Outbound to Inbound Intercept

[Slashmashpotato]

Hi all, would appreciate if you can help on this.

I have encountered numerous debates on the subject pertaining outbound to inbound intercepts. One school of thought believes that the intercept procedure for outbound to inbound is to 'turn the wrong way round', i.e. turning in a longer distance, whereas the other school believes that the way is the same as per all other intercepts, i.e. turning in the shortest and most direct way.

Does anyone know of any website or literature on this issue which I can further look into?


Slash
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[Pilotette]

I have been taught that tracking Outbound to Inbound you need to turn away from the needle (non-command). ie. Dissimilar Intercept.

If, when you say 'turning the wrong way around', you mean turning away from the needle, you are actually turning a shorter distance.

For example: An a/c is tracking OUTBOUND on the 270 radial and wishes to track INBOUND on the 045 track (the 225 radial). The OBS is selected to 045 with a TO indication. Since the CDI is now fully deflected to the RIGHT (non-command), a turn is made to the LEFT onto a heading of 045 + 60 = 105. This is turning the shortest and most direct way.

Not sure if that is what you were asking but I hope it helps :ok: P

[GUARD]

Slash,

I used to teach IFR and my trick was to set the HSI to your inbound. If its ( the head ) is to the LEFT behind you turn RIGHT and vice versa.

Can't lose buddy!

For inbound to outbound just turn to the track and through it BY THE INTERCEPT ANGLE.

As they say in China....Rots of Ruck!

GUARD:ok:

[The Green Goblin]

A HSI will always give you a command indication which can screw you up big time when using primitive instruments like a VOR/ADF

Outbound to inbound take the long way around - can't go wrong:ok:

[Triple Captain]

Outbound to Inbound Longest way round (OIL) helps to put you onto your inbound track. Have a look at the base turn on an NDB approach.

If you were to turn shortest way, it would take more 'effort' to get back on track.

Draw this on paper; it is most noticeable with small angles eg 30 degrees from the reciprocal track.

OIL gives you the direction to turn, once the aircraft is pointed somewhere towards the NDB (60 or 45 degrees) then make corrections to track as an Inbound to Inbound intercept (needles to left then turn left).

[MakeItHappenCaptain]

As a clarification, the OIL concept give the direction of turn to intercept the desired track based the position from where the adf needle is to where you want it to be.
If you are turning from an outbound/inbound track to an outbound track, the shortest direction between the two needle positions is the direction of turn to intercept.
Example outbound on 360, the RB is 180. To track outbound on 030. the RB will be 210, and the shortest distance will be a right turn.
Turning from an inbound/outbound track to an inbound track, the longest direction is the way to go.
Example inbound on 360, RB is 360. To track inbound on 330, R will be 330 and the longest direction between the two is to the right.

Can be fun to get your head around sometimes.

[Back Seat Driver]

SlashMash, here is a neat little website you can try for free to test those schools of thought.

Tim's Air Navigation Simulator (http://www.visi.com/~mim/nav/)

[mattyj]

Just put the little aeroplane on the dotted line...in fact just select Nav on the autopilot and let G1000 do the rest:ok:

[Aerodynamisist]

I always use less is left, rise is right. ie if your out bound (from) 090 on the 270 radial from the station and you want to go in bound (to) 200 on the 200 radial then 200 is less than 270 so go left. if your out bound on the 270 radial and want to go in bound on the 330 then the numbers are rising so go right.

Same method works for inbound to inbound, outbound to outbound, and inbound to outbound. Also works when using numerical gps for track and heading, and if your unlucky enough to fly behind an old barrel type DI.