# Weird RNP approach procedure

#### LV-ARG

##### Well-Known Member
Just wondering, what do you think about the end part of this approach procedure?

I've never seen such a sharp turn at the FAF leading to a descent down to minimums.

From what I recall, the initial and intermediate phases of an approach are there to set you up on course such that in the final phase, all that there is left is descending.

Have you ever seen something like this somewhere else? I know that there are RNP AR approaches with RF turns down to very low altitudes, but this is a conventional RNP approach.

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#### Roger Roger

##### Paid to sleep, fly for fun
Just wondering, what do you think about the end part of this approach procedure?

I've never seen such a sharp turn at the FAF leading to a descent down to minimums.

From what I recall, the initial and intermediate phases of an approach are there to set you up on course such that in the final phase, all that there is left is descending.

Have you ever seen something like this somewhere else? I know that there are RNP AR approaches with RF turns down to very low altitudes, but this is a conventional RNP approach.
I don’t see what’s weird about turning a 5 mile final?

#### LV-ARG

##### Well-Known Member
That there is almost a 90° turn on which you are supposed to be descending. Every other approach I've flown usually has a straight course leading to the FAF, not a turn.

Its perfecly ok to fly something like this VFR, but IMC? little bit weird if you ask me.

Most airlines require you to be fully stabilized by 1000ft agl in order to continue an approach when IMC. In this case, you are probably completing the turn at about 4nm and 1100ft agl which is quite close.

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#### CFIT99

##### I'm probably commenting ironically...
That there is almost a 90° turn on which you are supposed to be descending. Every other approach I've flown usually has a straight course leading to the FAF, not a turn.

Its perfecly ok to fly something like this VFR, but IMC? little bit weird if you ask me.

Most airlines require you to be fully stabilized by 1000ft agl in order to continue an approach when IMC. In this case, you are probably completing the turn at about 4nm and 1200ft agl.
it's an RNP approach, the FMS will do a smart turn, you will turn and descend for that point

#### Roger Roger

##### Paid to sleep, fly for fun
Its perfecly ok to fly something like this VFR, but IMC? little bit weird if you ask me.
the airplane don’t know the difference, especially with the AP on.

#### gotWXdagain

##### Polished Member
That there is almost a 90° turn on which you are supposed to be descending. Every other approach I've flown usually has a straight course leading to the FAF, not a turn.

Its perfecly ok to fly something like this VFR, but IMC? little bit weird if you ask me.

Most airlines require you to be fully stabilized by 1000ft agl in order to continue an approach when IMC. In this case, you are probably completing the turn at about 4nm and 1100ft agl which is quite close.

Probably don’t pull up the RNP’s into MSO

#### LV-ARG

##### Well-Known Member
it's an RNP approach, the FMS will do a smart turn, you will turn and descend for that point

Last time I flew something similarly coded it ended up in a windshear master warning during moderate turbulence. The airplane lagged a little in the transition from the turn and the descent and the electronic glidepath ended up way down. The airplane was on autopilot and pitched down in order to catch up. The airspeed increased rapidly and moments later the windshear warning came. Fortunatedly we were VMC and it only led to windshear escape maneuver / go around.

This happend in an E190. The approach mode (GP) was armed and it all happend on AP with flaps 3 and Gear down.

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#### LV-ARG

##### Well-Known Member
Probably don’t pull up the RNP’s into MSO

Those are RNP AR approaches (this one isn't). They have turning radii turns coded into the procedure (which is not the same as having the FMS anticipating a turn and doing a flyby). The navigation precision this kinds of approaches is usually higher, the design criteria are different, the airline and the crew have to be trained and certified to fly them for some reason.

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#### CFIT99

##### I'm probably commenting ironically...
Those are RNP AR approaches (this one isn't). They have turning radii turns coded into the procedure (which is not the same as having the FMS anticipating a turn and doing a flyby). The navigation precision this kinds of approaches is usually higher, the design criteria are different, the airline and the crew have to be trained and certified to fly them for some reason.
1. Yes it is an RNP, it's stated in the notes on the briefing strip (if it were just a GPS/RNAV it wouldn't require "certification requirements" as in training and op specs)
2. not all RNP have RF legs (especially outside the US but very rare in the US)
3. I'm guessing your company OpSpecs has you set the FMS to a RNP value via a checklist (at least that's what every 121/135 company I have flown has you do)

#### ASpilot2be

##### Qbicle seat warmer
Probably don’t pull up the RNP’s into MSO
Take a look at the rnav z 30 into KEAT.
1. Yes it is an RNP, it's stated in the notes on the briefing strip (if it were just a GPS/RNAV it wouldn't require "certification requirements" as in training and op specs)
2. not all RNP have RF legs (especially outside the US but very rare in the US)
3. I'm guessing your company OpSpecs has you set the FMS to a RNP value via a checklist (at least that's what every 121/135 company I have flown has you do)
I am noticing a few rf legs in the US. So not sure if they are very rare. Also we don't have to set rnp values in our fms.

#### CFIT99

##### I'm probably commenting ironically...
Take a look at the rnav z 30 into KEAT.

I am noticing a few rf legs in the US. So not sure if they are very rare. Also we don't have to set rnp values in our fms.
they are rare not to be RF as in most RNP have them in the US

#### ASpilot2be

##### Qbicle seat warmer
they are rare not to be RF as in most RNP have them in the US
Gotcha! I misunderstood what you wrote initially.

#### inigo88

##### Composite-lover
I'm surprised no one has dropped this one yet. Yeah I know not an RNP approach...

#### SurferLucas

##### Southern Gentleman
I present the MLS 13 into KSUN...this was a MLS built by Horizon Air (one of 4 we operated). This approach is why the Dash 8 has a gear/flap altitude limitation of 15,000ft. Nothing like a 6 deg GS, over mountainous terrain (and sometimes at night). All in a days work flying Dash 8's in the Great Northwest.

#### Autothrust Blue

##### Did Not Grow Up
I'm surprised no one has dropped this one yet. Yeah I know not an RNP approach...
View attachment 43862
The navigational performance is still "required," however.

I present the MLS 13 into KSUN...this was a MLS built by Horizon Air (one of 4 we operated). This approach is why the Dash 8 has a gear/flap altitude limitation of 15,000ft. Nothing like a 6 deg GS, over mountainous terrain (and sometimes at night). All in a days work flying Dash 8's in the Great Northwest. View attachment 43872
Mmmm. "Standard obstacle clearance not provided inside DA(H)." Mmmhm. Good stuff.

Also, you need ALL the equipment.

#### SetClimbPower

##### Well-Known Member
There’s nothing illegal about that approach. Next you’re going to say you’ve never flown a VOR where the inbound and final approach courses are different? To paraphrase the rules: do not descend on the final approach course until outbound the FAF (past or abeam) with a parallel or intercept course. This is where the whole 6 T’s procedure originated from. Rather than a VOR, this is an RNAV approach that requires the inbound course to be different from the final approach course. Most often the cause is terrain.

As for it being a straight-in, the definition of a straight-in approach is one that intercepts the extended runway centerline with no more than a 30 degree intercept not to exceed a final approach gradient of 400 ft/NM. Exceeding either the descent gradient, angle of intercept, or not intercepting the extended runway centerline (e.g. final approach course crosses the middle of the runway or does not intercept until 1000’ past the approach end) requires the approach to be designated a circling only approach.

Sent from my iPhone using Tapatalk

#### jtrain609

##### Antisocial Monster
That there is almost a 90° turn on which you are supposed to be descending. Every other approach I've flown usually has a straight course leading to the FAF, not a turn.

Its perfecly ok to fly something like this VFR, but IMC? little bit weird if you ask me.

Most airlines require you to be fully stabilized by 1000ft agl in order to continue an approach when IMC. In this case, you are probably completing the turn at about 4nm and 1100ft agl which is quite close.

There are a few approaches out there that have turns low to the ground. The RNAV RNP 19 at DCA is an example of this, and has mins of 537' AGL.

https://resources.globalair.com/dtpp/globalair_00443RR19.PDF

Sure, it's an AR approach, but you're not necessarily outside of stabilized approach criteria if you're in a turn.

Now with that being said, I've flown under at least one FOM that said you could only be turning below 1,000' if you HAD to be turning. An RNP or the river visual to 19 in DCA is a good example of that. This allowed these procedures to happen while trying to prevent guys from being configured and stable at 1,000' on a 3 mile left base, when you'd turn final at a mile for no reason other than you were trying to impress yourself.

#### Cessnaflyer

##### Wooooooooooooooooooooooooooooooo
I present the MLS 13 into KSUN...this was a MLS built by Horizon Air (one of 4 we operated). This approach is why the Dash 8 has a gear/flap altitude limitation of 15,000ft. Nothing like a 6 deg GS, over mountainous terrain (and sometimes at night). All in a days work flying Dash 8's in the Great Northwest. View attachment 43872
Funny the fixes are the founder's name.

#### JordanD

##### Honorary Member
I present the MLS 13 into KSUN...this was a MLS built by Horizon Air (one of 4 we operated). This approach is why the Dash 8 has a gear/flap altitude limitation of 15,000ft. Nothing like a 6 deg GS, over mountainous terrain (and sometimes at night). All in a days work flying Dash 8's in the Great Northwest. View attachment 43872
SUN is one of those places we go that I'd be totally happy never having to fly into. If there's a 4 page briefing guide and a check out, it's probably for everyone's benefit I just stay in socal

#### Autothrust Blue

##### Did Not Grow Up
Now with that being said, I've flown under at least one FOM that said you could only be turning below 1,000' if you HAD to be turning. An RNP or the river visual to 19 in DCA is a good example of that. This allowed these procedures to happen while trying to prevent guys from being configured and stable at 1,000' on a 3 mile left base, when you'd turn final at a mile for no reason other than you were trying to impress yourself.
"Report a five mile final."
-beautiful day and nobody around-
"Ask him if he wants that for separation, or if we can do a less B-29-like pattern."