Hi all (A:GPS WP DESIRED TRACK,degrees) (A:GPS WP BEARING,degrees) - abs Gives the angle deviation each side of flightplan track direct to the waypoint. This works great till the deviation angle passes through 360 and the bearing numbers increase 360. Is there another way of doing this.

Hi Paul,Try:(A:GPS WP BEARING,degrees) (A:GPS WP DESIRED TRACK,degrees) - d 180 > if{ 360 r - /-/ }Tom

Are you looking to present a course to steer?

Hi Ed It is part of code for 737 NG, LNAV engagement criteria in flight. To be on intercept course 90 degrees or less.

Hello Tom Tried that but it still increases passing through 360 clockwise I tried this:- (A:GPS WP CROSS TRK, nmiles) (A:GPS WP DISTANCE, nmiles) / abs atg rddg It does what I want but is accurate to 30 degrees deviation then only increases to 45 degrees when it should be 90 abeam the waypoint. Don't know if I got the maths bit correct. Paul

Paul,If you want to know whether you are on an intercept course to the flight path, why don't you use GPS WP TRACK ANGLE ERROR combined with GPS WP CROSS TRK distance?Tom

Hello Tom Ah missed that! Got it working now, Maybe too much code but it does not use any bearing numbers. -90 -2 (A:GPS WP TRACK ANGLE ERROR,degrees) (A:GPS WP CROSS TRK, nmiles) (A:GPS WP DISTANCE, nmiles) / tg rddg /-/ s0 - rng & l0 0 < & if{ Thanks again Paul