Vref question
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Vref question
I have a question regarding the Vref speed that is set into the MCP during the landing. If your charts (and the FMC) tell you that for a flap 30 landing your Vref speed is 135, is this the speed you dial into the speed window on the MCP or is it Vref+5? Also, is the Vref speed and the flap 30 speed the same thing or no?
Cheers!
Cheers!
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Have we left a vital piece of information out? On some airlines and some types, one bugs Vref and flies to a cursor which may be set on Vref+5 or more depending on wind state, but it depends on airline procedures which should be followed, not personal preference. This is recommended usually when an autothrottle references the curser speed.
Perhaps a word or two of what basis and where your question comes from may be appropriate?
Perhaps a word or two of what basis and where your question comes from may be appropriate?
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Notso,
I am reading manuals and watching aviation videos to learn more about flying so that I can enter (hopefully) the aviation profession myself one day. The unfortunate thing about the manuals and videos is that they give you many pieces of information but don't always explain how they are meshed together.
For example, they discuss Vref speeds on the approach and I see them set their bugs (737-400) and the flight crew talk about the landing being a flap 30 landing and the Vref speed is 135. However, the captain also states the Vref+5 speed and I was wondering if this was what is dialed into the MCP's speed window.
I am only looking for clarification so that I can undertand some procedures better.
Cheers
I am reading manuals and watching aviation videos to learn more about flying so that I can enter (hopefully) the aviation profession myself one day. The unfortunate thing about the manuals and videos is that they give you many pieces of information but don't always explain how they are meshed together.
For example, they discuss Vref speeds on the approach and I see them set their bugs (737-400) and the flight crew talk about the landing being a flap 30 landing and the Vref speed is 135. However, the captain also states the Vref+5 speed and I was wondering if this was what is dialed into the MCP's speed window.
I am only looking for clarification so that I can undertand some procedures better.
Cheers
Per Ardua ad Astraeus
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xfeed - on 737 it is Vref that is set on the ASI, and the 'plus' bit in the MCP, the 'plus' being dependent on several things, such as wind and airframe icing to name two, not forgetting a bit for granny
The 'plus' bit is flown on the approach and should bled off to cross the threshold at Vref in nice conditions. Never normally lower than +5.
The 'plus' bit is flown on the approach and should bled off to cross the threshold at Vref in nice conditions. Never normally lower than +5.
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Just to make it clear- this may apply to 747 more than 737 which for me is now over 7 years out of date. You set an external bug on the ASI to Vref. On the MCP, you set a speed which is usually Vref+5 and that moves a cursor on the ASI, and it also controls the autothrottle to fly at that speed. On the current generation 747, you set the weight into a computer and that gives you a bug speed automatically (Vref)on the ASI. You still fly to a cursor controlled from the MCP which controls the autothrottle, and this is usually set after final flap to Vref+5 or higher if windshear conditions are present or certain failures are present.
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Thanks lads! I appreciate the very helpful information.
Notso,
In future I will try to preface my questions with the reason I am asking. Rest assured that all of my questions stem from an interest in aviation and the more I read or watch on video the more I learn but also the more questions I will have. I would change my profile to tell those interested that I am 21 years old and am hoping for a career in the profession but I can not figure out how to edit my profile.
Cheers!
Notso,
In future I will try to preface my questions with the reason I am asking. Rest assured that all of my questions stem from an interest in aviation and the more I read or watch on video the more I learn but also the more questions I will have. I would change my profile to tell those interested that I am 21 years old and am hoping for a career in the profession but I can not figure out how to edit my profile.
Cheers!
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You're welcome. It can be difficult answering sometimes when you don't know the level of experience (if any) of the other party. You used the language, yet didn't specify a type. Airliners go from WW2 style basic instruments to B777 style electronics, and by the look of it, bizjet avionics which are even more advanced, so type information is a must.
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I think a lot of other profiles need modifying. I get the impression there are a lot of kiddie flightsimmers here pretending they are ATPLs with various jet ratings! Just had one who reckoned he was All 737 & 310!
I might be one myself! I think the Flight Manager thinks I am one!
I might be one myself! I think the Flight Manager thinks I am one!
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XFeed
Our company SOP'S are:
set two of the white airspeed bugs (on the outside of the ASI) to VREF 30.
Then set the command airspeed bug (which is controlled by the speed dial on MCP) to the wind corrected speed.
Wind correction being Half the wind speed plus all the gust upto max 20kts, min of 5 kts
eg. Wind 260/14 gusting 23, Vref 130
Set two white bugs on vref 130kts and set the command bug to 146kts (half wind 7 kts gust is 9kts = 16 + vref 130)
Hope that makes sense.
Our company SOP'S are:
set two of the white airspeed bugs (on the outside of the ASI) to VREF 30.
Then set the command airspeed bug (which is controlled by the speed dial on MCP) to the wind corrected speed.
Wind correction being Half the wind speed plus all the gust upto max 20kts, min of 5 kts
eg. Wind 260/14 gusting 23, Vref 130
Set two white bugs on vref 130kts and set the command bug to 146kts (half wind 7 kts gust is 9kts = 16 + vref 130)
Hope that makes sense.
Buttonpusher
On our 757/767s we use a bug for Vref, and set the salmon bug (MCP) to Vref+5. or additive for gusty conditions (half of the steady and all of the gust) up to Vref+20. If we use the autothrottles we are not supposed to put the additive on as the autothrottles will "supposedly" compensate for gusts, however personally I have never trusted the a/t during gusty approaches, they seem too react too slowly for my liking. the other bugs go to Vref+40 and +80 for go-around flap retraction speeds....just my 2 cents worth..
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Thanks to everyone for their 'tuppance' worth. I appreciate the great information.
Notso,
Just out of curiosity why does it matter which plane you are flying when setting the Vref? You, it seems, fly the 744 and others who responded fly 737 or 757/767. It appears the information is the same across the board. Maybe I am missing something here so I would appreciate it if you could shed light upon your statement:
"Have we left a vital piece of information out? Like confirming type maybe? Perhaps even a clue in your profile as to what type you fly might help?"
Thanks again lads!
Notso,
Just out of curiosity why does it matter which plane you are flying when setting the Vref? You, it seems, fly the 744 and others who responded fly 737 or 757/767. It appears the information is the same across the board. Maybe I am missing something here so I would appreciate it if you could shed light upon your statement:
"Have we left a vital piece of information out? Like confirming type maybe? Perhaps even a clue in your profile as to what type you fly might help?"
Thanks again lads!
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Different airlines have different procedures, even for the same aeroplanes. It seems airline Technical departments can't wait to put their individual 'stamp' on operating procedures for a type when they enter service!
It does matter what type you talk about. The actual speed you want to fly at will usually be determined by the autothrottle controlling internal curser set from the MCP. But you still need the actual Vref displayed- done automatically on the 747 and by a bug on some models 737. Referenced on that, you need flap extension speeds displayed- bugs on early models and automatically displayed on later models. Operators can't even agree standard landing flap settings for the same type!
It does matter what type you talk about. The actual speed you want to fly at will usually be determined by the autothrottle controlling internal curser set from the MCP. But you still need the actual Vref displayed- done automatically on the 747 and by a bug on some models 737. Referenced on that, you need flap extension speeds displayed- bugs on early models and automatically displayed on later models. Operators can't even agree standard landing flap settings for the same type!
