Lost comms in TAA

[Skyhawk890]

My question has to do with lost communications during an instrument approach in IMC...

Assume you are in a C172 with WAAS GPS system and are en route direct to KLEW at 5000' from the Northwest, in radar contact and speaking with TRACON. You are at 5000' because your flight is short and that altitude is at or above the TRACON's MVA for that area. You are told to expect the RNAV (GPS) RWY 4 approach. You are 35nm NW of the field and before being cleared for the approach, suffer communication failure with ATC.

From the NW, the appropriate IAF is SUMNA. Would ATC expect you to fly direct to SUMNA at 5,000 or climb to 5,800 at or before 30nm NW of SUMNA? When should the turn to SUMNA commence?

 

[MAKG1]

Presuming you're cleared to the airport, fly to the IAF direct, and fly the approach, including its altitude restrictions.

14 CFR 91.85(c)(1)(ii)

What does a TAA have to do with it?

 

[AggieMike88]

First post on PoA! Welcome!

Are you an instrument rated pilot or working on the rating?

Has your instructor introduced the acronym "AVE. F, MEA" to you? It's a way to remember the answer to your question.

 

[Kritchlow]

First post on PoA! Welcome!

Are you an instrument rated pilot or working on the rating?

Has your instructor introduced the acronym "AVE. F, MEA" to you? It's a way to remember the answer to your question.

Holy crap... It would take me longer to remember the acronym than the verbatim rule.

 

[denverpilot]

Holy crap... It would take me longer to remember the acronym than the verbatim rule.

Avenue Q be easier? LOL...

 

[frfly172]

Welcome to the forum.

 

[EdFred]

Has your instructor introduced the acronym "AVE. F, MEA" to you? It's a way to remember the answer to your question.

Never heard it, and I've been flying instrument for over a decade.

To answer the question:
14CFR91.185
(c) IFR conditions. If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following:
(1) Route. (i) By the route assigned in the last ATC clearance received;
(ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
(iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
(iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
(2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:
(i) The altitude or flight level assigned in the last ATC clearance received;

 

[RotorDude]

Never heard it, and I've been flying instrument for over a decade.

To answer the question:
14CFR91.185
(c) IFR conditions. If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following:
(1) Route. (i) By the route assigned in the last ATC clearance received;
(ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
(iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
(iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
(2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:
(i) The altitude or flight level assigned in the last ATC clearance received;

You've left out:

(ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in §91.121(c)) for IFR operations; or

which is the crux of the OP's question, since the TAA shows 5800' as minimum from 30nm until 12nm from SUMNA.
What I would do is climb to 5800' until 12nm from SUMNA, to be sure, then descend to 3100' per the IAP.

 

[EdFred]

You've left out:


which is the crux of the OP's question, since the TAA shows 5800' as minimum from 30nm until 12nm from SUMNA.
What I would do is climb to 5800' until 12nm from SUMNA, to be sure, then descend to 3100' per the IAP.

That's because of the terrain just behind him. They've already cleared him down. I'd stay at 5.

Although, reading his post again, he says he's 35 NW of the FIELD, not the IAF. He's not even in the TAA yet. He needs to be at 6500 or 8600, not 5800. In which case, I climb to 6500 or 8600 depending where.

 

[AggieMike88]

Routing:

Assigned
Vectored
Expected
Filed

Altitude (choose the minimum of the following):

Minimum enroute altitude
Expected
Assigned

And make all the fun you want... AVEF MEA helps me remember the lost comms regulations just fine.

http://scottsasha.com/aviation/handbook/ifrcommfail/avef.html

 

[RotorDude]

Routing:

Assigned
Vectored
Expected
Filed

Altitude (choose the minimum of the following):

Minimum enroute altitude
Expected
Assigned

And make all the fun you want... AVEF MEA helps me remember the lost comms regulations just fine.

http://scottsasha.com/aviation/handbook/ifrcommfail/avef.html

Did you mean maximum?
That's why I don't like over-reliance on acronyms...

 

[RotorDude]

That's because of the terrain just behind him. They've already cleared him down. I'd stay at 5.

That's not what the regs say.

 

[AggieMike88]

Did you mean maximum?
That's why I don't like over-reliance on acronyms...

My mistake. It is maximum. Memory corrected.

 

[EdFred]

That's not what the regs say.

See my updated post, we were both wrong.

 

[RotorDude]

See my updated post, we were both wrong.

From the northwest, the field and SUMNA are at around the same distance, so it would still be around 35nm from SUMNA when the radio failure occurs. Starting a climb to 5800', you'd enter the TAA soon after, so I would not go any higher for the few extra miles.
This is where having color terrain and obstacle mapping in your panel comes in handy.

 

[EdFred]

From the northwest, the field and SUMNA are at around the same distance, so it would still be around 35nm from SUMNA when the radio failure occurs. Starting a climb to 5800', you'd enter the TAA soon after, so I would not go any higher for the few extra miles.
This is where having color terrain and obstacle mapping in your panel comes in handy.

SUMNA is 12+ miles SW of the field. Not sure how 35+12 < 30

35NW of LEW is 41 from SUMNA

 

[aterpster]

Presuming you're cleared to the airport, fly to the IAF direct, and fly the approach, including its altitude restrictions.

14 CFR 91.85(c)(1)(ii)

What does a TAA have to do with it?

You sort of answered your own question. Entering a TAA he is on published routing probably much sooner than on a route-segment IAP.

 

[roncachamp]

My question has to do with lost communications during an instrument approach in IMC...

Assume you are in a C172 with WAAS GPS system and are en route direct to KLEW at 5000' from the Northwest, in radar contact and speaking with TRACON. You are at 5000' because your flight is short and that altitude is at or above the TRACON's MVA for that area. You are told to expect the RNAV (GPS) RWY 4 approach. You are 35nm NW of the field and before being cleared for the approach, suffer communication failure with ATC.

From the NW, the appropriate IAF is SUMNA. Would ATC expect you to fly direct to SUMNA at 5,000 or climb to 5,800 at or before 30nm NW of SUMNA? When should the turn to SUMNA commence?

ATC has no reason to expect you to do any one specific thing so do whatever you feel is in your own best interest. If I were in that position I would turn to SUMNA and begin a climb to 5800' immediately upon determining I was no longer receiving radio communications. I would squawk 7600 briefly and then 7700 briefly to inform ATC I had lost radio communications and was treating it as an emergency. I would then return to the previously assigned beacon code, continue to SUMNA and begin the approach without any consideration of ETAs or holds.

 

[Henning]

Did you mean maximum?
That's why I don't like over-reliance on acronyms...

"Minimum and maximum" is confusing here, shouldn't it be "greatest of"?

If you lose coms, it doesn't really matter if you have glass or not, procedure is the same. If you are given a procedure to follow and that procedure has you at the IAF at 5800', I would cross the IAF at 5800' and fly it exactly as published.

 

[aterpster]

Part of the problem is the nasty habit ATC has of using an MVA that is lower than the segment of an approach on which they plan to have you resume your own navigation. This became quite a topic of discussion after the CFIT at Dillingham, Alaska where the controller cleared him into the TAA at or above 2,000.

Coming from the northwest on a vector at 5,000 the TAA doesn't exist until you cross the 12 mile ring on the left-base sector.

 

[aterpster]

Although, reading his post again, he says he's 35 NW of the FIELD, not the IAF. He's not even in the TAA yet. He needs to be at 6500 or 8600, not 5800. In which case, I climb to 6500 or 8600 depending where.

Where did you get 6500 and 8600 from?

 

[EdFred]

Where did you get 6500 and 8600 from?

Enroute charts.

I plotted out on a map where 35NW of the field would be - which has it outside the MSA on the approach plate (30 from SUMNA). One could be in the quadrangle where the OROCA is 6500 or 8600 depending where exactly you are at.

http://www.iFlightPlanner.com/Aviat...Route=WYLIE-SUMNA-AUBIN-KLEW-4426507N/705341W

WYLIE is about 30NM from SUMNA. But you can see at the end of the route where 35 from the field puts you. And you can see it's outside the 30NM ring on the plate.

Though the 8600 quandrangle would not come into play when I looked at it closer.

 

[AuntPeggy]

ATC has no reason to expect you to do any one specific thing so do whatever you feel is in your own best interest. If I were in that position I would turn to SUMNA and begin a climb to 5800' immediately upon determining I was no longer receiving radio communications. I would squawk 7600 briefly and then 7700 briefly to inform ATC I had lost radio communications and was treating it as an emergency. I would then return to the previously assigned beacon code, continue to SUMNA and begin the approach without any consideration of ETAs or holds.

That sounds quite reasonable. But, I doubt there are FARs or Regs to specify it. Why would you return to your original squawk?

 

[roncachamp]

That sounds quite reasonable. But, I doubt there are FARs or Regs to specify it.

It's authorized by 91.3(b).

Why would you return to your original squawk?

Codes 7500, 7600, and 7700 trigger a very loud, very annoying alarm in many terminal facilities. The message of the codes is delivered in a very short time so staying on them has no benefit to anyone. Getting off of them is beneficial to ATC as it silences the alarm and the discrete code assigned to the flight is better for radar data processing.

 

[N801BH]

It's authorized by 91.3(b).

Codes 7500, 7600, and 7700 trigger a very loud, very annoying alarm in many terminal facilities. The message of the codes is delivered in a very short time so staying on them has no benefit to anyone. Getting off of them is beneficial to ATC as it silences the alarm and the discrete code assigned to the flight is better for radar data processing.

I would have guessed that exact thing happens...

 

[John Collins]

Steven's answer is what would be expected and what I would fly under the circumstances, but is not technically in agreement with the regulations.

(1) Route.
(i) By the route assigned in the last ATC clearance received;
(ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
(iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
(iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
(2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:
(i) The altitude or flight level assigned in the last ATC clearance received;
(ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in Sec. 91.121(c)) for IFR operations; or
(iii) The altitude or flight level ATC has advised may be expected in a further clearance.
(3) Leave clearance limit.
(i) When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect-further-clearance time if one has been received, or if one has not been received, as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
(ii) If the clearance limit is not a fix from which an approach begins, leave the clearance limit at the expect-further-clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of
arrival as calculated from the filed or amended (with ATC) estimated time en route.

Although the pilot has received an expected routing, they are currently on an assigned route to the airport. They are not receiving radar vectors at the time of the radio failure. Therefore, the route according to the regulations is the one last assigned by ATC, that is to the airport.

There is no expected altitude provided. The last assigned altitude is 5000 MSL and must be used except for the portion of the flight that the minimum IFR altitude is above 5000, that is the TAA segment which is 5800 feet. Coming from the NW, 5800 must be used inside the TAA to the airport, as the lower 3100 foot segment is 12 NM from SUMNA and the airport is just past that distance from SUMNA.

The clearance limit is the airport and is not a fix from which the approach may begin (AKA IAF). Although the RNAV RWY 4 approach has been given as the expected approach, a time for the expected further clearance is not provided in the OP's discussion. Since an expected further clearance time has not been provided, the pilot is required to proceed to a fix from which the approach begins. The best choice for the IAF when starting from over the airport is AUBIN as it has a HILPT. Since the pilot would now be on the east side of the airport, 5000 MSL is the higher of the two possible altitudes and the pilot could descend to 5000 MSL. Arriving at AUBIN, an IAF, the aircraft will enter the hold at that location. At that point, they may descend to 3100 feet in the hold. If the pilot needs to delay to lose altitude or to get the time of the approach as close to the ETA or amended ETA, they can use the hold for this purpose. Otherwise they fly the approach.

That is my interpretation of what the regulations require, obtuse as it sounds. I would take Steven's advice and worry about any violation after I got on the ground. The violation would never come IMHO.

 

[AuntPeggy]

It's authorized by 91.3(b).

Codes 7500, 7600, and 7700 trigger a very loud, very annoying alarm in many terminal facilities. The message of the codes is delivered in a very short time so staying on them has no benefit to anyone. Getting off of them is beneficial to ATC as it silences the alarm and the discrete code assigned to the flight is better for radar data processing.

Understood. I mean that swapping through several frequencies is not covered. I agree it makes sense.

 

[AggieMike88]

Codes 7500, 7600, and 7700 trigger a very loud, very annoying alarm in many terminal facilities.

Is the alarm heard by everyone in the facility? Or just the area surround the controller working the flight?

 

[roncachamp]

Is the alarm heard by everyone in the facility? Or just the area surround the controller working the flight?

It uses a dedicated speaker, it's not heard over the speakers or headsets that carry normal radio and facility communications. It's very loud, it will be heard by everyone in the radar room, in adjacent rooms, down the hall, etc., unless something is done to lower the volume. We used to place a copy of the A/FD over the one in the tower as it was in a sloped console. The book would stay in place over the speaker grille resting on the protrusions immediately below. The installation in the radar room didn't permit that.

 

[fiveoboy01]

Curious as to why you would be at 5000 feet when 35 miles northwest of the airport shows the OROCA 6500 feet?

Will ATC descend an aircraft below that altitude in any circumstance?

 

[EdFred]

Curious as to why you would be at 5000 feet when 35 miles northwest of the airport shows the OROCA 6500 feet?

Will ATC descend an aircraft below that altitude in any circumstance?

The MVA is lower than the OROCA, which is why he was cleared down. However, it seems only you and I are the ones that notice that he's not inside the MSA yet based on the position he stated in the OP.

 

[midlifeflyer]

Holy crap... It would take me longer to remember the acronym than the verbatim rule.

Apparently you feel exactly the same way about mnemonics as I do.

SMALS

 

[fiveoboy01]

The MVA is lower than the OROCA, which is why he was cleared down. However, it seems only you and I are the ones that notice that he's not inside the MSA yet based on the position he stated in the OP.

Yeah, farther than the 30nm so I just went by the oroca as it doesn't appear there's an airway leading from the northwest to the IAF.

I guess I don't see it the MVA on the chart. Am I missing it? Or is it intentionally not shown?

 

[EdFred]

Yeah, farther than the 30nm so I just went by the oroca as it doesn't appear there's an airway leading from the northwest to the IAF.

I guess I don't see it the MVA on the chart. Am I missing it? Or is it intentionally not shown?

I did the same thing. MVA's are not shown on enroutes or plates. I'm not even sure if they are published for the public.

 

[roncachamp]

Curious as to why you would be at 5000 feet when 35 miles northwest of the airport shows the OROCA 6500 feet?

Will ATC descend an aircraft below that altitude in any circumstance?

OROCAs cover one degree quadrangles. The terrain/obstacle that's determining the OROCA could be well off the route and above the applicable MIA/MVA.

 

[fiveoboy01]

Understood, so they can and perhaps will descend an aircraft lower at their discretion.

Given that scenario, the controller instructs you to descend to 5000 because you're not near the terrain or obstacle.. however sitting in the cockpit, you may not know that. If comms are lost, is it adviseable to climb to the 5800 foot altitude notated on the TAA outer area while proceeding to the IAF, and then descend to 3100 once within 12NM? Or is it ok to stay at 5000 considering the controller assigned it?

 

[jordane93]

Holy crap... It would take me longer to remember the acronym than the verbatim rule.

This!

 

[EdFred]

Understood, so they can and perhaps will descend an aircraft lower at their discretion.

Given that scenario, the controller instructs you to descend to 5000 because you're not near the terrain or obstacle.. however sitting in the cockpit, you may not know that. If comms are lost, is it adviseable to climb to the 5800 foot altitude notated on the TAA outer area while proceeding to the IAF, and then descend to 3100 once within 12NM? Or is it ok to stay at 5000 considering the controller assigned it?

Not to mention he may be clearing you to 5000, and anticipating giving you another vector before comms go TU. I'm climbing back to 6500 in this scenario.

 

[midlifeflyer]

Understood, so they can and perhaps will descend an aircraft lower at their discretion.

Given that scenario, the controller instructs you to descend to 5000 because you're not near the terrain or obstacle.. however sitting in the cockpit, you may not know that. If comms are lost, is it adviseable to climb to the 5800 foot altitude notated on the TAA outer area while proceeding to the IAF, and then descend to 3100 once within 12NM? Or is it ok to stay at 5000 considering the controller assigned it?

The MVA (minimum vectoring altitude)is a minimum altitude used by controllers who are, well, vectoring you. Or at least have you in the proper sector on radar. Pretty basic IFR stuff done daily just about everywhere there is radar service (maybe less so in completely flat areas with no obstructions)

Once I lose communications, I'm no longer being vectored. While it is probably completely safe to stay at 5,000 to complete the approach, my choice is to head back up to what is now my minimum IFR altitude for that segment of the approach (5800 to SUMNA).

 

[EdFred]

The MVA (minimum vectoring altitude)is a minimum altitude used by controllers who are, well, vectoring you. Or at least have you in the proper sector on radar. Pretty basic IFR stuff done daily just about everywhere there is radar service (maybe less so in completely flat areas with no obstructions)

Once I lose communications, I'm no longer being vectored. While it is probably completely safe to stay at 5,000 to complete the approach, my choice is to head back up to what is now my minimum IFR altitude for that segment of the approach (5800 to SUMNA).

Why 5800? You are outside the 30nm ring. Why is everyone ignoring that part?