Base vs. Procedure Turn

[the_bookkeeper]

What is the difference between them? Is it just the name?
Thanks

[eckhard]

A base turn is one where you leave a beacon on a particular bearing and then turn to establish inbound on a different bearing. In other words, the two bearings are not reciprocal.

In a procedure turn, you establish inbound on the same bearing from the beacon as the one that you tracked outbound. The two bearings are reciprocal.

Easier to understand if you look at some examples.

Here is a base turn:

http://www.nats-uk.ead-it.com/aip/current/ad/EGTC/EG_AD_2_EGTC_8-1_en.pdf

And here is a procedure turn:

http://www.nats-uk.ead-it.com/aip/current/ad/EGJB/EG_AD_2_EGJB_8-1_en.pdf

I hope these make the difference clear.

Regards,

Eckhard

[Superpilot]

Good explanation above. Just to add a bit more:

A procedure turn is one that is made with either of the following:

1.) A turn first of 45 degrees left/right and then another turn of 180 degrees opposite in direction to the initial one. Or with:

2.) A turn first of 80 degrees left/right followed by one off 260 degrees in the opposite direction.

The base turn is made by first of all proceeding outbound on a certain track/bearing from a fix for a set time or distance (depending on the category of the airplane) and then by making a turn in order to position the aircraft on a final approach track/course.

[blueplume]

Good explanations but keep it simple.

A Procedure Turn is one you make when you fly a published procedure.

A Base Turn is one you make generally when told to by ATC when under Radar Control. ATC will usually tell you turn onto a heading which will put you in a good position to intercept the inbound course or when they haven't yet cleared you for a Visual Approach for whatever reason they want.

Just like visual circuit really.

[eckhard]

Hmmm......

Not sure I agree completely with blueplume.

I see what you are saying, but I had the impression that the_bookkeeper was asking about a more technical description to resolve some confusion that he may have had.

A 'base turn' may be part of a published procedure, as in my first link. However, it is true that some ATC units and pilots refer to a generic 'procedure turn' to cover both types. Still, a bit like the use of the generic term 'height' when we really mean 'altitude', it doesn't really matter as long as everyone knows what they (and the other fellow) are doing and thinking!

[411A]

A 'base turn' may be part of a published procedure...

Indeed so, quite common in some areas....not in others.