FOQA erroneous detections
 

I just received an email from my company telling me l exceeded the stablized approach criteria. Foqa registered a descent rate greater than 1500 feet below 500 feet. It never happened during the flight, when l read the email l thought it was a joke, my first officer called me right after he read the email, we both were confused. Can any engineer or expert tell me how this can happen? Thanks

No idea. Do you have the option to go into the office and see the trace and/or a replay of the approach ( FWIW we do)?

Makes me glad I'm not an airline pilot!

I am definitely not an expert on FOQA, but viewing this incident as a piece of an information system output, it is entirely possible that the wrong record was identified to your flight.
It may be someone else's problem.

This is the first I hear of FOQA department sending emails about anything...They usually use different channels, but I digress...

It's not entirely impossible to momentarily hit a high descent rate down low (or to have an erroneous VS indication), which is why I'm surprised that your flight got tagged based on that one parameter. Usually FOQA doesn't flag a flight unless a number of parameters were exceeded.

So, I guess my question would be what more there is to the story here...

VSI, rate of change of pressure altitude, or radio altimeter ?

Wind speed, gusts, both pressure altimeters on the same pressure setting ?

Compare with previous flights in the same location.

Data source, recording rate, accuracy, analysis software ?

Aircraft configuration, change in flap / gear, yaw / roll (airflow - pressure crossflow between sensors) ?

As far as I am aware, those flight data monitoring systems are highly customizable by individual airlines and their trigger values are subject to change as needed. If a certain setup shows a lot of false warnings, it may well be adjusted not to raise unwanted false alarms any more. This has happened more than once already. It also may find it hard to differentiate between a bog standard Cat I ILS or a more taxing approach, say, with a glideslope angle of 5° that obviously requires sink rates greater than standard, even more so when correcting a slight deviation like 3 whites/1 red. It is is one of the analysts jobs to filter such unwanted alerts out and not tarnish the system by pestering the crews with heaps of unwarranted envelopes.

That said, the other side of the coin is that such a system may take note of exceedances that happened only for a fraction of a second and were immediately corrected. It has also been said that several crews that have been invited for a reenactment of the flight phase in which the system fired a warning were rather surprised at the situation in retrospective; it did not seem all that interesting to them while it occurred.

It is hard to deliver a diagnosis here. It may well be that the collected data is erroneous; that theory might be verified by checking several of the individual aircrafts flights around the one in question for occurrence of the same finding. It is possible as well that we are talking about an approach here that has a certain tendency or even an approval for higher sink rates while still being formally stabilized. Also, there have been findings from that system that looked weird in isolation, but a synoptic view with more data from that flight showed it to be perfectly normal.

Exactly that happened to me about 10 years ago, resolved very quickly by the flight safety manager who was very embarrassed by the whole thing so definitely worth checking.

I had an e-mail last year saying I had busted the landing gate and landed, they noted I had filed an ASR, my reply was that on that date I was at home enjoying a Beer so it was more than likely someone else. They had got it wrong and apologised profusely.

Those systems do record erroneous data from time to time...., a couple years ago I had a notification that the flap 30 speed had been exceeded......, we were at .81 and FL390 with the flaps up (of course) when it registered the overspeed...., go figure!

I would just add to the above that you should request to see the entire record. In our experience, instantaneous readings can (and do) go momentarily out of bounds - particularly when ADIRU is the source or when the bounds are triggered by an input that monitors analogue state changes.

Remember, computers make very fast, very accurate mistakes.

Normally, "instantaneous" readings, (data spikes or very short-term valid excursions) are filtered by the design of the FOQA Event usually by requiring a certain amount of time, say 3 seconds for example for a high-rate-of-descent Event, to ensure that that's what was going on, and it wasn't just short, transient, ("going through the red light") value. Excursions occur all the time, and, particularly if the approach is rapidly re-stabilized, our program leaves such excursions out of the data. We call crews, we do not send emails and the discussion is a welcome one as the crew is often as curious about what FOQA shows as we are about learning from the occurrence.

Also, I am a very strong believer in pilot-run FOQA programs, or at least having active line pilots watching the data on a regular basis and doing the crew contacts under the direction of the FOQA Program Manager. I know this is may seem unrealistic to many but in my experience, (running FDM since the late 80's and flying the line), avoids many of the pitfalls like the one being cited here.

FOQA Programs need to be tailored to the airline's operation and designed and implemented to reflect the air carrier's safety culture. To reinforce something stated above, there are as many ways to do flight data monitoring as there are programs and no two are alike.

Have you ever seen a radar altimeter just go nuts for a few seconds. I have seen it and it caused the same thing and I got a call from our FOQA gate keepers, (pilots) and he said forget it. He just had to call and later he followed up that the next day the captains radar altimeter failed and had to be replaced.

It happens.

If ever you get called up for tea and bikkies over an alleged CVR transcription event and the transcription is shown to you on paper, make sure you demand to hear the tape from which the transcription was made. in other words don't take what was written down as what was really said.

A pilot was accused of being impatient on the radio and a violation filed using the written transcription by a clerk in the DCA (Australia) accident investigation office as evidence. Three R/T transmissions by the pilot was offered as evidence. One was "Request Airways clearance" but written down as "are we clear"

Another was "Ready 30 seconds" which was an authorised terminology in AIP meaning we are ready for take off but need 30 seconds in the lined up position.
The investigating official used that transmission as evidence the pilot was in a hurry and therefore impatient.:confused:

Thanks to all of you
 

I really appreciate the replies I received, l forgot to mention that my employer is an Asian carrier, having said that, pilots who work or have worked in this part of the world know what l mean, common sense is a very rare commodity here. I had a meeting with my chief and to put it in a nutshell, my conversation could have been more productive if l had it with a wall. Next week l m going to review the data with the foqa team, l requested an hearing. Thanks again to all of you

All I can add is that when I did FOQA, every flight that had been flagged by the computer had to be reviewed by me (the FOQA pilot) and if the parameters didn't make sense, it was immediately binned. Almost 30-50% of flights that have been flagged by the FOQA system were "false positives" and separating the chaff was a big part of my job...

Then again, it was in an European company. I too know first hand how sometimes things work in Asia... :ugh:

If you get the chance of seeing your flight's record, check for consistency with other parameters, like pitch, thrust, speed, radio altitude change, G/S deviation etc. if you really had 1500ft/min sink rate on approach, the other parameters would show too. Good luck!

gf:

For the U.S. airline pilots this is one of areas where ALPA, APA, et al, are very effective.

From AC120-82, this seems to be a High Descent Rate exceedance. The basic algorithm should be "Descent rate > x fpm for x seconds", so if properly implemented, you can rule out transient instrument errors. Would suggest checking what the monitoring window is for this event and if possible the FPM and altitude plotting for this particular descent. Since your FDM software has the data, I would guess it should be readily available for your review.

This is my first post in this forum, I am an engineer getting started with FOQA implementation for our product.

aterpster, re "For the U.S. airline pilots this is one of areas where ALPA, APA, et al, are very effective.":ok:, and, I will add, also with air carriers in Canada.

I've certainly had that experience myself. Got a call from flight ops about a flight operated by a near namesake with a similar surname. I was concerned by the initial tone of the call but when they told me the sector, I realized that it was one that I didn't operate. I couldn't resist reeling in the hapless management pilot a little when I told him that he would have to drop my next trip with pay and then I would come in to discuss the situation on my assigned duty days, not my days off. He repeatedly emphasized that any counseling and training offered was totally non-punitive. I quickly resolved the issue by giving my employee number, he agreed that it wasn't me and was apologetic. And I sure didn't want to jerk him around too much because someday it might really be me at the end of that long green table with no ashtray. ;)

I'll observe that over the years these safety monitoring programs always seem to start out as 'totally non-punitive' and sometimes morph into something else. I believe the NTSB has already come out in favor of random CVR auditing and cockpit cameras. I'm sure when these innovations come we'll be similarly assured that any information garnered can never be used for punitive purposes.

A couple of decades ago two of my colleagues were accused of flying under a bridge on a night visual approach to a West Coast airport, perhaps PDX or SFO, I'm not sure. Some nimby volunteer noise warden called the FAA to report the sighting and the feds took a look at their radar data. Sure enough, one of our planes showed a very low altitude on final over the water although the time seemed to be a couple of hours off. Don't know if they were able to get the data from the plane's FDR or QAR but it turned out that the Mode C encoder on that aircraft was intermittent. Apparently the controller made a remark to that effect but perhaps the crew didn't write it up at an outstation back in the day.