Anatomy of a Slam Dunk (and what to do differently in the future)

[0TreeLemur]

Yesterday returning home to TCL from TMB, with numerous thunderstorms in the area, I diverted several times to avoid them.  Wound up on vectors to RNAV04 at TCL.   Loaded and activated the approach in the Avidyne 540.

I'm coming in from the south.  The MSA within 25 nm of the airport is an amazingly high 3700' because of two mega towers 24 miles NNE of the airport.   For some reason the FAA doesn't split the MSA, it's the same for the whole circle.  The VFR chart shows the MSA in the 1-degree tile containing the airport and areas south, west, and directly north as 1,400 ft.

They bring me down to 4,000.   I'm slowed to 90.   Gear down, and 15 degrees of flaps.  I'm not established because they are vectoring me to the final approach coarse outside of the FAF. 

I see the VNAV glideslope indication appear at the top of the scale, and I pass through it.   I contact approach and tell them that I'm above the glide slope.  Meh.  The controller didn't seem to care or understand the implications, just a "Cleared for the approach once established, contact tower, good day."

Once established, I descended at the top of the white arc with full flaps until I popped out of the base at 2400' maybe 2 miles from the end of the runway.    Did not catch the glideslope.   Luckily the bases were high.   If they had been lower, I would have definitely had to go missed.

What should I have done differently?  Some things I can think of:

1) Ask for vector to an IAF to get established earlier.

2)  Ask for a vector that gets me on the final approach coarse quicker?

3) Get my speed brakes fixed so I can really dive and catch the glideslope?  Note, I don't want to do this because it violates the "stabilized approach" rule.

4) File the appropriate form(s) in triplicate to plead with the FAA to divide the MSA circle around the airport.  They could easily have an inner circle or large segment with a lower MSA.

This is the second time that BHM approach has done this to me.   The first time made such an impression that I was on the lookout for it this second time. 

What would you do?

[N201MKTurbo]

I have shoved the rudder to the floor and slipped it. Just have your heading right before the slip, then shove the rudder to the floor and hold that heading. It will come down pretty fast. Also I assume you were at idle power.

[GeeBee]

The times I have been into TCL they did the same thing to me. Complain. Make them bring you around and if the can’t do it right tell them you want your own nav from the IAF. I used to have a Captain that would tell me to call ATC and tell them the airplane is made by Boeing, not Otis elevator.

[MooneyMitch]

38 minutes ago, N201MKTurbo said:

I have shoved the rudder to the floor and slipped it. Just have your heading right before the slip, then shove the rudder to the floor and hold that heading. It will come down pretty fast. Also I assume you were at idle power.

Just asking, as I have no experience doing this, but could a rapid full rudder slip in clouds, possibly contribute to spatial disorientation? 

[ArtVandelay]

I have shoved the rudder to the floor and slipped it. Just have your heading right before the slip, then shove the rudder to the floor and hold that heading. It will come down pretty fast. Also I assume you were at idle power.

Idle power? I thought that’s hard on the engine, because the windmilling at high speed will drive the engine.

[Shadrach]

28 minutes ago, ArtVandelay said:

Idle power? I thought that’s hard on the engine, because the windmilling at high speed will drive the engine.

How is it hard on the engine? Genuinely curious?

[ArtVandelay]

How is it hard on the engine? Genuinely curious?

I don’t know, but I have a placard about low power operation:

[Skates97]

14 minutes ago, ArtVandelay said:

I don’t know, but I have a placard about low power operation:

This one gets debated quite frequently. I subscribe to the school of thought that it is referring to settings in cruise, not a few minutes on descent.

[Shadrach]

11 minutes ago, Skates97 said:

This one gets debated quite frequently. I subscribe to the school of thought that it is referring to settings in cruise, not a few minutes on descent.

Does your C have this placard?

[mhrivnak]

I'd call them on the phone and ask if they generally expect to put you in a position where you can intercept the GP at the FAF, and if not, what are they expecting people to do?

In the air, you could just tell them you need to be at 1800 by the FAF. There's no ambiguity in that, and it still gives them flexibility in how they accomplish it.

[rbp]

3 hours ago, N201MKTurbo said:

I have shoved the rudder to the floor and slipped it. Just have your heading right before the slip, then shove the rudder to the floor and hold that heading. It will come down pretty fast. Also I assume you were at idle power.

in IMC? well done

[Skates97]

43 minutes ago, Shadrach said:

Does your C have this placard?

No, the POH has this:

The 1977 version has this:

[rbp]

my thoughts from an instrument procedures perspective:

if you are being given vectors to final, the vector has to be within a 30 degree angle of the final approach course and must leave you at least 2nm outside the approach gate (which is a point 1nm before the FAF) in low weather. if the weather is at least 500' above the minimums for the approach you've been cleared  and 3nm visibility, then you can be vectored inside the 2nm limit but it still must be before the approach gate. At 4000' and 1nm from the FAF, where the crossing altitude is 1800', you have to lose 2200', which is not possible.

also, for a precision approach, you must intercept the FA course "at an altitude not above the glideslope/glidepath or below the minimum glideslope/glidepath intercept altitude specified on the approach procedure chart." 

nevertheless, if you arrive at the FAF with full deflection of the Glide Path (not glide slope), you cannot legally fly the LPV (409' DA) or the LNAV (608' DA), and you are now on an an LNAV (680' MDA).

my questions:
1. are you equipped for WAAS approaches?
2. which approach did they actually clear you for? 
3. how far outside the FAF did you intercept the final approach course? 
 

 

 

[0TreeLemur]

4 hours ago, N201MKTurbo said:

I have shoved the rudder to the floor and slipped it. Just have your heading right before the slip, then shove the rudder to the floor and hold that heading. It will come down pretty fast. Also I assume you were at idle power.

That's exactly what I did after I broke out of the clouds.   I wouldn't do that in clouds because, well just because.

[0TreeLemur]

2 hours ago, rbp said:

my thoughts from an instrument procedures perspective:

if you are being given vectors to final, the vector has to be within a 30 degree angle of the final approach course and must leave you at least 2nm outside the approach gate (which is a point 1nm before the FAF) in low weather. if the weather is at least 500' above the minimums for the approach you've been cleared  and 3nm visibility, then you can be vectored inside the 2nm limit but it still must be before the approach gate. At 4000' and 1nm from the FAF, where the crossing altitude is 1800', you have to lose 2200', which is not possible.

also, for a precision approach, you must intercept the FA course "at an altitude not above the glideslope/glidepath or below the minimum glideslope/glidepath intercept altitude specified on the approach procedure chart." 

nevertheless, if you arrive at the FAF with full deflection of the Glide Path (not glide slope), you cannot legally fly the LPV (409' DA) or the LNAV (608' DA), and you are now on an an LNAV (680' MDA).

my questions:
1. are you equipped for WAAS approaches?
2. which approach did they actually clear you for? 
3. how far outside the FAF did you intercept the final approach course? 
 

 

 

answers:

Yes: Avidyne IFD-540

RNAV04

Estimate I was about 3 miles outside the FAF, flying an assigned heading of 020.

Having already missed the g.s., hence no vertical guidance I was aware that I flying the LNAV, which was ok with bases at 2400'.  

The whole thing just pi$$es me off because it's inconsiderate because it is counter to the notion of a stabilized approach.  The previous time with ceilings of 500' I had to go missed.

Here's the essence of my question:  With a really high MSA, while being vectored to the final approach course, how do you tell approach to do their job correctly and get you on that course before you pass over the g.s.?

 

Edited March 10, 2023 by 0TreeLemur
corrected MDA to MSA

[rbp]

19 minutes ago, 0TreeLemur said:

Estimate I was about 3 miles outside the FAF, flying an assigned heading of 020.

 

this is in accordance with the regulations, except for the part about needed to be vectored below the glide slope

3nm at 90kts takes 2 minutes, so you would have had to descend at 1100FPM to get from 4,000' to 1,800', which is greater than the recommended 1,000FPM descent rate. 

Not much you could have done on this approach, but next time you can ask them to vector you at least 4nm out from the gate in order to make a stabilized descent from 4,000 to 1800.
 

--------------------

Maximum Acceptable Descent Rates

Operational experience and research have shown that a descent rate of greater than approximately 1,000 fpm is unacceptable during the final stages of an approach (below 1,000 feet AGL). This is due to a human perceptual limitation that is independent of the type of airplane or helicopter. Therefore, the operational practices and techniques must ensure that descent rates greater than 1,000 fpm are not permitted in either the instrument or visual portions of an approach and landing operation.

[MikeOH]

My .02:

I think you are confusing MSA (I don’t think you meant MDA in your last post) with the controller’s MVA (min vector altitude) which I suspect is around 2400 in the vicinity of the IAFs and FAF. The MSA is only for emergencies and the controller is going to be working you based on that sector’s MVA(which you won’t know). I can’t fathom why he had you at 4000, but the MSA didn’t have anything to do with it.

As others have said, you need to make a call and ask, “I got cleared for the RNAV 3 miles from the FAF at 4000 with a 1800 GP intercept altitude. Please explain why that is acceptable!”

[N201MKTurbo]

So, I've done it a couple of times. The first time was on my instrument checkride. The DPE gave me a crossing altitude and I spaced it out. We were about 1 mile from the fix and 1000 feet high when he asked "what was your crossing altitude?" I said something like "aw spit" pulled the throttle to idle and shoved the rudder to the floor. I made the crossing altitude and the DPE said he had never had anybody do that before. Then he said I met the requirement. 

Back then I didn't have speed brakes, so I slipped quite often. It wasn't disorienting at all. But that being said, if you have never done it, do it under the hood with a safety pilot first. If you don't do them, practice visually a few times. I always keep it at the top of the white arc while slipping just to make sure I don't snap roll.

[N201MKTurbo]

31 minutes ago, MikeOH said:

My .02:

I think you are confusing MSA (I don’t think you meant MDA in your last post) with the controller’s MVA (min vector altitude) which I suspect is around 2400 in the vicinity of the IAFs and FAF. The MSA is only for emergencies and the controller is going to be working you based on that sector’s MVA(which you won’t know). I can’t fathom why he had you at 4000, but the MSA didn’t have anything to do with it.

As others have said, you need to make a call and ask, “I got cleared for the RNAV 3 miles from the FAF at 4000 with a 1800 GP intercept altitude. Please explain why that is acceptable!”

I think the proper reply is "Unable". When they ask why, you have to explain that you cannot make that descent rate.

[Ragsf15e]

If it keeps happening, I’d just ask for direct to an IAF or IF (if you’re aligned <90 degrees) and not worry about the controller messing with me.  No need for a vector or anything, just request direct to the iaf.

[0TreeLemur]

18 minutes ago, Ragsf15e said:

If it keeps happening, I’d just ask for direct to an IAF or IF (if you’re aligned <90 degrees) and not worry about the controller messing with me.  No need for a vector or anything, just request direct to the iaf.

This does seem simpler.  Let them worry about getting me to a decent place to start the approach, rather then just on the correct heading.

[0TreeLemur]

1 hour ago, MikeOH said:

My .02:

I think you are confusing MSA (I don’t think you meant MDA in your last post) with the controller’s MVA (min vector altitude) which I suspect is around 2400 in the vicinity of the IAFs and FAF. The MSA is only for emergencies and the controller is going to be working you based on that sector’s MVA(which you won’t know). I can’t fathom why he had you at 4000, but the MSA didn’t have anything to do with it.

As others have said, you need to make a call and ask, “I got cleared for the RNAV 3 miles from the FAF at 4000 with a 1800 GP intercept altitude. Please explain why that is acceptable!”

Good catch.  Didn't mean MDA. 

I really have no idea why they had me at 4000.  You are correct, I don't know what their MVA is.

Who do I call about this?   How do I find the phone number to talk to someone at ABC approach?  Do I really want to do that?   Dealing with bureaucrats is NOT my hobby.  (first time I've used that face on MS).

I'm learning-   I anticipated it happening this time.    Next time I want to talk to the approach controller in a way that produces a better outcome .  Based on what @Ragsf15e wrote, I think I should request a vector to an IAF.   Yesterday, with storms SE of the airport, that would have sent me to IAF ALICE for the RNAV04 at TCL.  Alice was not that far out of my way.   Don't know why they didn't just do that.

I think my lesson here is this:  When the approach controller says vectors to FAF, suggest vectors to an IAF.

 

[rbp]

1 hour ago, 0TreeLemur said:

1 hour ago, Ragsf15e said:

If it keeps happening, I’d just ask for direct to an IAF or IF (if you’re aligned <90 degrees) and not worry about the controller messing with me.  No need for a vector or anything, just request direct to the iaf.

This does seem simpler.  Let them worry about getting me to a decent place to start the approach, rather then just on the correct heading.

you said you were dodging thunderstorms, which I assumed is why you were being vectored on the FA course and not to ALICE or CAPOG

[Ragsf15e]

1 hour ago, 0TreeLemur said:

Good catch.  Didn't mean MDA. 

I really have no idea why they had me at 4000.  You are correct, I don't know what their MVA is.

Who do I call about this?   How do I find the phone number to talk to someone at ABC approach?  Do I really want to do that?   Dealing with bureaucrats is NOT my hobby.  (first time I've used that face on MS).

I'm learning-   I anticipated it happening this time.    Next time I want to talk to the approach controller in a way that produces a better outcome .  Based on what @Ragsf15e wrote, I think I should request a vector to an IAF.   Yesterday, with storms SE of the airport, that would have sent me to IAF ALICE for the RNAV04 at TCL.  Alice was not that far out of my way.   Don't know why they didn't just do that.

I think my lesson here is this:  When the approach controller says vectors to FAF, suggest vectors to an IAF.

 

Just a technique, but If you do decide to go to an IF or IAF, don’t ask for “vectors”.  Just ask for the IF or IAF by name.  Direct is implied, vectors don’t really make sense.  Once cleared to the IAF or IF, You will activate the appoach in your gps and navigate yourself direct.  No vectors required.

When getting vectors to final, you need vectors to get you to the ambiguous place prior to the faf at the correct heading.

[Ragsf15e]

12 minutes ago, rbp said:

you said you were dodging thunderstorms, which I assumed is why you were being vectored on the FA course and not to ALICE or CAPOG

Possibly, but the IF is only 6 miles from the FAF.