IFR approach question

shwaman · Post by **shwaman** » Mon Feb 21, 2005 11:27 am

Hello....had a question...thought I was clear on this but recently had some confusion thrown in by some conversation with people...

Say an aircraft is on approach to Timmins, coming from the south to do an ILS 03, aircraft is cleared for the approach and told to switch over to radio...now the aircraft is not GPS equipped....say the aircraft is 30-40 dme back, is it legal to alter heading, while maintaining min safe alt, to intercept the localzer inbound for the straight in? or is it necessary to do the arc transition?

It was my understanding that unless specifically given an intercept heading by center, and cleared to intercept the loc, you had to do the arc transition....any thoughts?

CAL · Post by **CAL** » Mon Feb 21, 2005 11:44 am

I was under the impression that once cleared for the approach you are good down to sector at PD. But what did the controller specifically clear you for?....the ILS via the arc transition? or straight in or?....I am bit unsure myself but would never elect to do the arc unless told to do so....

shwaman · Post by **shwaman** » Mon Feb 21, 2005 11:52 am

I agree, arcs are not my favourite! the clearance was just "cleared for ILS 03" no specifications....

groundtoflightdeck · Post by **groundtoflightdeck** » Mon Feb 21, 2005 11:58 am

You can do "self-vectors" if you are cleared for it, but I don't know if that could be done in Timmins due to Radar limitations. You would likely be "cleared to Timmins for and approach"- which would clear you for the procedure, probably arch or strait-in if you are RNAV equipped. Bottom line, if you have no RNAV, do you really want to be pointing to the NE and hoping you intercept somewhere suitable for an approach? If the wind was way off you could be blown to a funny spot on the approach, maybe even by the approach entirely. So I would doubt its legal unless you are on radar and have been authorized to do self-vectors.

TopperHarley · Post by **TopperHarley** » Mon Feb 21, 2005 12:17 pm

RAC 9.3 (Approach Clearance) indicates that if you are "cleared for an approach," you can proceed via a routing of your choice; however, you are responsible for maintaining a suitable min altitude (MSA, safe 100, or AMA), complying with noise abatement procedures and remaining clear of class F airspace.

shwaman · Post by **shwaman** » Mon Feb 21, 2005 12:51 pm

ya, I read that in RAC section too, the wording wasn't quite like that:

"pilots who choose to proceed to the instrument procedure fix via a route that is off an airway, air route , or transition are responsible for maintaining the appropriate obstacle clearance, complying......"

Which I interpretted as going direct to the IF, via RNAV.......however I guess this could be interpretted as cutting over to intercept the localizer, then tracking that inbound to the fix, agreed? but I also see the point that the safest way without GPS is the arc, due to unknown factors such as wind drift......

TopperHarley · Post by **TopperHarley** » Mon Feb 21, 2005 1:11 pm

If there is noone that can give you radar vectors anymore to the final approach path (i.e. vectors for an intercept heading), then I do believe if you are cleared for the approach (in this case, the Timmins ILS 03), you have a few options:

1. Proceed direct to ZTS (the FAF), and complete a procedure turn (i.e. do the full approach);
2. Do a DME arc to transition to the final approach course and intercept the ILS.

Someone please correct me if I'm wrong, as it's my understanding that you cannot self-vector yourself to intercept the ILS (i.e. you can't select a localizer intercept heading on your own).

Capt · Post by **Capt** » Mon Feb 21, 2005 1:18 pm

Not for-sure, but I do not think you can choose your own headings to intercept. when cleared for an approach you must follow the procedure (arc, or RNAV, or full procedure etc.). if atc gives you vectors you can do the staight in, or if you have RNAV, but you can NOT pick headings of your choice to IF.

zzjayca · Post by **zzjayca** » Mon Feb 21, 2005 2:15 pm

If ATC gives you a clearance for a specific approach eg. "CFABC cleared to the Timmins airport for an ILS03 approach", than this is the approach you must fly as published.

If ATC gives you a clearance for a non-specific approach eg. "CFABC cleared to the Timmins airport for an approach", than you may fly any published approach procedure.

If there is no published straight in approach, in either case, than you have to request a straight in approach approval from ATC before performing one. In this case, if approval is given, you are responsible for terrain clearance once you descend below minimum safe altitudes.

Normally, for a straight in approach, ATC will specify this in the clearance. EG. "CFABC cleared to the Timmins airport for a straight in ILS03 approach", or "CFABC cleared to the Timmins airport for a straight in ILS03 approach via the 14 DME arc."

Rem · Post by **Rem** » Mon Feb 21, 2005 3:19 pm

You can request and be cleared to "intercept the localizer outside the IF and track it inbound for the ILS 03" or words to that effect. I've done this a few times going into YTS. For altitudes, simply descend to MSA (inside 25nm) until you cross the IF on the localizer. If you're coming from the south this involves a 20 degree left turn about 25-30 miles back. When you cross the IF you can descend further to the next published altitude and follow the glidepath down from there, it's quite simple. The key is that you can fly around at MSA all you want within 25nm as long as ATC approves the manoeuvre, which they did with the clearance I described above.

I'd only do this if you're coming from a direction that pretty much puts you "straight in" anyway. If you have to do a lot of manoeuvering to intercept the localizer you're better off just doing the arc or a full procedure. Also you'd probably only want to do that if you have the nav equipment that would allow you to confirm you're intercepting the localizer outside the IF.

planett · Post by **planett** » Mon Feb 21, 2005 5:16 pm

All the equipment you need to intercept a localizer here is an ADF and DME. Forgive me if my Timmins plate is out of date, but mine shows a beacon, a DME source, a localizer and "No PT".

Now Read RAC 9.15 and RAC 9.16. It will explain that "No PT" allows aircraft to self navigate without performing a PT, and the arc is a nice way to do this. The arc is also unnecessary unless you try to fly arc altitudes which are often lower than sector. Your bearing from the beacon, and distance information is enough to determine exactly where you are and how to intercept the loc from where you are.

Using 3 degrees final slope you should intercept GP at 6-7 miles out, (at 2000 AGL) so try to intercept the loc at about 8-9 miles by steering a 30 degree intercept when you are 10 degrees from track by the beacon bearing around 10 miles out. Works everywhere, every time.

Coming from the north, just do the PT.

Cap'n P8 · Post by **Cap'n P8** » Mon Feb 21, 2005 7:10 pm

I asked this question just after the site was hacked, specifically, could you use RNAV to position yourself on the approach without doing the full procedure. It's nice to see someone finally pulled the CAR's references I was looking for!

PS I surprised Capt. SnJ hasn't made any stupid posts about dead babies and the like!

PA31 Driver · Post by **PA31 Driver** » Tue Feb 22, 2005 10:27 am

If you can align yourself for the straight in approach before the FAF with the equipment on board and have confirmed the wind & speed & runway conditions then " Yes you can " because of the no P/T.