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I'm pretty sure the ILS has been at the doctor's recently.
I have the July/10 ILS 30 with a 3.33 GP and an IF 8.7 from the field (and a spot height around 800' above the field) to the left of c/line......:eek:.). There is an OM at 2nm with a 754' ATE min crossing and a platform of 2800' ATE and descent at around 7nm from t/down.. |
BOAC
I mean I had an event when the G/S was erroneously too low. And that there are not false glideslopes below the nominal one. One thing is an antenna or whatever that is transmitting incorrectly and another is the sidelobes of the beam that produce false glideslopes. These are a 6, 9, 12 deg, etc, if I'm not wrong |
These are a 6, 9, 12 deg, etc, if I'm not wrong If 11.5 NM out and @530 feet they may have catched a slope well below 3 degrees. Anyone who is in the mood can figure it out.... BTW, sidelobs are not unusual for GS signals..... |
too low!
This is all about airmanship. That certain quality that cant be assessed or monitored. Call it what you will, hairs on the back of the neck, a third sense that all is not well. Long may it last.
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Somebody tell me again about those pilotless aircraft in our future....
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BOAC
which is why the plane shouldn't have been that low...wait till the outer marker confirms crossing altitude before you start down below the OM alt |
The problem may not be false glideslopes "below" the 3-deg one but of a failed glideslope, period, in which the indication centers and remains centered regardless of actual position.
Psychologically therefore, any and all effort to "maintain the glideslope" (high rate of descent, zero rate of descent, etc) is "rewarded", if the pilot isn't cross-checking the crossing altitudes and the DME as ssr has now twice pointed out. The A320 has a superb ND display which should show the position of everything, like the LOM, the airport and so on. It is hard to imagine how such data can be ignored or just not seen in favour of following either a lobe or a failed glideslope, but it has happened and will continue to happen unless cross-checks are done. It occurred at Apia, at Irkutsk, and I've seen it, recently, elsewhere. Astonishing, given detailed map displays and all, but there it is. |
Indeed - yet another 'WHAT??!!! Too many these days.
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Landing to the south at DFW in an MD80 one day with 1000 and 3 we were cleared for the ILS and the FO started a steep descent exceeding 1,000 FPM. The glide slope was pegged full down and we were in the clouds. Looking at the DME at the runway end and our altitude knew we were not high so told him to level off, the glide slope was wrong. 20 seconds later the glide slope snapped to showing us low.
I advised the tower of what happened and they said we don't have to protect the glide slope if the weather is better than 700 and 2. I said we were coupled so does that mean in the future we should only do the localizer approach since the glide slope can't be trusted? He said an aircraft crossed the ILS protected area because of the adequate weather. We didn't get below 1500 ft but it made me closely monitor what the ILS is telling you and if it is real or not. |
BOAC, re, "Indeed - yet another 'WHAT??!!! Too many these days."
And it's not newbies, magenta-liners, innocents (like Bonin & Shaw, et al) who are doing this. This is Guam, Busan, Charlotte NC, Smolensk, Crossair...all CFITs due to total absence of "checking six"..."where are we, what's my required altitude and when can I go down further?" It's just three components - slope, distance and height and they MUST agree, from intercept to touchdown. And not one crew member in any of these accidents called for a go-around until it was too late. Why? Why especially, are First Officers so damn reluctant to speak up? CRM is thirty years old. |
I always thought that beyond 12NM intercepting the GP (not the LOC) was pretty much a no-no - 'tis outside the operating parameters of the installation ... ?
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bubbers 44 demonstrated what piloting is all about...always use multiple sources of information to confirm, confirm, confirm.
One time while instructing in a piper turbo arrow (over 30 years ago), a student selected the VOR for an airport instead of the ILS. He didn't identify...but the course indicator was on course and the GS was centered, the flag sticking out of the way. (VMC ) so he started down on glideslope (even though he was not on the ILS). IT was perfect...500 fpm, tracking the VOR like a champ...I took his hood off and said: you got lucky, otherwise you would be dead...turned up the volume and made sure he knew the difference between the ILS ID and the VOR ID. |
A little more than that at 1312 feet and that would be a perfectly normal platform HEIGHT of 400 meters in Russia, but not at 14 miles out.
Glideslopes are often 2.7 degrees there as well. I haven't yet seen the appropriate chart though. |
The always on glideslope failure would be much more aparent if flying manually. Any pilot would quickly realise that the G/S is centerede no matter what. With AP, however, it will be more difficult.
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Originally Posted by Grum
Glideslopes are often 2.7 degrees there as well. I haven't yet seen the appropriate chart though.
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The always on glideslope failure would be much more aparent if flying manually. Any pilot would quickly realise that the G/S is centerede no matter what. With AP, however, it will be more difficult. The lesson is, 1) it happens, and, 2) you cannot say to whom it will occur. Everyone one of us who fly knows how to cross-check altitudes and distances while descending, and why. What we all think (and know) what should have happened, does not explain people's behaviour. Preparation, a thorough approach briefing with a solid knowledge of SOPs and PF/PM duties and situational awareness through a cultured airmanship are significant preventative, error-trapping measures, as demonstrated by the Air New Zealand B767 crew at Apia. But it can happen to anyone. There is no such thing as a "bad apple". The "other guy" is us, on any one day. |
There is no such thing as a "bad apple". The "other guy" is us, on any one day. Maybe the airport DME was u/s, GP u/s whatever, but as said, with all the 'kit', including a WTFAI map in front of us..........................???? Would this a/c have TAWS with a complete database? That should have started shouting as they penetrated the terrain floor. Perhaps that is why they went round, although I would have thought the TF was well before 530'ATE at 11 miles? The dangerous one is a GP fail 'on the slope' - there is a big clue if it is actually u/s earlier - the GP needle is 'centered' from or before LOC intercept. |
I don't know how they can do this, maybe maintenance, but flying into Burbank one day in VMC conditions the glideslope was perfectly centered. It didn't matter if you were high or low. The ATIS said glide slope was unusable but it didn't help the airliner behind us who got a low altitude alert from tower and said we are right on glide slope. Some days you can't trust anything.
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Bubbers44, I'm not sure I understand your confusion. ILS GS on ATIS as unusable and yet you watched it and presumably went low and high deliberately to see how it reacted (with or without a failure indication?), tower said you were on the correct approach path The guy behind you presumably flying in VMC couldn't maintain a constant approach to the runway are you saying that he too was using an unusable GS? Why would either of you want to do what you apparently did? What is it you can't trust the ATIS or the crew?
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Indeed - yet another 'WHAT??!!! Too many these days. Like Pan Am 806 in 1974 ? or 812 in the same year ? EAL 401 in 72 ? Approach phase accidents Last updated: 19 July 2012 Statistical information regarding the Approach flight phase. The number of fatal hull-loss accidents and fatalities per year is given. The figures include corporate jet and military transport accidents. Year Accidents Casualties 2012 4 148 2011 11 230 2010 9 327 2009 8 231 2008 10 208 2007 3 103 2006 4 136 2005 8 114 2004 10 106 2003 9 336 2002 17 589 2001 12 231 2000 12 434 1999 11 127 1998 18 581 1997 16 726 1996 21 540 1995 22 550 1994 17 701 1993 14 215 1992 22 900 1991 13 498 1990 15 417 1989 22 785 1988 30 722 1987 18 402 1986 22 437 1985 11 359 1984 8 134 1983 14 582 1982 9 412 1981 12 187 1980 14 598 1979 22 312 1978 17 546 1977 22 512 1976 16 706 1975 19 625 1974 22 775 1973 28 887 1972 26 1058 1971 18 624 1970 20 305 Given the numbers in 2012 vs. say, 1972, methinks the old eagles had more problems than the newbies....(granted, the equipment has moved on, but...) There is no such thing as a "bad apple". The "other guy" is us, on any one day. |
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