winds aloft are true, but I could be very wrong.

 

[Gatordev]

When a ship gives you BRC do you want it in Magnetic or True north? I’m on a big deck Amphib and the old Air Boss always gave it in Magnetic. He would convert it prior to transmitting. New Boss says it should be in True. I guess I never really thought about it and since I was always land based (H-3’s) I never really spent lots of time in the tower on small ships. What do you guys think?

By definition, "Foxtrot Corpen" is true. By definition, BRC is magnetic and if applicable, corrected for the landing direction (carrier, FLT I DDG, LPD, etc). It's a distinction that gets lost on a lot of people, specifically east coast sailors. Go to places like San Diego or Hawaii where your MagVar is 10+ degrees and it makes a big difference when shooting a TACAN approach to the back of the boat at night.

I believe the actual definitions can be found in the ATP-1 which is the Shoe maneuvering pub.

As for which is supposed to be given, I believe the 80T-122 states BRC. I can't remember for the LHA Natops. For CVs, obviously BRC is required for fixed-wing. I've only had very limited exposure to a CV as a helo and they were constantly turning all the time in Haiti, so you never knew what you would get.

 

[A4sForever]

And to make matters a little more confusing ... magnetic North 'moves' (sometimes daily) and is hard to consistently pin down ... true North, however, is 'true' to it's name and is used on US topographic maps.

We had to deal with these anomalies all the time flying the polar & NOPAC routes.

It's always 'interesting' to see what happens to your nav when you fly 'over the top' ... say from SEA to AMS

 

[wlawr005]

60S has a MAG/TRU button on the flight display that gives you either one whenever you desire. I bet the iPhone has an app for that too

 

[phrogpilot73]

60S has a MAG/TRU button on the flight display that gives you either one whenever you desire. I bet the iPhone has an app for that too

We have something similar in the Phrog, we just have to dig down a few menus to get to it. Hence the desire for MAG and MAG only...

 

[yak52driver]

From U.S. Gov pubs:

Winds aloft: Wind direction is indicated in tens of degrees (two digits) with reference to true north, and wind speed is given in knots (two digits)

TAF and METAR winds are also true north based on NOAA decoding document.

 

[KBayDog]

There's a book out there, I think it's called the LHA/LHD NATOPS MANUAL (NAVAIR 00-80T-106), that defines the BRC as: "base recovery course (BRC). The ship’s magnetic heading during flight operations." (I cut and paste the definition so nothing could be lost in translation.)

Currently on a big deck amphib, and the only thing we're concerned with around the boat is magnetic (BRC) and relative (winds over the deck). In fact, the only time I ask for true winds is when I think the boat's setting me up with a wicked tailwind on final, even though it has good relative winds (usually when they want to maintain a PIM-friendly BRC).