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Dumb question?

Old 28th Mar 2009, 09:50
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Dumb question?

This one has been bugging me for a while. I should have had it answered ages before this but...well...I watch too much Air Crash Investigation and like to have the answers so I sound clever.

When you call ATC after takeoff, and give them your passing altitude, I have always assumed it was because ATC would then compare your verbal readout with the transponder readout they saw on screen. However, if your pitots/statics are blocked or faulty, then whatever you are reading will be the same as what the transponder altitude reporting gives, no? In which case, what exactly is ATC checking?

Birky
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Old 28th Mar 2009, 09:57
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I can't talk about pitot tubes, etc., but when a pilot passes his altitude on take-off ATC is verifying the altitude readout on radar against what he has reported. Without that verification, ATC cannot employ the altitude information for separation purposes.
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Old 28th Mar 2009, 15:07
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Telling your altitude/level upon calling ATC initially, is for them to compare your report with their readout.
That is since... 40 years ago, and my explanation dates from the same era...
xxx
Nowadays, when tower would transfer me to departure frequency, my call would be -
"Departure, flight XXX out of two thousand climbing to fife zero, good evening"...
That tells them I am vacating 2000 ft, and that they can clear other plane to that altitude.
And it implies that I request higher level... and a more direct routing if available.
These ATC guys know all that. They are "pros" as well.
As simple as that.
xxx

Happy contrails
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Old 29th Mar 2009, 13:05
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#departure,out of 2 000 ,climbing to fife zero,good evening#

OUCHHHHH,thats painful to my ears...

climbing to fife zero? you meant climbing to flight Level fife zero OR climbing 250?? in europe stating departure SID is a requirement for reasons you can all find on the UK CAA website.

and i am not going to go into discussing pilots calling #airborne# as their initial contact...
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Old 29th Mar 2009, 17:51
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Is calling airborne on tower freq a requirement in low vis ops.
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Old 29th Mar 2009, 17:51
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Dear Boingboingdriver -
xxx
Sorry for your ears.
I am one of these foreign crews who seldom operated to UK/CAA FIRs.
My airspace, lately, was South America, North America, Spain and Italy...
Even using Spanish dialect for R/T where/when suitable.
Or other languages even - Portuguese in Brazil, or French in Africa.
I am certain your linguistic abilities exceed mine...
Bless my retirement - you no longer risk a midair with my rocking chair.
And stop forcing captains to resort to solo when with you as F/O.
xxx

Happy contrails
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Old 29th Mar 2009, 18:42
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Actually, stating the departure SID is not a requirement in europe. It is just a requirement on that little island west of europe.
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Old 30th Mar 2009, 09:30
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Actually, stating the departure SID is not a requirement in europe. It is just a requirement on that little island west of europe.
Indeed so, and a few on that small island apparently assume otherwise.
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Old 30th Mar 2009, 12:40
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Dear all,

I am indeed following the UK phraseology.The reasons to state the departure flown on initial contact may save your skinny butt one day and can find some examples on the uk caa website under level bust;-)

After a quick search on google i found this website: SkyBrary containing ICAO recommended phraseology by EURO CONTROL...page 11.
You will see stating departure is recommended..

And calling airborne during lowvis ...there are no differences in comms whether low vis or cavok.
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Old 30th Mar 2009, 12:50
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Yes, it's a good idea because, amazingly enough, pilots do get the SID wrong sometimes. I saw a few at Heathrow who should have turned right but turned left instead... Great fun.
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Old 30th Mar 2009, 13:13
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It also allows the controller to spot the pilot error by crosschecking given sid versus climbing level and therefore to re clear the pilots accordingly. ..avoiding dangerous level busts or as mentioned off tracks...

I rest my case:-)
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Old 30th Mar 2009, 13:33
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I think ye all are missing Birky's point. He says that if there is a fault with the altimeter then wouldn't the transponder also have the error, hence ATC see's and hears the same error.
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Old 30th Mar 2009, 13:55
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If you lose function of all pitots/ statics sources (including auxiliary/alternates)which is not highly probable,unless you have multiple bird strikes while flying through hail and some nasty mean mechanic taped your static ports after you finished your walk around.. that means your only reference for speed would be pitch/thrust settings (IRS is giving tas)and for altitude...maybe your RA?so below 2500 feet ull get some to look for..

ATC will get the info your transponder is giving them from your selected altimeter data..so only thing they could do is give you vectors to low terrain if possible in VFR conditions..

Please take this with pinch of salt,not an engineer here...just first thoughts of a pilot.
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Old 30th Mar 2009, 16:32
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SAT could also give you a very rough idea of alt
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Old 30th Mar 2009, 18:49
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Survival

With Pitot- Static erroneous information, a last ditch help is the old simple Outside Air Temperture Gauge. If it remains about the same then you are roughly level, if it is reducing you would be gaining height and if it is increasing you are on the way down.

It has worked in the past!

Tmb
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Old 30th Mar 2009, 20:22
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Just to ask the question again!!!

Is calling airborne on tower freq a requirement in low vis ops?

I have flown for airlines that do and airlines that don't, my guess is you don't but with the wealth of experience on here with guys like Heathrow Director its worth an ask.

3REDS
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Old 30th Mar 2009, 23:55
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using OAT?maybe if there is no temperature inversion

requirement of calling 'airborne' during low vis? NO!!!!! unless you wanna be greeted with 'congratulations' by ATC
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Old 31st Mar 2009, 06:33
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Dumb Question

Thanks all for your replies. I'm glad one or two of you have at least confirmed what I was worried about; namely, that the transponder info is only as good as your instrument info, and that if you do have a static/pitot fault then ATC are going to be just as mis-informed as you are.

I guess if you were caught in the same situation as the Peruvian 757 was, you would whip out the QRH and choose the appropriate thrust setting and attitude for flight. Those guys got the stick shaker and yet chose to believe that they were still too fast. Whenever I watch that programme I always wonder why they didn't trust it.

Then again, I suppose we can all be Monday morning quarterbacks.

Thanks again,

Birky
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Old 31st Mar 2009, 11:43
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The requirement is to call the exact altitude/level passing, [eg. 3,800'] without rounding off [eg. 4,000'], . . . to verify only that your mode-c, pressure altitude function, is exactly reporting your indicated altitude. It's not to verify your true [actual] altitude, or whether your altitude is erroneously affected by CADC failure or other external anomalies such as blocked pitot tubes . . .
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Old 31st Mar 2009, 13:08
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requirement of calling 'airborne' during low vis? NO!!!!! unless you wanna be greeted with 'congratulations' by ATC
I fly for a large UK regional airline and there are plenty of airfields where ATC request you call airborne with tower during low viz.
Infact with my low ATC knowledge, I thought this was standard practice so the tower could confirm runway occupancy when they cant see the tarmac

I think the word 'standard' should be removed for the aviation dictionary!
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