Ocean Close Call in St. Maarten

I don't think it was really as close a call as people like to make it out.
 
Fell under the glide path for sure. I saw the same video on YT titled "B737 almost CRASHES into water at Princess Juliana."

I didn't see any 'near crash' just another over hyped event.
 
MauleSkinner said:
I don't think it was really as close a call as people like to make it out.
Click to expand...
Depends on your definition of close call. Either way, the video and stills completely fly in the face of WestJet's claim that the aircraft never went below 500'.
 
I don't know about this one. If you cover up the "trail" in the water and compare the "low" to the "normal" approach, they look pretty similar. I think the shading in the water causes an optical illusion.

Edit: I just watched the video too...that was definitely below 500 ft.
 
Larry in TN said:
No glide path. Only non-precision approaches.
Click to expand...

You must not fly an airplane that considers any VNAV profile to a runway to be a "glide path". In my equipment, we specifically use that term during non-precision and visual approaches not backed up by an ILS.
 
I dunno, I can see doing a go-around when the beach is packed with bikini's, but for a lil wind? sheesh, rookie.
 
I fly 737NGs and SXM is one of the destinations I fly them to.

The airplane in the video was likely flying the RNAV approach in LNAV/VNAV. I was just trying to point out that there is no glide slope; however, the DDA used on that approach flown in VNAV would be 750' (MDA+50) and the VNAV-path is unusable below DDA/DA (as it can't provide terrain/obstruction clearance). The flight was well below DDA in the video so the VNAV-path was not applicable.
 
Larry in TN said:
The flight was well below DDA in the video so the VNAV-path was not applicable.
Click to expand...

You guys are still using a DDA when the runway has a PAPI or VASI? We stopped doing that a couple of years back, although it still rubs the instrument student in me the wrong way to think that there actually *is* a situation where we can legally go below the MDA, if just momentarily. ;)
 
eman1200 said:
I dunno, I can see doing a go-around when the beach is packed with bikini's, but for a lil wind? sheesh, rookie.
Click to expand...
Maybe the FO was on IOE or he simply got distracted by a hot chick on the shore line (which is understandable), either way it was a happy ending.
 
kayoh190 said:
You guys are still using a DDA when the runway has a PAPI or VASI? We stopped doing that a couple of years back, although it still rubs the instrument student in me the wrong way to think that there actually *is* a situation where we can legally go below the MDA, if just momentarily. ;)
Click to expand...
You might want to check your FOM. I just looked at the approach plate for the RNAV 10 at TNCM. I don't think we would be able to use C073 to use the MDA as a DA. We'd have to use a DDA there. I'm sure most other operators are the same.
 
Last edited:
kayoh190 said:
You guys are still using a DDA when the runway has a PAPI or VASI?
Click to expand...
Depends on the approach. This one has neither the "DA(H)" minimums nor the ball-note* allowing MDA to be used as a DA so the DDA would apply.

*"Only authorized operators may use VNAV DA(H) in lieu of MDA(H)"
 
Yeah, I wasn't thinking about a specific approach. This was a global change that applied to all non-precision (we call them non-ILS these days) approaches. When the change happened (maybe two years ago?), it seemed wrong to us then, and to a certain extent, it still does. Fortunately, very rarely do we fly a non-ILS approach to an MDA - almost everywhere we go has an RNAV option that'll get us down to a lower DA. But regardless, let me show you the verbiage from my airplane's OM 1 (FOM to you guys):

Derived Decision Altitude (DDA). Non-ILS approaches with only LNAV or MDA(H) minimums are flown to a DDA, obtained by adding fifty (50) feet to the MDA(H) value associated with the approach procedure. If a VASI or PAPI serve the runway, then the MDA may be used as DA. This DDA will be the altitude at which the missed approach will be initiated if necessary. The insertion of this altitude in the BARO minimums will prevent the aircraft from descending below the MDA(H) during the initiation of a missed approach procedure. Standard approach callouts are made in reference to the DDA (e.g., “Approaching Minimums”).
Click to expand...

The bolded part is what was added to our manual. It even reads like an addition, because it doesn't fit with the rest of the text.

I thought maybe this was an airplane thing, so I also pulled the OM 1 for the 737:

MDA may be used as a DA if in VNAV PTH and the approach has a coded GP in any of the following three situations:
• Ball note reads: “Only authorized operators may use VNAV DA in lieu of MDA”, or
• Runway has a published ILS approach (applies when conducting an ILS with the glideslope inoperative or a LOC approach), or
• Runway has a VASI or PAPI.
In all other cases, set a Derived Decision Altitude (DDA), equal to the published MDA + 50 feet.
Click to expand...

Again, the bolding is mine. Is it possible the 737 only has a coded GP for approaches that already have DA minimums? That might explain things - my airplane uses a coded GP even for VOR approaches, so again, even with a vanilla VOR approach to an MDA, I'm treating it as a DA (assuming the PAPI or VASI is there).
 
Larry in TN said:
I was just trying to point out that there is no glide slope; however, the DDA used on that approach flown in VNAV would be 750' (MDA+50) and the VNAV-path is unusable below DDA/DA (as it can't provide terrain/obstruction clearance). The flight was well below DDA in the video so the VNAV-path was not applicable.
Click to expand...

Incidentally while digging through the 737 manual, I noticed a note that matches what you wrote here, which goes further to say that VNAV guidance actually ceases at the MAP, with you guys needing to manually fly the airplane to the runway during the visual segment. Am I reading that right? That might explain why I see "glide path" differently than you do. We get guidance all the way down to the runway (regardless of whether it's usable in a TERPS sense) and indeed can leave the AP coupled to that path until as late as 50' AGL. Of course in practice the AP is off long before that, but always having that FD guidance staring you in the face gets you thinking about glide paths in just about any situation where there's no glide slope.
 
kayoh190 said:
Yeah, I wasn't thinking about a specific approach. This was a global change that applied to all non-precision (we call them non-ILS these days) approaches. When the change happened (maybe two years ago?), it seemed wrong to us then, and to a certain extent, it still does. Fortunately, very rarely do we fly a non-ILS approach to an MDA - almost everywhere we go has an RNAV option that'll get us down to a lower DA. But regardless, let me show you the verbiage from my airplane's OM 1 (FOM to you guys):
Click to expand...
Yeah, we do the same for non-ILS approaches too, with some differences, which I think are interesting.

Let me ask you... at your carrier, if you were faced with flying to a runway served by an ILS but the GP was NOTAMd OTS and it did not have any VGSI (VASI or PAPI), would you use a DDA or fly to the MDA as a DA?
 
We're saying the same thing but using different terminology. Our respective manuals just address it differently.

The ball-note I referenced above is included by Jepps on approaches which meet the requirements of C073. There should not be a situation where C073 applies to a published MDA(H) minimum where the ball-note is not included.
 
kayoh190 said:
Incidentally while digging through the 737 manual, I noticed a note that matches what you wrote here, which goes further to say that VNAV guidance actually ceases at the MAP, with you guys needing to manually fly the airplane to the runway during the visual segment. Am I reading that right? That might explain why I see "glide path" differently than you do. We get guidance all the way down to the runway (regardless of whether it's usable in a TERPS sense) and indeed can leave the AP coupled to that path until as late as 50' AGL.
Click to expand...
We have the guidance displayed all the way to touchdown but it is not usable below the published MDA because it has not been evaluated for obstruction clearance on a non-precision approach as it is on an ILS or GLS. I am surprised that you can stay coupled to the VNAV-Path below published MDA.

The autopilot must be disconnected by 50' below MDA/DA on non-precision approaches. That is from the Limitations section. Minimum altitude on non-autoland ILS/GLS approaches is 50' AGL.

Sluggo63 said:
Let me ask you... at your carrier, if you were faced with flying to a runway served by an ILS but the GP was NOTAMd OTS and it did not have any VGSI (VASI or PAPI), would you use a DDA or fly to the MDA as a DA?
Click to expand...
We would use MDA as DA if the C073 ball-note was published, DDA if it was not.
 
Sluggo63 said:
Let me ask you... at your carrier, if you were faced with flying to a runway served by an ILS but the GP was NOTAMd OTS and it did not have any VGSI (VASI or PAPI), would you use a DDA or fly to the MDA as a DA?
Click to expand...

I'd use a DDA. But my airplane's OM doesn't make any exception for runways with an ILS approach, as the 737 OM does. Their manual makes me think they'd fly your scenario down to a DA. Of course not being on that airplane, I don't know. I'll let you know in a month, as I'm changing bases and will be headed to transition training in the 737. :)
 
He's obviously low but executed a nice go around procedure and a nice 2nd approach. I'm having a tough time seeing this as newsworthy.
 
Larry in TN said:
I am surprised that you can stay coupled to the VNAV-Path below published MDA.

The autopilot must be disconnected by 50' below MDA/DA on non-precision approaches. That is from the Limitations section. Minimum altitude on non-autoland ILS/GLS approaches is 50' AGL.
Click to expand...

Yeah, since we're visual to the runway at that point, there's no guidance as to how we use the automation to get there. The aircraft limitation is 50' AGL in all cases (unless doing an autoland, of course). Back in my MD-80 days, it was like yours - 50' below the MDA. My guess is that when I head over to the 737 I'll be back to treating it identically to the way you do.

I see your point about the ball note, but the way my manual reads, I don't think we're required to have it there to use an MDA as a DA. My plane doesn't fly to SXM, but looking at the RNAV to 10, I think I'd fly it to 700'.
 
To be fair, that's a pretty common thing in SXM. I bet they were planning to buzz the crowd, noticed they got a bit too low and went around. You see that almost daily.
 
Sluggo63 said:
Let me ask you... at your carrier, if you were faced with flying to a runway served by an ILS but the GP was NOTAMd OTS and it did not have any VGSI (VASI or PAPI), would you use a DDA or fly to the MDA as a DA?
Click to expand...

Larry in TN said:
We would use MDA as DA if the C073 ball-note was published, DDA if it was not.
Click to expand...

kayoh190 said:
I'd use a DDA. But my airplane's OM doesn't make any exception for runways with an ILS approach.
Click to expand...
This is what's interesting to me. All three of our carriers use some sort of C073 Exemption to fly a Non-ILS approach down to a MDA as DA, but they all have different procedures.

We can use an MDA as DA if (1) We have the "authorized operators" ball note OR (2) We are flying an ILS approach with the GS OTS (no ball note needed). We can not use the VGSI exception.

Now Larry has to have the ball note, no ILS/GS OTS or VASI exception.

Kayoh only has the VGSI exception, no ball note or ILS GS OTS exception.

Odd, we're all using C073 but our airlines are picking and choosing what parts they want to use.
 
Larry in TN said:
I fly 737NGs and SXM is one of the destinations I fly them to.

The airplane in the video was likely flying the RNAV approach in LNAV/VNAV. I was just trying to point out that there is no glide slope; however, the DDA used on that approach flown in VNAV would be 750' (MDA+50) and the VNAV-path is unusable below DDA/DA (as it can't provide terrain/obstruction clearance). The flight was well below DDA in the video so the VNAV-path was not applicable.
Click to expand...

Y'all got it nice. We still do the old 1500' FPM dive and drive. We have VNAV and LPV but aren't allowed to use it. It's annoying as he$$ because I'm having to change the autopilot settings every few seconds.
 
Here's what C073 looks like for those who might be interested. This is a generic version from the FAA web site. The actual OpSpecs is customized to the specific airline.

Appendix A. Sample OpSpec C073, Vertical Navigation (VNAV) Instrument Approach Procedures (IAP) Using Minimum Descent Altitude (MDA) as a Decision Altitude (DA)/Decision Height (DH): 14 CFR Part 121
a. The certificate holder is authorized to use minimum descent altitude (MDA) as a decision altitude (DA)/decision height (DH) with vertical navigation (VNAV) on a Nonprecision Approach (NPA). Certificate holders will use C073 in conjunction with operations specification C052, Straight-In Non-Precision, APV, and Category I Precision Approach and Landing Minima—All Airports. The certificate holder is authorized to conduct instrument approach operations using the following aircraft and Area Navigation (RNAV) systems certified for these VNAV operations as listed in Table 1.
Table 1—Authorized Aircraft and Equipment

Airplane Type (M/M/S)

Area Navigation System (Model/Version)

Remarks

b. Public Vertically Guided Instrument Approach Procedure (IAP) Assessment. Obstacle clearance surface (OCS) assessments protect the instrument procedure, including the missed approach. Glidepath qualification surface (GQS) assessments protect the landing area and are accomplished on 14 CFR part 97 IAPs with a published DA/DH. These approaches conform to the U.S. standard for Terminal Instrument Procedures (TERPS) and include instrument landing system (ILS), Ground Based Augmentation System (GBAS) Landing System (GLS), RNAV Required Navigation Performance (RNP), and RNAV Global Positioning System (GPS) IAPs with a localizer performance with vertical guidance (LPV) DA and/or lateral navigation (LNAV)/VNAV DA.
Note: The use of MDA as a DA/DH does not ensure obstacle clearance from the MDA to the landing runway. Operators must see and avoid obstacles between the MDA and the runway when 14 CFR part 91, § 91.175 requirements are met and the approach is continued below the MDA for landing.

c. Authorized Approaches. The certificate holder may fly all part 97 nonprecision straight-in IAPs listed as authorized in their C052, Table 1, columns 1 and 2, using an MDA as a DA/DH if the approach meets one of the following requirements and its subcomponents:
(1) Serves a runway that has a published RNAV IAP (“RNAV (GPS),” “RNAV (RNP),” or “GPS” in the title) with a published LNAV/VNAV or RNP DA, and:
(a) Has the exact published final approach course as the RNAV IAP.
(b) Has a published vertical descent angle (VDA) coincident with or higher than the barometric vertical guidance (glideslope (GS)) on the published RNAV IAP.
1 A published VDA is not required when using the LNAV minima line on an RNAV approach that has a published LPV and/or LNAV/VNAV DA. Use the published GS. The VNAV path must be at or above all stepdown fixes.
(c) Is selected from an approved and current database and the flight management system (FMS) displays a final approach Flight Path Angle (FPA) in tenths or hundredths. The displayed FPA may have a maximum difference of minus .04 degrees from the IAP VDA or GS. The displayed FPA may always be rounded up to the next tenth. The range for a given FPA will be 2.9 to 3.0, 3.1 to 3.2, 3.2 to 3.3, 4.0 to 4.1, etc. This applies to systems that display the FPA in tenths or hundredths.
Note: Aircraft without an FMS FPA display meeting previous AC 20-129 criteria may have been approved for LNAV/VNAV approaches using barometric vertical navigation (baro-VNAV). Certificate holders currently approved C073, using AC 20-129 criteria, may continue C073 operations.

(2) Serves a runway that has a published ILS, GLS, or RNAV IAP with LPV minima, and:
(a) Has the exact published final approach course as the ILS, GLS, or RNAV IAP.
(b) Has a published VDA coincident with or higher than the electronic GS on the published ILS, GLS, or RNAV IAP.
1 A published VDA is not required on a LOC-only approach when the ILS GS is out of service. Use the published GS. The VNAV path must be at or above all stepdown fixes.
2 A published VDA is not required when using LNAV minima on an RNAV approach that has a published LPV or LNAV/VNAV DA. Use the published GS. The VNAV path must be at or above all stepdown fixes.
(c) Is selected from an approved and current database and the FMS displays a final approach FPA in tenths or hundredths. The displayed FPA may have a maximum difference of minus .04 degrees from the IAP VDA or GS. The displayed FPA may always be rounded up to the next tenth. The range for a given FPA will be 2.9 to 3.0, 3.1 to 3.2, 3.2 to 3.3, 4.0 to 4.1, etc. This applies to systems that display the FPA in tenths or hundredths.
Note: Aircraft without an FMS FPA display meeting previous AC 20-129 criteria may have been approved for LNA/VNAV approaches using baro-VNAV. Certificate holders currently approved C073, using AC 20-129 criteria, may continue C073 operations.

(3) Serves a runway to an airport operating under 14 CFR part 139 with a Visual Glide Slope Indicator (VGSI).
(a) The VDA or GS on the published final approach course must be coincident with or higher than the published VGSI descent angle.
(b) The published final approach course is within plus or minus 4 degrees of the runway centerline (RCL) course.
d. VNAV Path Angle. The VNAV path angle must be greater than 2.75 and less than 3.77 degrees for Category A, B, and C aircraft, and greater than 2.75 and less than 3.50 degrees for Category D/E aircraft.
e. Operational Restriction. Certificate holders will not use an MDA as a DA/DH if the requirements specified in this operations specification are not met. The certificate holder may use a continuous descent final approach (CDFA), but will begin the missed approach at an altitude above the MDA that will not allow the aircraft to descend below the MDA.
f. Required Training. Flightcrews must be trained in accordance with the certificate holder’s approved training program for the navigation system and instrument procedure being used before conducting any operations authorized by this operations specification.
 
Based on how vigorously the umbrellas were being whipped on the beach, I was guessing that wind shear was a significant factor. SXM and a number of the other islands (e.g., Tobago) are notorious for winds that trip over the mountains and tumble down the approach path. Also, the Juliana metar often indicates something along the lines of "winds 090 at 17 but varying between 20 and 160 degrees", but I'm not sure what the metar might have read at the time of this particular approach.

SXM is leading into the height of the dry season. This is when the winds are generally their most lively. I've been grounded here for a number of days during the current dry season due to the winds.

mtuomi said:
To be fair, that's a pretty common thing in SXM. I bet they were planning to buzz the crowd, noticed they got a bit too low and went around. You see that almost daily.
Click to expand...
 
Last edited:
You must log in or register to reply here.
Back
Top