Radio altitude

[Guest]

On the PDF and on the groun my Radio altimeter is always-6. Is this correct?Joao

[Guest WorkingStiff]

Yes its correct.

[Guest Ian_Riddell]

"On the PDF and on the groun my Radio altimeter is always -6. Is this correct?"Not always, Joao.I think I may have seen a different value to this... It depends on the weight of the aircraft.... and, of course, the type of aircraft. The 747-400, for example, is commonly -8 feet (Here's a diagram showing why....).http://www.ozemail.com.au/~iriddell/RadAlt2.gifCheers.Ian.

[Guest ilh]

Wow, quite a picture to illustrate the point!!!Lee Hetherington (KBOS) | [link:www.sls.lcs.mit.edu/ilh/fs/PICPOSKY2.zip|B762 PIC/POSKYv3 Merge] | [link:www.sls.lcs.mit.edu/ilh/fs/DFMS734.zip]B734 Dreamfleet/Microsoft Merge

[Guest]

It

[Guest Ian_Riddell]

"Wow, quite a picture to illustrate the point!!!"When you've been asked this question a dozen times (on three or four different forums), Lee... you find a picture is worth a thousand words :-lolCheers.Ian.P.S. I may have mentioned this before, but a 747 SP has the Radio Altimeter antennae located behind the main gear (In such cases, what do you think would happen to the readout? :-)).

[Guest]

Well, if the antenna was behind the mains, it should indicate a positive altitude of a few feet once the nose gear hits the pavement as the tail comes up after touchdown.Nice diagram, by the way...

[Guest]

I wonder what their radar altimeter read then:

[Guest ielchitz]

I'm thinking that in this case someone's RA reads "Time to start looking for another job".Ian E.

[Guest HPSOV]

Here is a totally useless fact for you...At some airport in Asia they use a tug that connects from behind the nosewheel, with the body of the tug being underneath the aircraft... below the Radio Altimiter antenna's. This will cause the RA's to give erroneous readings... someone said that this will lead to a NO LAND 3 display until the tug is removed... and truth in that Ian?(If thats too far into the books then dont worry!)

[Guest Ian_Riddell]

"At some airport in Asia they use a tug that connects from behind the nosewheel, with the body of the tug being underneath the aircraft... below the Radio Altimiter antenna's."Interesting... I wouldn't have thought there would have been a tug low enough, HP... at least not for a 767 (but then I don't see much action away from home base)." This will cause the RA's to give erroneous readings..."We used to have trouble with some of the older 747's which were sometimes parked over drainage grates during maintenance, giving false readings. If there was a height difference between the 3 RA systems, the instrument comparator circuits would trigger an alarm." ..... someone said that this will lead to a NO LAND 3 display until the tug is removed... and truth in that Ian?"The RA system can tolerate no signal return (as you would find above 2,500')... and a negative height of well under -6 feet, so I'm guessing that this is not the problem. Perhaps a similar thing to the 747 and the drainage grate may be happening with the 767 and the tug. Perhaps the comparator circuits in the A/P system sensed height variations and triggered a NO LAND 3 (say if the tug body was a strange shape, each RA system would be recording a different height). "(If thats too far into the books then dont worry!)"Actually, I'll be off work for a month (vacation time).....so don't expect anything too intelligent from me for the next few weeks ;-)Cheers.Ian.

[Guest]

P.S. I may have mentioned this before, but a 747 SP has the Radio Altimeter antennae located behind the main gear (In such cases, what do you think would happen to the readout? ). Depends... when it is not placed too far back it might just give something around zero, because of the compression of the gear. Groetjes, http://www.grillsportverein.de/smilies/con...doom/bounce.gifDiederik Krauwer - EHAM

[Guest Ian_Riddell]

Actually, I was hoping someone could tell me.... It's been so long since I've worked on an SP RA system, I can't remember what it was :-lolAll I recall was that it was different (At a guess, I think, perhaps somewhere between 0 and the normal value). I don't think it was positive. The antennae were only a few feet away from the body gear.Cheers.Ian.

[wchafe 0]

>Actually, I'll be off work for a month (vacation time).....so don't expect anything too intelligent from me for the next few weeks Oooh, what an easy target! If it was anyone but you Ian, I'd just have to bite. ;-)Regards,Wade

[Guest]

See, that's part of the "Bigger problem"...with our Protestant North American work ethic...with having demanding high stress jobs just so we can 'keep up' with the competition...most people get 2 weeks a year off work this side of the pond, some people are "lucky" and get 3 weeks off to start and maybe after 20 years + service they get a month or 5 weeks off. CRAP. I am not a lazy person, but I think we are getting a bum deal in general. Can anything be done, probably not, but at least be aware of the 'great' rip-off and try to understand how we all ended up getting the shaft and why it is contributing to the demise of our society and our so-called "higher standard of living" we once prided ourselves on.In Europe, the average vacation for a salaried job is anywhere from 4-6 weeks...to start...it goes up from there. Is Europe not competing or considered the 'lazy bum' of the world...hardly! My relatives in the UK often laugh in disgust at the measley amount of time off we are afforded in N. America, even with bigger companies in senior positions. Recently, France was criticised for having labour policies which dictated that companies could not lay off emloyees unless they could prove they were actually losing money, not just a shortfall to exceedingly high profit expecations. A good example of this is the banks here in Canada who made less money than they had hoped (did NOT lose money), so they laid off 1000's of employees because the profit was not quite high enough (2000-2001). Guess who is paying many of their "salaries" now...that's right, me and you...and the words banking and service do not go hand in hand nowadays..funny though, my average annual fees went up...hmmm. This is, as I understand it to be part of the reason, why France instituted some of the policies they did - to curb layoff's as a means to meeting profit objectives to keep the shareholders happy...at the expense of the tax payer/government.Another aspect of this complex and rather disturbing state of affairs...ever wonder why N. America has some of the highest per capita divorce, heart attack, suicide, and murder/going-postal-at-work rates in the world? We also supposedly have one of the highest standards of living in the world. Something is out of wack I would say, and it's more than the quality of the wine keeping the French healthy and happy in marriage and life in general. We (North America), much like the Japanese, have adopted a "LIVE TO WORK" mentality, giving up on the "WORK TO LIVE" mentality which seems to be alive and well outside of N. America. We used to have the right to 'life, liberty, freedom...', we traded that in for a mortgage and a 50 hour+ work week after the industrial revolution. Perhaps it has to do with the "pioneer" spirit in N. America; we work from sun up to sun down (or later) and we are proud of the work we do and do not dwell on the sacrifices...the family, the vacation/leisure time, the loss of health and overall happiness. Our concern with the bottom line and ruthless effeiciency, along with burying the competition has engulfed our lifestyle and taken away our leisure - our life, liberty, and certainly our freedom/free time. When people meet me and ask me "what do you do", I enjoy answering "I take my nephew out to the airport to go plane spotting, I love my girlfriend spend as much time as I can, I flightsim about 15+ hours per week, I see my parents when I can, and when I can't do any of those things, it's because I am working 40-50 hours per week to make sure the bills get paid". This throws people off as most assume what you "do" is what you "are". For me, this is most certainly not correct, I WORK TO LIVE, nothing is more important to me than leisure time - aka - time I can spend with family and freinds...because in my books, if you don't have the time to spend with family and freinds, then what is the point. People often scowl when I say this as it fly's in the face of the "career path" being the most important thing in the world for most people. We, in North America, do not enjoy the amount of time with family and freinds that other nations do. In fact, other nations have strong laws in place to guarantee leisure time. I know the laissez faire economists will not enjoy my diatribe, but things are flying out of wack and it is time we realized just how much of a bum-deal we have here.I am not a "pinko commie" (in the immortal words of Archie Bunker) but I think I have some ideas as to why N.America has such terrible rates of divorce, suicide, murder, etc...it is more than just the lack of vacation time, the unforgiving and unsympathetic nature of our system...time with family is also, for the most part, very limited and I am sure that is partly the cause of many associated problems. What's my point? Well I could go on, suffice to say we are getting a bum deal on this side of the pond and we need to be aware it is not "normal".I feel better now, a little bit anyhow. Many people will likely not agree with me, and they also enjoy working 24/7 to make a living and get ahead. Our system is sick and getting critical. People are stressed out and ###### most of the time, people can't have babies, the bills exceed the income, the interest is draining the savings, the boss is an #####, etc, etc, etc...take a ride on a busy highway, or hang out at the check in desk at an airport if you don't believe me. I am not saying that Europe has all the answers, but they certainly have a much healthier and happier society (look at the stats compared to US/Canada), their economies are not exactly hurting (at all), and they manage to accomplish all this with 4-8 weeks vacation and an average 30 hour work week. Wow. Anyone care to join the dicussion, perhaps a new thread can be made. It was Ian's "month off" that got me started on this...heheRob.