WestJet almost puts one in the drink

[Eric Janson]

I don't have a dog in this fight but there may be a lesson here relevant to all IFR pilots.

Sometimes these situations develop because the crew descends past the MDA without the required visual references in the expectation of the runway appearing soon where they think it is.

Very interesting point. Most companies now treat MDA as DA and at MDA there are only 2 options:-

- See the runway and continue.
- Don't see the runway and go-around.

At my Airline these are the only 2 options on a non precision approach - we are not allowed to fly level at MDA or continue below MDA without seeing the runway.

Losing sight of the runway after descending below MDA is an automatic go-around.

I know not every company has the SOP as simple as this and is is a serious issue imho.

There have been 2 incidents and an accident with Canadian Airlines all involving non precision approaches.

There does seem to be an issue.

[Ancient]

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[rxl]

Nobody saw treating an MDA as a decision altitude as a problem? By it's nature a decision altitude is going to be descended below because it's just that, an altitude at which you decide what to do. If nothing is seen you initiate the go around but guess what, you are still going down at that point and the bigger then airplane the longer it is going to take to start climbing. An MDA is a minimum altitude that you shall not descend below without the required visual reference. If you want to treat it as a decision altitude you better be compensating for that altitude loss and making you decision well before the MDA.

Are large jet operators seriously busting mins like this regularly on non-precision approaches? TC should be all over this.

The answer to your first question is no. My company is adding 50' to all SCDA DA's to compensate for the dip. I would doubt that we are the only ones doing this.

[Eric Janson]

Nobody saw treating an MDA as a decision altitude as a problem? By it's nature a decision altitude is going to be descended below because it's just that, an altitude at which you decide what to do. If nothing is seen you initiate the go around but guess what, you are still going down at that point and the bigger then airplane the longer it is going to take to start climbing. An MDA is a minimum altitude that you shall not descend below without the required visual reference. If you want to treat it as a decision altitude you better be compensating for that altitude loss and making you decision well before the MDA.

Are large jet operators seriously busting mins like this regularly on non-precision approaches? TC should be all over this.

The answer to your first question is no. My company is adding 50' to all SCDA DA's to compensate for the dip. I would doubt that we are the only ones doing this.

My company adds 40' to all published MDA's. The concept of MDA remains valid.

[Ancient]

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[Rockie]

Nobody saw treating an MDA as a decision altitude as a problem? By it's nature a decision altitude is going to be descended below because it's just that, an altitude at which you decide what to do. If nothing is seen you initiate the go around but guess what, you are still going down at that point and the bigger then airplane the longer it is going to take to start climbing. An MDA is a minimum altitude that you shall not descend below without the required visual reference. If you want to treat it as a decision altitude you better be compensating for that altitude loss and making you decision well before the MDA.

Are large jet operators seriously busting mins like this regularly on non-precision approaches? TC should be all over this.

Canadian operators have had a TC waiver to treat a MDA as a DA for many years subject to certain conditions and restrictions. Personally I'm not in favour of it, but TC has studied it and determined that safety is not compromised provided the conditions and restrictions are met. The company I work for does not use the waiver and adds 50 feet to all MDA's to account for the height loss during a go-around.

http://www.tc.gc.ca/CivilAviation/Regse ... n/2509.htm

[J31]

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.

[Surfer Dude]

Sobering though that something as everyday as rain could almost bring down a 737. Stay safe out there.

[Eric Janson]

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[J31]

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!

This is complete nonsense - I've never had this happen in 19000+ hours of flying. That includes 12 years of flying in Monsoon conditions.

I've been in rain that was so heavy we couldn't see the runway at 200'.

Well Eric I have a lot of respect for your comments but that is a cocky response considering the company you are in. This may be a mostly anonymous board with some idiots, but there are also many lurking about with thousands of hours of experience from all over the world.

I have been around the block a few times and can hold my own. Having flown the NG into St Martin many times I can see how rapidly changing weather conditions could cause issues on the approach.

[Jet Jockey]

Our company used to add the 50 feet to the MDA but we don't anymore since TC allows it. We have not encountered any problems with this policy.

There are circumstances in which our SOPs allow the pilots to add the 50 feet to the MDA if they want such as, overweight landing, hot and heavy at higher altitudes, single engine operation to name a few.

The basic idea behind treating the MDA as a DA (with or without adding 50 feet) is that you are doing a SCDA type approach and when you get to your DA and there is no contact, you go around exactly like you would on a LPV approach with a 200 foot DA, or a CAT I approach with a 200 foot DA or even a CAT II approach with a 100 foot DH. There is no dive and drive, waiting for a time X or MAP.

BTW, on a CAT II approach to a 100 DH if you do not rotate the aircraft immediately into the command bars in GA mode, you will possibly hear the 50 foot call from the radio altimeter.

Another exception is a Circling Approach where the "real" MDA is selected. We also set the altitude selector to that MDA so that the A/P can level off. Once the altitude is captured the missed approach altitude is selected.

In all the aircrafts I have flown to a MDA while on A/P, none have leveled off exactly at the MDA and have always ducted under and then climbed back up. The dip was not that drastic but still a dip below. So how come the A/P is allowed by TC to dip under while if you are hand flying the aircraft you are not allowed?

This is why I have no problems flying a SCDA approach that the MDA is treated as a DA even without adding 50 feet to it.

[Eric Janson]

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!

This is complete nonsense - I've never had this happen in 19000+ hours of flying. That includes 12 years of flying in Monsoon conditions.

I've been in rain that was so heavy we couldn't see the runway at 200'.

Well Eric I have a lot of respect for your comments but that is a cocky response considering the company you are in. This may be a mostly anonymous board with some idiots, but there are also many lurking about with thousands of hours of experience from all over the world.

I have been around the block a few times and can hold my own. Having flown the NG into St Martin many times I can see how rapidly changing weather conditions could cause issues on the approach.

I see I was a little harsh in my previous comment - my apologies.

[Surfer Dude]

So how come the A/P is allowed by TC to dip under while if you are hand flying the aircraft you are not allowed?

I'm curious where TC says it's allowed to descend below minimums if you are on autopilot?

[CAL]

the video shows rain and wind at the time.....perhaps a windshear event.....either way no way of knowing what was going on in the cockpit so no need to judge these guys.....they decided to go around.
anyone find out why the runway was closed after?

[Airtids]

http://www.faraim.org/aim/aim-4-03-14-538.html

(e) Atmospheric illusions. Rain on the windscreen can create the illusion of greater height, and atmospheric haze the illusion of being at a greater distance from the runway. The pilot who does not recognize these illusions will fly a lower approach. Penetration of fog can create the illusion of pitching up. The pilot who does not recognize this illusion will steepen the approach, often quite abruptly.

Job well done, as far as I can tell.

[Panama Jack]

There is the misconception of north american pilots, altimeters should be set as soon as you are cleared below transition no matter what FL you are at(outside north america).

Can you please quotes an official regulatory source for this policy?

[amraam]

Another interesting perspective on the attention this has caused:

http://www.nycaviation.com/2017/03/west ... ad-seemed/

amraam

[kevenv]

A CADORS for this incident was just entered yesterday.

[ZBBYLW]

Not sure if it would have helped these guys but on the jet I fly whenever flying a visual or non precision approach we have a PROG page in the FMS where I can get distance from a specified point. In this case I would have put in TNCM09 and cross referenced it when visual if the situation is challenging (rain, black hole, far out etc..) with the exact distance to the threshold it can be easy to reference a 3:1 to make sure you're on profile.

[kevenv]

Interesting video here from a passenger on the plane.

https://www.youtube.com/watch?v=uN3Fd0x0FoQ