WestJet almost puts one in the drink

[shamrock104]

When this was first reported Westjet commented that there was nothing unusual about the first approach. Now that there's a CADOR report on this I wonder what their comment is now?
Transparency throughout may have been the better way to go.

[pelmet]

On a RNAV or VOR approach the MDA +50 ft is considered a DH at WJ. I do not believe they descended below that without visually acquiring the REIL's, PAPI's, and/or the runway.

Now those who have flown into St Martin will also note the missed approach point (MAP) is at 1.9/2.0 miles from the runway depending on the approach. If you do not acquire the required visual reference the missed approach it is an immediate climbing right turn. If you do acquire the required visual reference, once past MAP in the B73 NG you no longer have electronic vertical guidance. It is now a visual profile to the runway relying on the REIL's, PAPI's, and runway environment.

Now consider the scenario:

You are passed the MAP, visually hand flying to the runway and encounter a heavy rain shower. At 400 ft AGL and 30 seconds from touchdown, windscreen is suddenly pelted by rain as you call for non flying pilot to turn the windshield wipers on. In reduced visibility but with the PAPI's still in sight you realize the aircraft is trending below the "visual" glide slope. Power up. In descending air from the rain shower the VSI goes from a stable 750 fpm to 1000 fpm. More power to arrest the descent, PAPI's are going red, Go around!

Smile.....pictures being taken to be analyzed by the armchair quarterbacks.

It is actually quite simple what to do. The RNAV approach places you on a 3 or near 3 degree descent path to the runway with minimums at whatever altitude. The actual angle can usually be seen on the approach chart and it shows a continuation to the runway threshold. With GPS updating this will be very accurate. The aircraft is stabilized on descent at minimums at which point you have the required visual references but they are fuzzy or not clear with good depth perception. Because the required visual references are in sight, you continue the same descent rate.

Push the VS button(or FPA if you are lucky enough to have it) and stay partially inside while maintaining the same descent rate using the flight director bars. In a few seconds, you are clear of the rain or close enough to the runway to have proper depth perception. If for some reason you are not using the VS function of the flight director to follow, then simply concentrate on maintaining the same rate of descent which is probably best done by holding the same pitch attitude used in the latter stage of the approach that led to a stable descent.

Looking mostly outside too early is a recipe for an unintended improper descent rate leading to further problems. Not that I am suggesting that this is what happened in this case, but it is a plausible scenario.

[Eric Janson]

The video posted previously (from the cabin) shows the aircraft flying low over the water for 25 seconds before a go-around is made. It's already low when the video starts so the actual time spent this low is even greater.

This directly contradicts most of the "spin' posted previously.

[TG]

Meanwhile in St Maarten...

[Jean-Pierre]

I would rather see the balked landing due to what look like shear on short final than skimming the surface of the ocean for half a minute with no action taken.

[pdw]

Consider 10sec there might even be ground effect after possible "shear" at 500-1000'.

ps: : "Skimming the surface" would have IMO been short in comparison

['97 Tercel]

Shear effect 300'. Zone flow + downwind quartering variable wind component. Thrust vector?

[GyvAir]

https://www.youtube.com/watch?v=fVq4_HhBK8Y

[Eric Janson]

I would rather see the balked landing due to what look like shear on short final than skimming the surface of the ocean for half a minute with no action taken.

Looks more like the drift was misjudged when they saw the runway and they ended up on the downwind side with not enough distance to correct.

Easy to do.

This should have been a go-around but it became a balked landing - this would require an ASR at my Airline.

[pdw]

Shear effect 300'

Okay .. what made you pick 300 ?

[CL-Skadoo!]

Thrust vector?

I guess it could

Low level funnel gunnel?

[mbav8r]

Thrust vector?

I guess it could

Low level funnel gunnel?

Never thought of that, I was thinking dipsy doodle or maybe an oopsie daisy but I think your funnel gunnel is more likely to blame

[DropTanks]

Thrust vector?

I guess it could

Low level funnel gunnel?

O M G! Love that movie!

Talk about an obscure reference.

[Donald]

Final report:

http://tsb.gc.ca/eng/rapports-reports/a ... 7f0052.asp

[Eric Janson]

A very close call - crew were very lucky to get away with it imho.

Just re-read the thread - once again an awful lot of people dismissing this as a 'Non Event'. Even after the photos were published.

Maybe someone should show the report to Lauren Stewart.

[pelmet]

Haven't read it all but....

"On final approach, the aircraft was stabilized on a 3° angle of descent and configured for landing. Approximately 0.5 nm before the MAP, the flight crew decided that, given that they had the shoreline in sight and expected to see the runway shortly afterward, they would continue the approach visually. At that point, the aircraft was descending at approximately 820 feet per minute (fpm) and at 159 knots indicated airspeed, with an N1 of approximately 62%.
The pilot flying (PF) then disconnected the autopilot as per WestJet's approach procedures for landing at TNCM. Shortly afterward, the PF reduced the pitch from 0.5° nose up to 1.2° nose down, which initiated an increase in airspeed. In response to the airspeed increase, the autothrottle command reduced the engine thrust from 62% to 52% N1 to maintain the 160-knot speed previously set in the flight management computer (FMC). Following the reduction in thrust, the aircraft began to deviate below the 3° angle of descent, at a descent rate of between 1000 and 1150 fpm. Shortly after, the PF cycled the flight directors and started to manually manipulate the thrust as per WestJet's approach procedures for landing at TNCM. The reduction in the pitch attitude led to an increase in airspeed, which resulted in a reduction in engine thrust and a higher rate of descent than that required by the 3° angle of descent."

If you are on a three degree path to the runway, you obviously want to make sure you remain so after disconnecting the autopilot. Depending on how the FMC is configured, on some Boeings, the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars. If familiar with the FMC waypoints, you can tell this by looking at the waypoints in the FMC. Then you can just follow command bars while having your marginal but legal required visual references which in reality, provide little depth perception and quite possibly, misleading cues.

If for some reason, you won't be using the flight director cues from the FMC generated path, you might consider using the VS function to give you similar flight director guidance or the more accurate Flight Path Angle if it is installed. A simple push of the appropriate button at the desired, stable descent rate give a continuation of what you already have. But even without this stuff, you can do just like in the good old days......if you know you are on the proper descent angle, just maintain the same rate of descent which can be maintained by keeping the same pitch once the autopilot has been disconnected. Just because the autopilot is off doesn't mean you can't continue to look inside and fly the aircraft on instruments while the other guy is monitoring both inside and outside with the required visual references until clarity with its proper depth perception slowly or quickly comes into view.

There can be a tendency to inadvertently push or pull on the control column once visual if the PF changes most or all focus to the outside environment, especially in marginal conditions. Good discipline can prevent this, perhaps by making a mental note about it at an earlier time to prevent this situation. Sometime it is just best to stay on the instruments for a little while longer.

[Noo]

"the crew cycled the flight directors, in accordance with WestJet's approach procedures for landing at TNCM"

Does this mean turn the FD's off then on again? Is this a common practice for the 737? Why would they do this?

[ahramin]

You turn the FDs off so that you aren't following a made up glide path below minimums. They are cycled so that they are available for the go around.

the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars.

This is exactly why accidents and incidents like this will continue to happen. Continuing past minimums without enough visibility to land visually may work out most of the time, but most of the time isn't good enough.

Then you can just follow command bars while having your marginal but legal required visual references

is the perfect recipe for an AC624 or worse.

Go arounds are your friend. It's easy, you've practiced it in the sim, your day will be fine. If you are 300' above minimums and not quite sure if you can see enough to continue to land, continue to minimums. If you are AT minimums and not quite sure if you can see enough to continue to land, Go Around Flaps.

[Noo]

So you turn the FD's off and then on again right way? What are they displaying when you turn them on again?

[Go Guns]

That particular approach, the missed approach point is 2 miles shy of the runway, the next waypoint after the MAP is on the missed approach procedure, nowhere near the airport. So if you followed the FMC information via the flight directors, it would not take you to the airport. So, at the MAP with the required visual reference, autopilot disengaged, cycle the flight directors. This will kick the autothrottle into ARM mode, and blank the FMA and the flight directors. Should you press TOGA, the flight directors will come alive with LNAV and TOGA, autothrottle will be in GA.

[shamrock104]

It's a shame about their lack of transparency on this, maybe now with the initial report published they will make some sort of a statement but I don't believe they will.

[pelmet]

the path of some non-precision approaches in the FMC will take you to 50 feet above the runway in a proper position to land with command bars.

This is exactly why accidents and incidents like this will continue to happen. Continuing past minimums without enough visibility to land visually may work out most of the time, but most of the time isn't good enough.

Then you can just follow command bars while having your marginal but legal required visual references

is the perfect recipe for an AC624 or worse.

Go arounds are your friend. It's easy, you've practiced it in the sim, your day will be fine. If you are 300' above minimums and not quite sure if you can see enough to continue to land, continue to minimums. If you are AT minimums and not quite sure if you can see enough to continue to land, Go Around Flaps.

Almost every airline pilot has been in a situation like these guys were in. Half mile back from the MAP with some visibility. If they had just continued on their path to minimums as you said, then they could have made their decision. Instead, according to the report, they decided to "continue visually" at which point the pitch was decreased significantly and things went downhill from there. Perhaps they were trying to duck under a cloud base.

My recommendations are perfectly fine. It is not a recommendation to do this sort of thing to 50 feet on instruments, it is just not to go 100% visual right away. Continue with the stable approach with your required visual references but difficult depth perception(because you are over water) until things are clearer. It could apply on a clear black hole night as well.

Before we start writing exaggerated replies talking about this will lead to accidents, one need only look at figure 3 in the report. While I realize that it is only a simulation of the approach, it is a perfect example of having the required visual references in a murky condition with no depth perception. There is no reason to go around with this picture being presented to the pilots but good reason to continue with 80% or more of the PF's concentration being inside and continuing the approach on the path or continued normal rate of descent depending on the technology available.

It is difficult to know what exact picture was presented on that approach but I have read more of the report it seems to hint that the hotel was misidentified as the runway based on its shape and quite possibly in my opinion because it was the thing that was most visible in the murky view as compared to the actual runway.

If you are on an FMC generated(through GPS updating) typical descent path to a runway and in murky/night conditions and it appears that you have to make a significant change to the current path to align laterally or vertically with the runway, start wondering if you have misidentified the runway.

[Dry Guy]

The poster a few above you said the FMC would not take you to the airport. I guess there is no waypoint there? So following your FD's to continue the approach apparently would not work.

[pianokeys]

It's a shame about their lack of transparency on this, maybe now with the initial report published they will make some sort of a statement but I don't believe they will.

YEAH DONT WORRY ITS ALL OKAY! NOTHING TO SEE HERE! NORMAL!

[confusedalot]

The poster a few above you said the FMC would not take you to the airport. I guess there is no waypoint there? So following your FD's to continue the approach apparently would not work.

Too lazy to read the whole thread but I get the gist.

I confirm to anybody out there that the FMC, if properly set up, will get you to the threshold of the runway at the proper altitude and the proper position. It's been doing that since 1988 from my first experiences with the equipment and well before that, even before gps became popular. IRS, DME/DME, VOR/VOR, VOR/DME, and all of those sort of rnav combinations get you to your target.

Most pilots keep an eye on their magic even if they are visual. Yet, we as humans, do in fact get distracted. They fell into the trap, and that is not a condemnation or judgement. Shit happens as they say. Those two will never fall into that trap again.

Height judgement over water in reduced visibility is a bit tricky in my experience, but that's just me.