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FLEX Temp after engine start


Nicco54
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Just had the same after a cold & dark start. First time the FLEX temp was not accepted, tried it again with the same temp and then it got accepted. 

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9 hours ago, CRJay said:

Just had the same after a cold & dark start. First time the FLEX temp was not accepted, tried it again with the same temp and then it got accepted. 

I got rejected multiple times. End up taking off without flex.

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  • Deputy Sheriffs

The flex temperature entry only works if your thrust levers are in IDLE position once the engines have been started. Any other position it will not work. This is by design of the aircraft.

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2 hours ago, Secondator said:

The flex temperature entry only works if your thrust levers are in IDLE position once the engines have been started. Any other position it will not work. This is by design of the aircraft.


I actually tried changing the flex when I was stopped but it didn't let me.
I've looked through my rockwell collins CRJ700/900/1000 FMS operator's guide and can't find any mention of the levers having to be in idle though, and can remember changing the flex more than once in the real aircraft while taxiing. Can't remember if the captain had the levers in idle though. Can you please confirm this?

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  • Deputy Sheriffs

This is the information that's available on the FCOM

The assumed temperature for Flex power can only be entered when:

- The Thrust levers are in IDLE or SHUTOFF detents
- The airplane has been in a weight-on-wheels (WOW) configuration for at least one minute,
- The assumed temperature entered is greater than the actual OAT, and
- The airspeed is less than 65 knots.

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2 hours ago, Secondator said:

This is the information that's available on the FCOM

The assumed temperature for Flex power can only be entered when:

- The Thrust levers are in IDLE or SHUTOFF detents
- The airplane has been in a weight-on-wheels (WOW) configuration for at least one minute,
- The assumed temperature entered is greater than the actual OAT, and
- The airspeed is less than 65 knots.

 

Thanks

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Hello,

 

I have never been able to enter a flex temp. I've done everything listed and when I enter a temp (ex. 46) or any value for that matter, I always get 'invalid entry'. I have tried with all data entered into the FMS already, engines at idle / or at cutoff, aircraft loaded, parked and always the invalid entry comes up and the flex temp never allows me to enter it. What am I missing?

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42 minutes ago, FSHomeCockpit said:

Hello,

 

I have never been able to enter a flex temp. I've done everything listed and when I enter a temp (ex. 46) or any value for that matter, I always get 'invalid entry'. I have tried with all data entered into the FMS already, engines at idle / or at cutoff, aircraft loaded, parked and always the invalid entry comes up and the flex temp never allows me to enter it. What am I missing?

Flex Temp is NOT an arbitrary number like 46C (115F).  I use Flex all the time, but have never entered 46.  Here is an excerpt and an article on Flex Temp "

The flex thrust/assumed temperature method employs an alternate thrust setting that is applicable to the highest ambient temperature at which the airplane could meet performance requirements at its actual takeoff weight.

Flex thrust essentially takes advantage of the spread between the actual weight at the actual temperature and whatever the maximum temperature for that weight would be. Assume, for example, that we are preparing for takeoff from an airport with an outside air temperature (OAT) of 10 degrees C. Our runway analysis data show that the maximum takeoff weight at this temperature is 157,000 lb. But, because our aircraft weighs only 147,000 lb, we can move up the data columns until we find the maximum OAT for our actual weight, which is 35 degrees C."

 

https://flightsafety.org/asw-article/when-less-is-more/

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59 minutes ago, Crabby said:

Flex Temp is NOT an arbitrary number like 46C (115F).  I use Flex all the time, but have never entered 46.  Here is an excerpt and an article on Flex Temp "

The flex thrust/assumed temperature method employs an alternate thrust setting that is applicable to the highest ambient temperature at which the airplane could meet performance requirements at its actual takeoff weight.

Flex thrust essentially takes advantage of the spread between the actual weight at the actual temperature and whatever the maximum temperature for that weight would be. Assume, for example, that we are preparing for takeoff from an airport with an outside air temperature (OAT) of 10 degrees C. Our runway analysis data show that the maximum takeoff weight at this temperature is 157,000 lb. But, because our aircraft weighs only 147,000 lb, we can move up the data columns until we find the maximum OAT for our actual weight, which is 35 degrees C."

 

https://flightsafety.org/asw-article/when-less-is-more/

46 was the number given by the dude in his tutorials. I also know this number changes. I've followed those videos FMS data entries exactly as he does in the video and when he enters the flex temp it takes it. When I do the same steps as in the video and get to entering the flex temp. It gives me invalid entry. No matter the number. Every single time. Since release day.

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42 minutes ago, FSHomeCockpit said:

I just want to know if there are *required* fields that need to be filled in for flex temp to be accepted. As far as I can tell it's a semi-broken feature.. or at least for me completely broken

 

To my knowledge, you should be able to set the FLEX temp without filling in any other field. But in the real world, I always fill in the perf pages before setting any FLEX value as it makes more sense.

The computerized load sheet will be given to you by the coordinator, but he/she will give it to you right before you are ready to close the doors, therefore inserting your FLEX temp before receiving the final load sheet doesn’t make much sense seeing as things can change (last minute changes, discrepancies and so on).

 

I always insert the estimated ZFW which is given on the OFP or ask the coordinator for the latest estimated PAX and cargo numbers and insert them into the FMS. I then I calculate the FLEX for the runway in use but i don’t insert it yet, I just write it down on a piece of paper. Once I get the load sheet, I insert the load sheet ZFW and check that the FLEX that i had estimated was correct. If it is then I insert it into the FMS, if it’s not, I calculate it again.

Basically if your estimated ZFW was off by quite a bit, your max FLEX will change as well.

 

I hope this made sense :)

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18 minutes ago, Nicco54 said:

 

To my knowledge, you should be able to set the FLEX temp without filling in any other field. But in the real world, I always fill in the perf pages before setting any FLEX value as it makes more sense.

The computerized load sheet will be given to you by the coordinator, but he/she will give it to you right before you are ready to close the doors, therefore inserting your FLEX temp before receiving the final load sheet doesn’t make much sense seeing as things can change (last minute changes, discrepancies and so on).

 

I always insert the estimated ZFW which is given on the OFP or ask the coordinator for the latest estimated PAX and cargo numbers and insert them into the FMS. I then I calculate the FLEX for the runway in use but i don’t insert it yet, I just write it down on a piece of paper. Once I get the load sheet, I insert the load sheet ZFW and check that the FLEX that i had estimated was correct. If it is then I insert it into the FMS, if it’s not, I calculate it again.

Basically if your estimated ZFW was off by quite a bit, your max FLEX will change as well.

 

I hope this made sense :)

Yes it does thank you. So I'm not missing anything then. I input the same info but still can't get the flex temp to enter.... Very strange 

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5 minutes ago, FSHomeCockpit said:

Yes it does thank you. So I'm not missing anything then. I input the same info but still can't get the flex temp to enter.... Very strange 


At what airport were you trying to insert your FLEX temp? What were the weather conditions (temp and altimeter setting) ? And what FLEX temp did you try to insert?
 

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I've tried at every airport I've flown out of. Basically all over the US and Caribbean. All different types of weather. I tried flex temps of 25, 35, 40, 46, 50 depending on OAT or randomly just for the hell of it to see if I can get anything entered. None have ever been accepted. 

 

Tried entering flex temp while at the gate, engines idle or off with the thrust levers in the off detents. 

 

I always enter the perf init data first and setup the rest of the FMS before trying to enter a flex temp. 

 

The A320N and CJ4 don't have this issue. I can enter flex values for those aircraft just fine. Only this CRJ is an issue.

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9 minutes ago, FSHomeCockpit said:

I've tried at every airport I've flown out of. Basically all over the US and Caribbean. All different types of weather. I tried flex temps of 25, 35, 40, 46, 50 depending on OAT or randomly just for the hell of it to see if I can get anything entered. None have ever been accepted. 

 

Tried entering flex temp while at the gate, engines idle or off with the thrust levers in the off detents. 

 

I always enter the perf init data first and setup the rest of the FMS before trying to enter a flex temp. 

 

The A320N and CJ4 don't have this issue. I can enter flex values for those aircraft just fine. Only this CRJ is an issue.


That's odd. I guess the Devs will have to answer this one, sorry. Try uninstall it and do a fresh install though, maybe that'll help.

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11 hours ago, FSHomeCockpit said:

46 was the number given by the dude in his tutorials. I also know this number changes. I've followed those videos FMS data entries exactly as he does in the video and when he enters the flex temp it takes it. When I do the same steps as in the video and get to entering the flex temp. It gives me invalid entry. No matter the number. Every single time. Since release day.

46, if the Dude did it right and I have to assume he did, was the number he arrived at for THAT flight given the configuration he had at the time.  He took into account the aircraft weight, OAT, pressure altitude, and runway length.  he then determined that under his particular circumstances at that particular time and at that particular airport, he could take off with a flex of 46.  The whole point is is that it is not an arbitrary number given on a video or a forum.  It is calculated.  I will try some things later when I fly but I would hope that the system will reject a number that is out of the limits. 

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22 hours ago, FSHomeCockpit said:

I've tried at every airport I've flown out of. Basically all over the US and Caribbean. All different types of weather. I tried flex temps of 25, 35, 40, 46, 50 depending on OAT or randomly just for the hell of it to see if I can get anything entered. None have ever been accepted. 

 

Tried entering flex temp while at the gate, engines idle or off with the thrust levers in the off detents. 

 

I always enter the perf init data first and setup the rest of the FMS before trying to enter a flex temp. 

 

The A320N and CJ4 don't have this issue. I can enter flex values for those aircraft just fine. Only this CRJ is an issue.

I have not tried entering a FLEX temp in the sim with engines running, but I do a lot of test flying at an airport with an extremely long runway (KVCV), and have never had an issue with entering FLEX either before or after filling out the PERF INIT. I typically use 55. It is not necessary to suffix the temperature with the letter “C” (just in case you might be doing that). The only requirement is that the entered temperature must be higher than the current OAT.

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On 6/4/2021 at 4:16 PM, JRBarrett said:

I have not tried entering a FLEX temp in the sim with engines running, but I do a lot of test flying at an airport with an extremely long runway (KVCV), and have never had an issue with entering FLEX either before or after filling out the PERF INIT. I typically use 55. It is not necessary to suffix the temperature with the letter “C” (just in case you might be doing that). The only requirement is that the entered temperature must be higher than the current OAT.

 

If that 55 is in C, then that might be a new bug/error to put on the list. The CRJ is only rated for operation up to ISA+35C (so 50C) and as far as I know should not accept any FLX temps above 49 as there is no data for it. Happy to stand corrected though, perhaps there are some operators with extended hot & high flex tables, just not that I know of. But this limitation is one of the reasons why a whole bunch of flights got cancelled in Phoenix, AZ some years back.

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20 hours ago, CRJay said:

 

If that 55 is in C, then that might be a new bug/error to put on the list. The CRJ is only rated for operation up to ISA+35C (so 50C) and as far as I know should not accept any FLX temps above 49 as there is no data for it. Happy to stand corrected though, perhaps there are some operators with extended hot & high flex tables, just not that I know of. But this limitation is one of the reasons why a whole bunch of flights got cancelled in Phoenix, AZ some years back.

 

That’s what I thought as well but wasn’t 100% sure so didn’t want to comment. 
Our company FLEX tables only go to up to 50, therefore I’ve never inserted anything more than that value in real life.

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On 6/3/2021 at 6:12 PM, Crabby said:

46, if the Dude did it right and I have to assume he did, was the number he arrived at for THAT flight given the configuration he had at the time.  He took into account the aircraft weight, OAT, pressure altitude, and runway length.  he then determined that under his particular circumstances at that particular time and at that particular airport, he could take off with a flex of 46.  The whole point is is that it is not an arbitrary number given on a video or a forum.  It is calculated.  I will try some things later when I fly but I would hope that the system will reject a number that is out of the limits. 

The dude said in the tutorial that 46 was the correct number for most of the departures in this aircraft. Since it is not developed a flex calc yet, we should use 46. Always.

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8 hours ago, TomAce said:

The dude said in the tutorial that 46 was the correct number for most of the departures in this aircraft. Since it is not developed a flex calc yet, we should use 46. Always.

 

At a high elevation airport with high temps, a somewhat low QNH and a short runway you might not want to use FLEX 46 as you could run out of runway before lifting off... 
There’s no such thing as a correct FLEX for most departures. FLEX will vary due to takeoff weight, QNH, temperature, wind, airport elevation, and runway in use.

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28 minutes ago, Nicco54 said:

 

At a high elevation airport with high temps, a somewhat low QNH and a short runway you might not want to use FLEX 46 as you could run out of runway before lifting off... 
There’s no such thing as a correct FLEX for most departures. FLEX will vary due to takeoff weight, QNH, temperature, wind, airport elevation, and runway in use.

I agree, but 46 will get you airborne in most cases before you run out of runway. So therefore we should use 46 - until Aerosoft releases a calculator.

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On 6/8/2021 at 8:01 AM, TomAce said:

The dude said in the tutorial that 46 was the correct number for most of the departures in this aircraft. Since it is not developed a flex calc yet, we should use 46. Always.

I don't remember that being said.  However, you could learn how to do the calculation manually.  It is not a difficult one.

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On 6/8/2021 at 11:42 PM, TomAce said:

I agree, but 46 will get you airborne in most cases before you run out of runway. So therefore we should use 46 - until Aerosoft releases a calculator.

You should probably just use no flex as long as there is no calculator, as the EFB V-speeds will be incorrect for whatever FLEX you set.

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