IFR Question

[TopperHarley]

Hey guys,

Here's a scenario:

You're doing an VOR/DME approach. Assume you have passed the FAF and have started your timer for the missed appraoch point. Also, assume the MAP is identified by timing only, and does not rely on your DME. Now, as you pass the FAF, your DME fails. Legally, can you still continue the approach?

I would think you can, since you are inbound from the FAF, and you don't need your DME to identify/navigate to your MAP; however, according to a question in the aerocourse workbook, you must abandon the approach regardless. Do you agree with this? Is there any reference in the CARs which allows you to continue the approach under such circumstances, or, must you always abandon it?

Thanks in advance.

[Stinky]

Odds are, if the MAP is identified by timing as opposed to a DME distance, it's because the DME is not reliable, ie. an off airport VOR, you are too low to get DME.

In many cases, you are very likely to lose the DME past the FAF, thus the use of timing.

[heeypilot]

you would need your DME if you go in the missed approach. i'm too lazy to look in teh cars

[chief]

If I had to abandon an approach every time i lost a dme signal...........

[talkinghead]

If you are doing a flight test/ppc ride you need THE DME working.

[talkinghead]

OMG that took a bottle of beer to locate the reference . I can only find it in the INSTRUMENT PROCEDURES MANUAL (so far), Pg 4-52.

[confuzed]

Someone can correct me if I'm wrong, but if the approach says on it VOR/DME you need BOTH of those working in order to conduct the approach. If one of them fails, you no longer have the required equipment to fly that particular approach so a missed approach is mandatory. If it said VOR/DME or VOR, then you're good to continue the approach. However, that being said check your minimums as they will most likely be a little higher then the VOR/DME minimums would be.

[Stinky]

If the DME failed inside the FAF and the MAP is identified with timing, why would you fly the missed? You no longer need DME.

If the missed approach procedure required DME, most VOR/DME approaches don't though. But if it does, just advise ATC that you will be unable to fly the published missed because your DME has faile, but you are able to continue the approach.

Of coarse if the MAP is identified only by DME, then you must miss.

[bush pilot]

Confuzed I would say you are correct, I just took a quick look through the Cap 4 and did not see one appch that had timing with a DME (unless I missed it) and if it did have Timing then Stinky I think your on the ball with that one, however if you are not in a radar invironment where you can get missed approach clearence other than published then you should abort.

All that said if you have a GPS(non IFR) that gives a read out of distance from said DME sight then that should safice(unless your on a PPC or check ride).

[55+]

Someone can correct me if I'm wrong, but if the approach says on it VOR/DME you need BOTH of those working in order to conduct the approach. If one of them fails, you no longer have the required equipment to fly that particular approach so a missed approach is mandatory. If it said VOR/DME or VOR, then you're good to continue the approach. However, that being said check your minimums as they will most likely be a little higher then the VOR/DME minimums would be.

Hey confuzed, you are not confuzed, you are indeed correct. If the approach procedure is identified as VOR/DME then DME is required for the procedure as that is the only way(conventional) to identify the FAF, also the remainder of your statement is also true on VOR/DME or VOR. There is a way out as you are aware if your DME fails or is U/S and you have your trusty KLN-90B/C/D or whatever as the procedures are overlayed you can identy the FAF . Of course you have to load up the procedure in your trusty KLN-90 whatever or your Garmin whatever.....

Best
55+

[Pratt]

I agree with confused and 55+.

[grounded]

Yup, if the DME is listed on the approach plate, it is required. In reality however, the GPS will give you a distance from the FAF of MAP just fine. You could be asking for trouble if you continue an approach when something like that fails and there is FSS or a tower on the field, obviously.

[55+]

Yup, if the DME is listed on the approach plate, it is required. In reality however, the GPS will give you a distance from the FAF of MAP just fine. You could be asking for trouble if you continue an approach when something like that fails and there is FSS or a tower on the field, obviously.

.... but the FAF will be identified because all FAFs are required to have a 5 letter ICAO ident as well as coordinates and the DME distance from the source. If you have the capability of loading up the approach from a certified RNAV(GNSS) reciever or an FMS you can fly the VOR/DME procedure to the published minima if the DME source is not avialable. Also timing blocks are not published on a VOR/DME because the MAP is DME referenced.

[grounded]

Someday, maybe the company I work for will get us GPS approach certifed, until then we can just use it to go enroute direct. It would be nice to have that option as well though.

[turbo-prop]

The only reason you would have timing on a VOR/DME approach plate is if there is another approach on the plate like a VOR approach or a LOC approach that doesn't use reference to the DME.

[Schlem]

I agree with Pratt, Confuzed, and 55+.

[Stinky]

The only reason you would have timing on a VOR/DME approach plate is if there is another approach on the plate like a VOR approach or a LOC approach that doesn't use reference to the DME.

Have a look at Barrie/Orrilia VOR/DME A approach. The IF and FAF are identified with a DME distance. Timing is used for the MAP. This is because the VOR is not at the airport and inside the FAF the DME is not reliable.
In this case if your DME equipment failed inside the FAF you would not need to abandon the approach since you no longer require the DME. I would advise ATC if the missed approach required the use of DME, so they can give you an alternative missed approach, in this case it does not.

[Mitch Cronin]

You pass the exam for asking the flipping question the rest of the gang can't agree on an answer to!

Everyone else should stop the guessing and wait until one who is certain of the answer, and is in a position to be confident that his/her certainty is backed by sound credentials, answers the question for the rest of you.

Answer?:

[55+]

"Have a look at Barrie/Orrilia VOR/DME A approach. The IF and FAF are identified with a DME distance. Timing is used for the MAP. This is because the VOR is not at the airport and inside the FAF the DME is not reliable.
In this case if your DME equipment failed inside the FAF you would not need to abandon the approach since you no longer require the DME. I would advise ATC if the missed approach required the use of DME, so they can give you an alternative missed approach, in this case it does not."

Fraid not. Look at Kenora VOR/DME A, that is the correct design as stipulated in Chapter 5 Section 2 Tacan and VOR/DME TP-308 Criteria for the Development of Instrument Approach Procedures. As you can see the MAP is a DME fix(required) and the FAF has a 5 letter ICAO ident and coordinates(DMM) also note no timing block. From/To a facility(VOR/VORTAC) makes no difference and the notion DME is unreliable inside an FAF/SDF is sheer nonsense, if such was the case that would have been picked up during the flight check and not signed off.

I suspect the Barrie procedure will be up for revision and ammended as such in due course

[Stinky]

55+, you obviously know a lot about approach design, I do not.

I do feel fairly confident that if I were on a ride and were given the Barrie approach and the examiner failed the DME on me inside the FAF, I would not be faulted for continuing the approach.

It's funny how such a seemingly simple IFR question leads to such a debate.

[YVR Dude]

If you didn't need the DME it would be a VOR approach...but a VOR/DME requires both. Inside the FAF with the loss of the DME maybe minimums are higher, you don't know...better to execute a miss, review the charts for a VOR approach and continue again. The approaches are designed with safety in mind, so always err on the side of safety...whether you are doing a ride or not...don't mess around!

my two cents...

[Stinky]

YVR Dude

The approach I was referring to is a VOR/DME approach that uses timing because the VOR is some 10 miles off of the airport and you lose the DME inside the FAF. In this case you do not need DME inside the FAF. There is no VOR only approach published.

[confuzed]

YVR Dude

The approach I was referring to is a VOR/DME approach that uses timing because the VOR is some 10 miles off of the airport and you lose the DME inside the FAF. In this case you do not need DME inside the FAF. There is no VOR only approach published.

Well I'm not too sure what anyone who is agreeing with me so far thinks about this matter but here we go. In this case, I'd deem the approach unsuitable and unuseable. I'd alert navcanada to this, so they are in the loop and can go to check it out themselves. If the plate says VOR/DME, then that's the equipment REQUIRED for that particular approach....does it say next to VOR/DME (DME signal will be lost inside the FAF so use timing)? I'm guessing not, so back to my original point. If you lose it, you go missed....simple as that. Either find a different approach to get in, or go back home and call navcanada and ask them what's going on with that approach. Things break from time to time, maybe there's something wrong with the equipment on the ground. You know what though, who knows.....for some odd reason maybe that's the way they designed this approach. I'd have to look at it, and I don't have any CAP 4's kicking around anymore. I'm somewhat doubtful though, unless they worded the approach wrong...but generally, however the approach is laid out VOR/DME or VOR or NDB, etc...this is the REQUIRED equipment for all segments of that approach. You don't pick and choose when you can have or use certain equipment.

I'm not trying to sound harsh, but dude seriously. Approaches are designed for a specific reason, and have to be followed according to the way they are outlined in the CAP. If you start making up your own approaches, or not following the ones that are in the CAP you're just inviting something to happen.

[Hedley]

If you lose it, you go missed

Must be nice to live in such a black & white world. There's an approach not too far from here, and all the locals know that you lose the DME as you descend past the FAF, because of the distance to the VOR/DME.

Every airplane does it. There's nothing wrong with all the airplanes and all the DME's around here. There's nothing wrong with the VOR/DME, either - it's because of the distance to the VOR/DME, which is not co-located with the airport.

I'm sure NavCan knows about it, and doesn't care. They probably figure everyone has GPS.

[confuzed]

If you lose it, you go missed

Every airplane does it. There's nothing wrong with all the airplanes and all the DME's around here. There's nothing wrong with the VOR/DME, either - it's because of the distance to the VOR/DME, which is not co-located with the airport.

So what you're saying is follow the herd and do it anyway? Wow....that's bold. Since when is safety not black and white? I can think outside the box there Hed, don't you worry. However, when it comes to safety and flying an aircraft down to say 300-400 feet off of the ground I tend to follow proven procedures that have been implemented in the name of safety. If Navcanada knows about it, and aren't doing anything about it well that's another debate right there now isn't it? Yes I know back in the day there wasn't this and wasn't that and all that nostalgia, but we've come a long way since then haven't we?

A question was asked and a question was answered. Someone asked do you need the equipment to work, and I said that whatever the approach says is required. If the approach is not useable, then find a different approach. If one doesn't exist, well then sit down, have a cup of coffee and relax. There's nothing you can do about the weather, if you don't get in today then maybe you'll get in tomorrow.