Radar and Step Down Fix

[jayray]

No one on the red board could give me a good answer to this question.

http://www.airnav.com/depart?http://204.108.4.16/d-tpp/0711/05402LD.PDF

The fan marker for the step down fix is not working. Can the tower tell me that I am at the fan marker and then I can descend to fan marker mins? Having a GPS depiction of the marker and the tower call the marker, I feel just as confident that I am at the marker as I would if the marker beacon was flashing. Would the tower have to have precision radar to call it? Where can I find a definitive answer to this question?

 

[KennyFlys]

No one on the red board could give me a good answer to this question.

http://www.airnav.com/depart?http://...11/05402LD.PDF

A bad link... what airport and IAP?

 

[ScottM]

Ken it is the LOC D into SEE, the linked worked for me.


JayRay,

All I can find are the usual substitutes for an ILS. That would be for the outer marker or middle marker being allowed substitution with precision radar as listed in 91.175(k). It seems to me that this FM is really a pseudo MM in the procedure.

 

[poadeleted20]

Can the tower tell me that I am at the fan marker and then I can descend to fan marker mins?

No. If they could, it would say "RADAR" by the words "GRIGG FM" in the profile view. Only fixes with that label may be called by ATC for use in SIAP's when you don't have the requisite equipment on board.

Having a GPS depiction of the marker and the tower call the marker, I feel just as confident that I am at the marker as I would if the marker beacon was flashing.

If you have an IFR GPS with GRIGG in the database you don't need the tower call (see the subtitutions table in AIM Section 1-1-19). Without that IFR GPS, you need a working marker beacon receiver or you can't use the GRIGG mins.

Would the tower have to have precision radar to call it?

Whether they have "precision radar" or not, the fact that the fix is not listed as a radar fix means they are not allowed to call it for you.

Where can I find a definitive answer to this question?

The FAA Instrument Procedures Manual, FAA-H-8261-1A.

 

[jayray]

If you have an IFR GPS with GRIGG in the database you don't need the tower call (see the subtitutions table in AIM Section 1-1-19). Without that IFR GPS, you need a working marker beacon receiver or you can't use the GRIGG mins.

Do you mean 1-2-3 (c)? I see nothing about substitutes in section 1-1-19. And section 1-2-3 says nothing about using an IFR GPS for a marker beacon - only a compass locator.

The FAA Instrument Procedures Manual, FAA-H-8261-1A.

If you could point out the specific section it would be much appreciated - I looked for two hours in the Instrument Procedures Handbook and found nothing specific that would answer my question. Maybe I wasn't looking in the right place.

 

[poadeleted20]

Do you mean 1-2-3 (c)? I see nothing about substitutes in section 1-1-19. And section 1-2-3 says nothing about using an IFR GPS for a marker beacon - only a compass locator.

GRIGG is a fix, not just a fan marker, and Section 1-1-19(e) covers this. If GRIGG is a waypoint in your IFR GPS's database, you're good to go.

If you could point out the specific section it would be much appreciated - I looked for two hours in the Instrument Procedures Handbook and found nothing specific that would answer my question. Maybe I wasn't looking in the right place.

See page 5-15, lower right, last paragraph. And for an example of where ATC radar is an option to identify a fix, see the NASZR and HURTZ intersections on the BWI ILS 28 approach. On that approach, you have three ways to ID those fixes -- DME, GPS, and ATC radar. Absent the word RADAR by the fix name, ATC can't call it for you.

 

[TMetzinger]

As Ron said, if the fan marker has a five-letter ID associated with it, it's a colocated fix, and should be in your GPS database.

 

[kkoran]

See page 5-15, lower right, last paragraph.

Ron,

I don't believe this paragraph is relevant to the situation on the KSEE approach because it's talking about situations where radar is required (the procedure can't be flown without it) vs. the KSEE situation where the procedure can be flown without radar.

I agree that the fix must be annotated "RADAR", like in your KBWI example, in order for the controller to call it.

 

[ghogue]

No. If they could, it would say "RADAR" by the words "GRIGG FM" in the profile view. Only fixes with that label may be called by ATC for use in SIAP's when you don't have the requisite equipment on board.

If you have an IFR GPS with GRIGG in the database you don't need the tower call (see the subtitutions table in AIM Section 1-1-19). Without that IFR GPS, you need a working marker beacon receiver or you can't use the GRIGG mins.

Whether they have "precision radar" or not, the fact that the fix is not listed as a radar fix means they are not allowed to call it for you.

Ron,

According to AIM, ATC may be able to identify a fix that's not labeled "RADAR", however, the pilot should not necessarily rely on this.

AIM 5-4-7. Instrument Approach Procedures

g. Pilots should not rely on radar to identify a fix unless the fix is indicated as “RADAR” on the IAP. Pilots may request radar identification of an OM, but the controller may not be able to provide the service due either to workload or not having the fix on the video map.

 

[Dwight B. Van Zanen]

Ron,

According to AIM, ATC may be able to identify a fix that's not labeled "RADAR", however, the pilot should not necessarily rely on this.

AIM 5-4-7. Instrument Approach Procedures

g. Pilots should not rely on radar to identify a fix unless the fix is indicated as “RADAR” on the IAP. Pilots may request radar identification of an OM, but the controller may not be able to provide the service due either to workload or not having the fix on the video map.

My only real experience with this issue was at PAE, the ILS 16R approach. The LOM is not marked RADAR on the plate. See this:

http://204.108.4.16/d-tpp/0711/00142IL16R.PDF

With the LOM out of service, I was told they could not authorize the ILS 16R approach, even though they have radar and they know where it is and I could intercept the glide slope.

 

[TMetzinger]

Is this one of the cases where IFR GPS can't substitute for ADF, or could someone identify RITTS with IFR GPS and fly the approach?

Even if that would be legal, good luck getting ATC to issue the approach clearance.

 

[poadeleted20]

Is this one of the cases where IFR GPS can't substitute for ADF, or could someone identify RITTS with IFR GPS and fly the approach?

Not according to AFS-410, assuming the validity of a parallel with them saying you could use GPS to sub for DME on a VOR/DME approach (locating a fix, not flying an arc) when the DME is OTS.

Even if that would be legal, good luck getting ATC to issue the approach clearance.

Agreed. You'd probably have to get ATC-410 to call the Regional ATC office to get them to call the involved facility. Even if your cell phone works in the air, that ain't all gonna happen until long after you run out of gas.

 

[poadeleted20]

Ron,

According to AIM, ATC may be able to identify a fix that's not labeled "RADAR", however, the pilot should not necessarily rely on this.

AIM 5-4-7. Instrument Approach Procedures

g. Pilots should not rely on radar to identify a fix unless the fix is indicated as “RADAR” on the IAP. Pilots may request radar identification of an OM, but the controller may not be able to provide the service due either to workload or not having the fix on the video map.

That says "outer marker." This is a step-down fix well inside the FAF, and I'm not sure that translates.

 

[ghogue]

That says "outer marker." This is a step-down fix well inside the FAF, and I'm not sure that translates.

Ron,
My response was not so much to this particular fix "GRIGG", but more to your statement "Only fixes with that label may be called by ATC for use in SIAP's when you don't have the requisite equipment on board."

Was concerned that someone might believe that applied to all fixes.

gary

 

[gismo]

There's a NOTAM in effect that specifically states that the GRIGG mins are NA. I'm pretty sure that means you can't use the step down altitude regardless of how you identify the fix.