@FSX09pilot In this particular case they used the APP mode of the autopilot, obviously down to below 800ft as LAND3 was activated by the autopilot in the latter part of the decent. The autopilot would use Trim to adjust decent rate. If it was being flown manually, the pilot would use a combination of Yoke, Trim and Throttle to adjust decent rate and pitch.
doesnt answer the question, as to why the crew placed total reliance on an ils dme approach when they knew it was un-monitored before they left the ground?
So you suggest they should do what? a non-precision VOR approach even when theyre recieving Ident and 'on path and slope' indications with the Autopilot accepting land3? They were slightly suspicious of the ILS which is why they monitored the ident all the way down. *beeps in headset all approach.*ILS use would be normal here with 'caution' (ie monitoring DME and Ident and doing DME/Height checks)
Listening to the ID beeps only tells you that the localizer is working. Nothing tells you that the glidepath is out. That is why you do GP checks and the final approach point. At almost 8 miles back and on the GP they should have been around 2800', not 900. Maybe if they hand flew the ILS they would have realized earlier that there was a problem because normally you can't hand fly a ILS that perfectly.
I agree that that was their major mistake. Not doing the glideslope interception check (DME/Altitude crosscheck) untill quite late in the approach (below 1000ft). I guess that's the main point of this video. It's one thing to know that you should complete checks for certain things. but to know why might just make it more compelling.
@NZtegmen, you're right. Although... Im not a pilot (ILS Tech), but in the past when I NOTAMed the ILS "un-monitored" it was because a communication line sending monitored signal back to the tower and maint was cut, hence ILS unmonitored. The actual ILS air borne signal was perfect. This was verified at the actual sites. His Glideslope was left radiating Hazardous Misleading Information HMI, a big no no in the FAA.
when you are decending at 800 feet per minute toward the ground with the landing gear down, flaps 30 selected, and the Autoland 3 green light on, with Glideslope and Localizer needles centred, GPWS will only say "500 400 300 200 100 50 40 30 20 10" not "Pull up Pull up". This is because it believes you are on decent profile and about to land on a runway, rather than about to slam into a hill.
Also note, the indications on the instruments were exactly the same as if one was on course to land on the runway. The problem was the radio transmitter was sending the wrong signals. GPWS can't tell the difference between being on course, and the equipment giving the on course signal in error.
GPWS also uses radar altimeter info to interpret rate of closure. Flap and gear will cancel some warnings but an abnormal closure rate with terrain will activate the "whoop whoop pull up" command as I found out once on approach to Terrace BC while in level flight at the MDA for that segment.
I've flown that approach. What a lovely approach. jk.
The VOR approach into Williams Lake will do the same as you cross the VOR. Add a couple hundred feet to the VOR crossing height will solve that problem.
Speaking as an electronics designer I'm amazed that the absence of the 90 and 150Hz modulations isn't detected and flagged as an error by the the ILS receiver(s). It would be trivially simple to do with modern electronics. I presume this must a 'hangover' from a very old design concept that hasn't been improved.
@pasoundman, speaking as ILS tech, the monitors are there to detect such absence. The tech obviously engaged the monitor bypass feature and readiated HMI and walked away from the system. This is something I would ONLY do if I completely NOTAM the GS out of service. Even then I would dummy load the air borne signal just in case. In the case where a normal signals loses its SBO (90 and 150) the transmitter would immediately shut itself off.
US approach charts have an altitude restriction on the chart & an altitude that you should be at when crossing the outer marker or Final Approach Fix to avoid false glideslope indications or errors of this nature. If you are at the designated crossing altitude & not at the marker or FAF you should not continue the approach. I got caught with a false glideslope in flight school forty years ago and got an unsat grade I try to always make that check, might forget once & a while but not often.
10 1/2 minute upload limit on Youtube, so I'v edited it down to what I felt rounded out the video as a "complete-sounding" production. Rest of it was just more detail on the ILS saftey systems and why they failed, plus a few other pointers. Full video is over 38 mins.
wow - very informative i'll keep that in mind if i ever encouter a similar situation (no relative movement of the glideslope indicator regardless of the VS on localizer.) The scary thing is that you could intercept the outermarker at the appropriate altitude and establish what you'd deem as an appropriate descent rate and believe that your just flying fantastically today. This is one case were complacency could kill. I'd like to see the whole sequence, any place to get it???
How do pilots maintain glide slope? do they use yokes or trim?
FSX09pilot 7 months ago in playlist ils landing
@FSX09pilot In this particular case they used the APP mode of the autopilot, obviously down to below 800ft as LAND3 was activated by the autopilot in the latter part of the decent. The autopilot would use Trim to adjust decent rate. If it was being flown manually, the pilot would use a combination of Yoke, Trim and Throttle to adjust decent rate and pitch.
musicalaviator 7 months ago
@musicalaviator thanks for the quick response
FSX09pilot 7 months ago
90 and 150 hootz
Kg277 7 months ago
I've seen someone tie the windsock to a rock on the ground so that the pilots think the wind is calm and land instead of diverting.
It happened in PNG, and yes it was a true story.
Avantime 2 years ago
Thank you very much for the video!!!!
pepefone 3 years ago
To whoever "Spam Marked" the spam... many thanks :)
musicalaviator 4 years ago
doesnt answer the question, as to why the crew placed total reliance on an ils dme approach when they knew it was un-monitored before they left the ground?
NZtegmen 4 years ago
So you suggest they should do what? a non-precision VOR approach even when theyre recieving Ident and 'on path and slope' indications with the Autopilot accepting land3? They were slightly suspicious of the ILS which is why they monitored the ident all the way down. *beeps in headset all approach.*ILS use would be normal here with 'caution' (ie monitoring DME and Ident and doing DME/Height checks)
musicalaviator 4 years ago
Listening to the ID beeps only tells you that the localizer is working. Nothing tells you that the glidepath is out. That is why you do GP checks and the final approach point. At almost 8 miles back and on the GP they should have been around 2800', not 900. Maybe if they hand flew the ILS they would have realized earlier that there was a problem because normally you can't hand fly a ILS that perfectly.
positrack70 4 years ago
I agree that that was their major mistake. Not doing the glideslope interception check (DME/Altitude crosscheck) untill quite late in the approach (below 1000ft). I guess that's the main point of this video. It's one thing to know that you should complete checks for certain things. but to know why might just make it more compelling.
musicalaviator 4 years ago
@NZtegmen, you're right. Although... Im not a pilot (ILS Tech), but in the past when I NOTAMed the ILS "un-monitored" it was because a communication line sending monitored signal back to the tower and maint was cut, hence ILS unmonitored. The actual ILS air borne signal was perfect. This was verified at the actual sites. His Glideslope was left radiating Hazardous Misleading Information HMI, a big no no in the FAA.
CoolassVibe 1 year ago
I don't get why the GPWS would not detect and alert the crew? Well spose this is a mountainous region?
Lew747 4 years ago
when you are decending at 800 feet per minute toward the ground with the landing gear down, flaps 30 selected, and the Autoland 3 green light on, with Glideslope and Localizer needles centred, GPWS will only say "500 400 300 200 100 50 40 30 20 10" not "Pull up Pull up". This is because it believes you are on decent profile and about to land on a runway, rather than about to slam into a hill.
musicalaviator 4 years ago
Also note, the indications on the instruments were exactly the same as if one was on course to land on the runway. The problem was the radio transmitter was sending the wrong signals. GPWS can't tell the difference between being on course, and the equipment giving the on course signal in error.
musicalaviator 4 years ago
GPWS also uses radar altimeter info to interpret rate of closure. Flap and gear will cancel some warnings but an abnormal closure rate with terrain will activate the "whoop whoop pull up" command as I found out once on approach to Terrace BC while in level flight at the MDA for that segment.
mvrrc 4 years ago
I've flown that approach. What a lovely approach. jk.
The VOR approach into Williams Lake will do the same as you cross the VOR. Add a couple hundred feet to the VOR crossing height will solve that problem.
positrack70 4 years ago
Speaking as an electronics designer I'm amazed that the absence of the 90 and 150Hz modulations isn't detected and flagged as an error by the the ILS receiver(s). It would be trivially simple to do with modern electronics. I presume this must a 'hangover' from a very old design concept that hasn't been improved.
pasoundman 4 years ago
Scrub that. I misunderstood the nature of the fault slightly on first viewing.
pasoundman 4 years ago
@pasoundman, speaking as ILS tech, the monitors are there to detect such absence. The tech obviously engaged the monitor bypass feature and readiated HMI and walked away from the system. This is something I would ONLY do if I completely NOTAM the GS out of service. Even then I would dummy load the air borne signal just in case. In the case where a normal signals loses its SBO (90 and 150) the transmitter would immediately shut itself off.
CoolassVibe 1 year ago
Love the accent :)
Rodnoneous45aylmore 4 years ago
Excellent video. There is some comical moments in it although its a very serious issue. For example (at about 04:10):
Narrator: "The first officer was surprised that the lights from an adjacent village were so close. He voiced his surprise."
First Officer: "Sh!t those lights are close".
Cracked me up yet doesn't detract from the quality of the lesson being learned. 5 stars from me.
Cheers.
DewedUpScope 5 years ago
This is great; thank you for posting.
Crashman2 5 years ago
US approach charts have an altitude restriction on the chart & an altitude that you should be at when crossing the outer marker or Final Approach Fix to avoid false glideslope indications or errors of this nature. If you are at the designated crossing altitude & not at the marker or FAF you should not continue the approach. I got caught with a false glideslope in flight school forty years ago and got an unsat grade I try to always make that check, might forget once & a while but not often.
BE36pilot 5 years ago
wheres the rest of it??
Joshoc 5 years ago
10 1/2 minute upload limit on Youtube, so I'v edited it down to what I felt rounded out the video as a "complete-sounding" production. Rest of it was just more detail on the ILS saftey systems and why they failed, plus a few other pointers. Full video is over 38 mins.
musicalaviator 5 years ago
wow - very informative i'll keep that in mind if i ever encouter a similar situation (no relative movement of the glideslope indicator regardless of the VS on localizer.) The scary thing is that you could intercept the outermarker at the appropriate altitude and establish what you'd deem as an appropriate descent rate and believe that your just flying fantastically today. This is one case were complacency could kill. I'd like to see the whole sequence, any place to get it???
iiifly 5 years ago