V2+15 Prior to Acceleration Alt - 737
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V2+15 Prior to Acceleration Alt - 737
Dear All,
In the NG Sim, Often I reach V2+15 before the Acceleration Altitude.
Procedure states to selelct N1, SPD UP before retracting Flaps for noise abatment.
Do you retract flaps based on V2+15 regardless of Altitude?
In the NG Sim, Often I reach V2+15 before the Acceleration Altitude.
Procedure states to selelct N1, SPD UP before retracting Flaps for noise abatment.
Do you retract flaps based on V2+15 regardless of Altitude?
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More than one path to a clean wing........
Typical pilot personalities gravitate to ONE answer, ONE CORRECT WAY; black/white right/wrong. The NG is flown by different crews in different ways all over the globe every minute of the day. Just ask the __________ (you fill in the nationality or airline) and they will tell you that they are the BEST.
In your original question you mentioned being in the NG sim. In a training environment the RIGHT answer is what the instructor evaluating/training says that it is (under most cases). Presumably based on whatever the company procedures are at that time.
Our polity is to verify a valid roll mode at 500’ (LNAV, HDG SEL – whatever) then at 1,000’ AGL we start accelerating and changing configuration. So, no (in our case) we would not be retracting flaps based on V2+15 regardless of altitude. For us being at the appropriate speed and altitude will come first (they are closely related) then we would be retracting flaps, rather than calling for flap retraction the moment V2+15 is achieved.
Certainly you are free to post your question here or anywhere else. This answer is going to be airline specific; I would ask the instructor that is training/evaluating you.
In your original question you mentioned being in the NG sim. In a training environment the RIGHT answer is what the instructor evaluating/training says that it is (under most cases). Presumably based on whatever the company procedures are at that time.
Our polity is to verify a valid roll mode at 500’ (LNAV, HDG SEL – whatever) then at 1,000’ AGL we start accelerating and changing configuration. So, no (in our case) we would not be retracting flaps based on V2+15 regardless of altitude. For us being at the appropriate speed and altitude will come first (they are closely related) then we would be retracting flaps, rather than calling for flap retraction the moment V2+15 is achieved.
Certainly you are free to post your question here or anywhere else. This answer is going to be airline specific; I would ask the instructor that is training/evaluating you.
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The above post is correct ..after rotation and following th FD's the plane will fly out at a speed around V2+15 - V2+20 you would fly this to the designated AA that your company SOP's will mention.
I wouldnt want to retract the flaps at 500ft.
I wouldnt want to retract the flaps at 500ft.
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Acceleration Altitude
Dear NorthBeach,
Many thanks for your reply.
Boeing FCOM's state that if V2+20 is exceeded prior to Acceleration Altitude(AA) then Flight Directors should be ignored (Pitch Up) - This would make more sense - trading of the excess speed to reach your AA sooner.
Have you ever come across this, it seems that the FMC Computed N1 value is always higher than required for initial climb at V2+ 20.
Many thanks for your reply.
Boeing FCOM's state that if V2+20 is exceeded prior to Acceleration Altitude(AA) then Flight Directors should be ignored (Pitch Up) - This would make more sense - trading of the excess speed to reach your AA sooner.
Have you ever come across this, it seems that the FMC Computed N1 value is always higher than required for initial climb at V2+ 20.
Last edited by Alltheway; 26th Feb 2010 at 16:07.
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Pitch + power = performance
The FMC computed N1 value is given to ensure minimum certification performance-should you lose an engine.
Pitch + Power = Performance
The N1 computed value is the power portion of the equation. The flight directors will command the pitch portion. What you actually get depends on where you stick the nose of the jet, and whether you have met the other parameters (like flap settings, gear position and correct data entry).
I’m with you, if I am above V2+20, I would pitch up (trade airspeed for altitude) just like you said; before cleaning up the wing.
It’s the airline’s company and jet; they pay me to show up and move the metal from point A to point B safely and in compliance. I’ll fly it the way they pay me to fly it (unless there is a really good reason to disregard their guidance).
The fact that you are thinking and asking the questions shows you have your head in the process. That mind set and hard work will pay great dividends when you go for your command.
Happy flying!!
Respectfully,
Northbeach
Pitch + Power = Performance
The N1 computed value is the power portion of the equation. The flight directors will command the pitch portion. What you actually get depends on where you stick the nose of the jet, and whether you have met the other parameters (like flap settings, gear position and correct data entry).
I’m with you, if I am above V2+20, I would pitch up (trade airspeed for altitude) just like you said; before cleaning up the wing.
It’s the airline’s company and jet; they pay me to show up and move the metal from point A to point B safely and in compliance. I’ll fly it the way they pay me to fly it (unless there is a really good reason to disregard their guidance).
The fact that you are thinking and asking the questions shows you have your head in the process. That mind set and hard work will pay great dividends when you go for your command.
Happy flying!!
Respectfully,
Northbeach
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I’m with you, if I am above V2+20, I would pitch up (trade airspeed for altitude) just like you said; before cleaning up the wing.
Think...AA DC10 at ORD where the engine fell off.
Keep the blue side up, absolutely.
; exactly your words were seen here about a year ago.... guessing he is preparing for another type 
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More than One way to clean a Wing
Northbeach,
Thanks for the detailed and constructive reply.
Its the first time i've questioned following the F/D's but Boeing SOP's also state to ignore.
I guess its Pilot call whether you wish to have Altitude or Airspeed, personally below 1500 its certainly altitude I would also pitch for as V2 is also our margin for Single Engine.
Are there other situations you would ignore Flight Directors?
Thanks for the detailed and constructive reply.
Its the first time i've questioned following the F/D's but Boeing SOP's also state to ignore.
I guess its Pilot call whether you wish to have Altitude or Airspeed, personally below 1500 its certainly altitude I would also pitch for as V2 is also our margin for Single Engine.
Are there other situations you would ignore Flight Directors?
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Flying through the Flight Director-usually there is a better way...
I have been on the NG for only 2 years now (after 12 years on the previous type). Most of the time when I thought the “jet screwed up” it was in fact my error: programming error, incomplete/inaccurate system knowledge and other such variations of getting it wrong. As a policy I would not recommend you “ignore Flight Directors” (also called flying through the flight directors). Reminder: I don’t set “policy” for you or your company-or anybody else for that matter. I have much confidence in the NG; if the flight director isn’t providing the guidance I want I expect the error to rest with me. “Something isn’t right” feeling needs to be solved to the pilot’s satisfaction rather than the automation ignored (outside of well understood scenarios such as being momentarily above V2+15 during takeoff).
If your flight director is not giving you what you want you have at least two options. First of all, instead of ignoring your flight directors, I would recommend simply turning them off and fly the airplane without them. After all how many years did you spend driving around in multi-engine aircraft IFR without a flight director or autopilot? Some pilots may not have this experience to fall back on and may look at a flight director failure as an emergency. It shouldn’t be but that is a different discussion.
Your second option is to figure out how to get the flight director to give you the guidance you want. Automation is there to help you; if it isn’t helping turn it off, have your flying partner set you up for success.
I hope you are enjoying your time on the NG, and that your upgrade opportunity comes sooner rather than later.
If your flight director is not giving you what you want you have at least two options. First of all, instead of ignoring your flight directors, I would recommend simply turning them off and fly the airplane without them. After all how many years did you spend driving around in multi-engine aircraft IFR without a flight director or autopilot? Some pilots may not have this experience to fall back on and may look at a flight director failure as an emergency. It shouldn’t be but that is a different discussion.
Your second option is to figure out how to get the flight director to give you the guidance you want. Automation is there to help you; if it isn’t helping turn it off, have your flying partner set you up for success.
I hope you are enjoying your time on the NG, and that your upgrade opportunity comes sooner rather than later.
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QUOTE:If your flight director is not giving you what you want you have at least two options. First of all, instead of ignoring your flight directors, I would recommend simply turning them off and fly the airplane without them. UNQUOTE
I would highly suggest keeping the flight directors ON and monitor the Autopilot to be sure it is not deviating from relatively standard maneuvers. For example high pitch during initial take off.( i believe 25 Degrees pith up is considered an UPSET,could happen if you takeoff on a ferry flight with full rated thrust).Some airlines may restrict your pitch to 20 degrees.
In that case i would limit the pitch manually but keep the FD engaged,the pitch will rejoin the FDs commands after.
Under rotation on lift off will increase your target speed (V2+15) and above V2 +25 you will be out of Noise abatement and also lower than you should for terrain clearance..So i would pitch up above flight directors(within Boeing and company limit) to regain the proper airspeed but making sure i set the correct pitch for the phase of flight before your speed goes below your target..or check closely your FD pitch command and notice and follow its downward trend until the proper pitch/airspeed is regained.
I often during nice clear days flew and offered to fly raw data (no FD /AT/AP) departures(initial vor radial intercept) until the aircraft reached 10000 feet.
However this was briefed as it was non standard procedures and you have to make sure your colleague is familiar with different pitch attitudes and raw data navigation along with specific task sharing.(PM would set all courses,reengage FD.AT..) when briefed..
PS:if you switch FDs OFF with autopilot engaged nothing will happen, the AP will still fly as directed from MCP
CMFVIDINI:
If you stay between V2 and V2+25 you are ok for noise,
if you maintain less than V2+15 you will be limited to 15 degr bank(ie turn before acceleration altitude).
To answer your question, your SOP say to (SPD UP or BuG UP) to give command to your FD to set Pitch for acceleration.which will avoid pilots retracting flaps at V2+15 and forgetting to accelerate towards the next flap maneuvering speed.
I always wait for pitch to be set for acceleration before I start retracting the flaps(MINIMUM V2+15).
You keep your target speed(V2 to V2+20) until reaching your acceleration altitude(based on Performance data/company SOPs/Noise Abatement).
I would highly suggest keeping the flight directors ON and monitor the Autopilot to be sure it is not deviating from relatively standard maneuvers. For example high pitch during initial take off.( i believe 25 Degrees pith up is considered an UPSET,could happen if you takeoff on a ferry flight with full rated thrust).Some airlines may restrict your pitch to 20 degrees.
In that case i would limit the pitch manually but keep the FD engaged,the pitch will rejoin the FDs commands after.
Under rotation on lift off will increase your target speed (V2+15) and above V2 +25 you will be out of Noise abatement and also lower than you should for terrain clearance..So i would pitch up above flight directors(within Boeing and company limit) to regain the proper airspeed but making sure i set the correct pitch for the phase of flight before your speed goes below your target..or check closely your FD pitch command and notice and follow its downward trend until the proper pitch/airspeed is regained.
I often during nice clear days flew and offered to fly raw data (no FD /AT/AP) departures(initial vor radial intercept) until the aircraft reached 10000 feet.
However this was briefed as it was non standard procedures and you have to make sure your colleague is familiar with different pitch attitudes and raw data navigation along with specific task sharing.(PM would set all courses,reengage FD.AT..) when briefed..
PS:if you switch FDs OFF with autopilot engaged nothing will happen, the AP will still fly as directed from MCP
CMFVIDINI:
If you stay between V2 and V2+25 you are ok for noise,
if you maintain less than V2+15 you will be limited to 15 degr bank(ie turn before acceleration altitude).
To answer your question, your SOP say to (SPD UP or BuG UP) to give command to your FD to set Pitch for acceleration.which will avoid pilots retracting flaps at V2+15 and forgetting to accelerate towards the next flap maneuvering speed.
I always wait for pitch to be set for acceleration before I start retracting the flaps(MINIMUM V2+15).
You keep your target speed(V2 to V2+20) until reaching your acceleration altitude(based on Performance data/company SOPs/Noise Abatement).
Last edited by skyeuropecapt; 2nd Mar 2010 at 10:22.
