Do you have to be within 5 degrees when desending outbound?

[lemon_torte]

Hi there!

I have to fly a lot of procedural appraoches in and around scotland. I always aim to be within 5 degrees before descending outbound but sometimes I get funny looks from the left hand seat when I do this!

I normally get the "you only have to be within 5 degrees when descending inbound" speech but this doesn't make sense to me as surely you're following a proscribed track across the ground so if you're not following that track, how do you actually know where you are with regards to terrain?

I have asked several well experienced captains if they know the answer and I get a different answer every time! I have also looked in the Flight Information Suppliment that we keep onboard but no joy, so I figure Id ask the all knowing, all seeing wonderful ATC controllers that look after me when I attempt to aviate!

So please if you know the answer please put me out of my misery!

Thanks a lot!

LT

[bookworm]

I'm sure you'll get some good input from ATC here, but the procedure designers tend to hang out on Tech Log.

http://www.pprune.org/forums/showthread.php?t=113720

should be a start.

[TopBunk]

LT

I would suggest that if the procedure starts overhead and you perform any procedure to a platform altitude, then you are safe to descend to the prescribed altitude when transitting the overhead, even outside the 5 deg. limit. After all, you will descend below that platform altitude in the opposite direction!

AFAIK the 5 deg tolerance is for the inbound track for obstacle clearance reasons, outbound is no issue!

Waiting to be proven wrong .....

[nimston]

Your quite correct topbunk, The Old Bean should have asked me I could have told her, Try asking one of the new captains hahaha,

Regards

[ADIS5000]

I don't claim to be an expert on this but, as the procedure will be designed to give both terrain clearance and to keep you inside controlled airspace (if appropriate) then the outbound track is surely as relevant as the inbound track? This is especially so if you fly a Cat C or greater aircraft where the procedure will be by definition larger. Whether or not the 5 degree tolerance is specified anywhere (AIP?) for the outbound track I don't know, but it sounds to me like your adherance to 5 degrees outbound would be considered best practice?

Regards, ADIS

[Alteburger]

PANS-OPS may have the answer you are looking for.

[KiloKilo]

...descending outbound...

Sorry, just had a funny sound to it. ;)

[Capt Wally]

Like all approaches the whole idea of any approach is to get visual (obviously) in the first place so any deviation from the surveyed tracks of an approach increases the chance of becoming a statistic revolving around those ugly letters "CFIT" (Controlled Flight Into Terrain).
Outbound interception. As long as one is actually heading in a direction to intercept the outbound track (assuming they are off it in the first place) then this is accepted as being suitable for safe flight in Oz. The different categories as in A&B/C&D & in some cases E cat's different outbound tracks attest to the fact that the need to be within 5 degs of any outbound track is essentially not required because often the difference of say Cat B to Cat C track exceedes 5 deg's in the first place.
So anyway you look at it fly accurately as possible & there should be little need to ponder this as one is in cloud, at night & juggling the torque guages to match the correct speeds...............now where would we be without LRN (GPS) these days? :-)

.....there's a great saying......applies to most things in life esspecially aviation........"chance favours the prepared mind"............simply be prepared !:-)


Capt wally :-)

[DB6]

There is no outbound tolerance given in PANS-OPS, it merely says 'fly outbound on the specified track'. Descent outbound is to a safe platform altitude and a quick inspection of many procedures will show different tracks for different aircraft categories, all safe down to the platform altitude (Inverness is a good example). Indeed depending on wind conditions (e.g. strong tailwind outbound) you may put yourself in an impossible position if you delay descent until within 5 degrees, not to mention making the monitoring pilot's job that much harder. Tolerances inbound are much tighter since the obstacle clearance is much lower, hence the 1/2-scale / 5 degree requirement before descent. If you work for Loganair get hold of me at work for more :8 .

[tori chelli]

When I worked at an airfield with a lot of CPL-IR training going on, it was taught that you off-set double or even triple the drift on the outbound leg to allow for the effect of (typically) a crosswind enlarging or tightening your base/procedure turn from the outbound leg to the inbound.
Therefore it's almost inevitable that your outbound track will be different from the outbound QDR, but the terrain clearance built into the design of the holding AREA (as distinct from the holding pattern) for the procedure should take care of allowances made for typical winds experienced at the location.
Being lined-up on the inbound leg is the thing...otherwise you're not where you should be at DA/MAPt :} :}
Tori

[lemon_torte]

Thanks chaps! :ok:

DB6, Nimston I will endeavour to come find you with my aviation ponderings in the future! (DB6 that was the answer I was looking for! Cheers!)

LT