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Michele Benedetti

PFPX Concorde Profiles - Fuel Planning Issue

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Michele Benedetti

Hi! I've been trying for some time now to plan my Concorde using the PFPX Concorde profiles that @Fraser Gale brillianlty developed. Howeve, using the custom airframes, fuel policy and climb/descent procedures included with the profiles, I get very very strange fuel planning figures, here are some screenshots and some .txt s:

Example 1: EGLL-KJFK, live active sky weather, 100 passengers

Cattura.thumb.PNG.07bf28249835cff44aa60a85c2d220f3.PNGCattura1.thumb.PNG.8b827b73504106f5a0e04488e9fef3f7.PNG

Example 2: EGLL-TBPB, active sky live weather, 88 passengers

Cattura3.thumb.PNG.21ae2f8db6ce84659dc14c268b225b55.PNGCattura4.thumb.PNG.91244236aecab73ab033311aba8cc467.PNG

Here are the OFP's:

BAW001 EGLL-KJFK (31-May-2020) #1.txt

BAW272 EGLL-TBPB (31-May-2020) #1.txt

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Ray Proudfoot

One thing you should change is Cruise Altitude / Step Climb. Change to Max and Zero. I do that for 737 flights.

Oh, and remove cargo figures. Those should help.

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Fraser Gale

There is something very strange going on with your PFPX setup @Michele Benedetti and I'm not sure what.  I used all the same entries as you for EGLL - KJFK and got a release fuel of 91,181kg.  I did this with no weather because I let my subscription lapse.  

The points that Ray mentioned shouldn't make any difference hence I didn't select those and I added the amount of cargo you did. The one inaccuracy with my profiles is the cruise altitudes - PFPX can't understand cruise climb so ignore any flight levels it calculates. 

Can you try without using active sky weather and see what you get?   

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Michele Benedetti

Will try that in a moment

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Fraser Gale

I am not sure what is going on. 

I have attached the most up to date profile for you to try, these are directly from my PFPX setup and hence created the numbers I have quoted.  Can you check what version of PFPX you are running too? 

In fact, these files have a few added extras that weren't in the original profile, but the planning data is identical. 

Try these and report back.

PFPX Profile Concorde.zip

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Konstantin

May this problem be somehow related to different numbers/time formats/location settings in Windows10?  For example, some countries use comma in numbers as 3-digit separators, some as decimal separators. I had cases where using one program yielded different numbers if the number format was switched from UK to US or vice versa.

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Fraser Gale
11 minutes ago, Konstantin said:

May this problem be somehow related to different numbers/time formats/location settings in Windows10?  For example, some countries use comma in numbers as 3-digit separators, some as decimal separators. I had cases where using one program yielded different numbers if the number format was switched from UK to US or vice versa.

Do you mean within PFPX? 

I am running it on WIN 10 but surely within PFPX a kilogram is a kilogram no matter what Windows it runs on? Or am I missing something?  If I'm getting 91,000kg and someone else is getting 73,696kg for the exact same entries...

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Michele Benedetti

@Fraser Gale I tried the profiles that you uploaded, no changes, however, take a look at these figures in the aircraft list:

 Cattura.PNG.d44ce3af064e8124ca6db9dbbdb503b5.PNG

Are the fuel bias figures correct? 

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Michele Benedetti

As you can see, I created a new airframe using the profile (F-BVFB), using that airframe on the EGLL-TBPB route it gives me a release of something like 91 tons of fuel 

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Fraser Gale
1 hour ago, Michele Benedetti said:

@Fraser Gale I tried the profiles that you uploaded, no changes, however, take a look at these figures in the aircraft list:

 Cattura.PNG.d44ce3af064e8124ca6db9dbbdb503b5.PNG

Are the fuel bias figures correct? 

They are the same as the ones in my profiles so yes.  They simulate the slightly different fuel burn between air frames and I used them to fix the final figures.  You should be getting the same results as I do.

What version number of PFPX are you using? 

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Ray Proudfoot
11 minutes ago, Fraser Gale said:

What version number of PFPX are you using? 

I’m running 2.03 and get very similar results to Michele.

EGLL-TBPB. 83 adult, 5 children, no cargo. Alternate is TFFF. Release 80,893 Kg using PFPX supplied Wx. Same route.

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Michele Benedetti

As Ray does, I'm using PFPX v2.03 

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Fraser Gale
1 minute ago, Michele Benedetti said:

As Ray does, I'm using PFPX v2.03 

Interesting because I am running v1.28 and according to the internal update check I'm on the latest version...

They may have changed some internal settings between my version and yours and I can't do anything about that.  You could try changing the fuel bias to get more accurate results. 

Mental note to myself - DON'T UPDATE PFPX!!!!

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Seth Goodwin
23 minutes ago, Fraser Gale said:

Interesting because I am running v1.28 and according to the internal update check I'm on the latest version...

The internal update check broke at some point, because I recall being very surprised to learn that there was a version 2.03 at one point as well. I had to upgrade as whatever version I had been running began crashing to desktop.

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Fraser Gale
2 minutes ago, Seth Goodwin said:

The internal update check broke at some point, because I recall being very surprised to learn there as a version 2.03 at one point as well. I had to upgrade as whatever version I had been running began crashing to desktop.

As it seems to have made the only profile I use in PFPX inaccurate, I'm glad the update check broke!  I'd be interested to hear if putting the fuel bias to 0% made the profile accurate in v2.03 if anyone can report that back to me. 

@Ray Proudfoot  I remember you asking at the beginning to share the Concorde profile over on another forum somewhere - if that is still accessible, you might want to put a disclaimer saying it is inaccurate after v1.28 for unknown reasons.  

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Ray Proudfoot
2 minutes ago, Fraser Gale said:

 

@Ray Proudfoot  I remember you asking at the beginning to share the Concorde profile over on another forum somewhere - if that is still accessible, you might want to put a disclaimer saying it is inaccurate after v1.28 for unknown reasons.  

I'm pretty sure I didn't do that Frazz. The only place would have been Aerosoft forum that has a subforum for Concorde. And as it's your work it's probably best if you decide where it goes. It's definitely not on AvSim.

At least that solves the mystery. I'm currently flying to Barbados and loaded 95440Kg.

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Ray Proudfoot

Removing the cruise fuel bias for G-BOAC only resulted in release fuel of 88,123Kg. 8000Kg more but still below what is needed.

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Fraser Gale
27 minutes ago, Ray Proudfoot said:

I'm pretty sure I didn't do that Frazz. The only place would have been Aerosoft forum that has a subforum for Concorde. And as it's your work it's probably best if you decide where it goes. It's definitely not on AvSim.

At least that solves the mystery. I'm currently flying to Barbados and loaded 95440Kg.

I've just been through my PM's and you are quite correct, it was one of your competitors :D so apologies for that.

23 minutes ago, Ray Proudfoot said:

Removing the cruise fuel bias for G-BOAC only resulted in release fuel of 88,123Kg. 8000Kg more but still below what is needed.

They must have changed the internal algorithm or format of tables between versions.  The only thing that can be done is fiddle with the fuel bias with no weather until you get sensible numbers. I'm not upgrading to V2 now I know this. 

 

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Ray Proudfoot
11 minutes ago, Fraser Gale said:

I've just been through my PM's and you are quite correct, it was one of your competitors :D so apologies for that.

They must have changed the internal algorithm or format of tables between versions.  The only thing that can be done is fiddle with the fuel bias with no weather until you get sensible numbers. I'm not upgrading to V2 now I know this. 

 

No worries. :) I've tried various values for G-BOAC and +5.8% gives a release load of 95.5T. identical to CPS-X. Agreed they must have changed something fundamental to the calculations.

@Michele Benedetti, try that and see how you get on. As for the other aircraft I see Frazz has slightly different bias values for each but if G-BOAC is okay then he might be able to suggest tweaks to get the others as accurate.

LATER: The bias value above was with the PFPX weather active. Not sure how much that will affect things.

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Michele Benedetti

Will try that immediately Ray!

EDIT:

Ray, I tried the 5.8% with G-BOAC, but it still gives me a release fuel of 92.185 kgs...for sure it's not enough, this was with Active Sky enabled in PFPX and 99 passengers

EDIT n2:

I was using the CONCORDE LR fuel policy, using the normal CONCORDE fuel policy it now gives me a release of 95.349 kgs, with a trip fuel of 78.972 kgs and an ARR FUEL of 14.977 kgs at TBPB

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Fraser Gale
10 minutes ago, Ray Proudfoot said:

No worries. :) I've tried various values for G-BOAC and +5.8% gives a release load of 95.5T. identical to CPS-X. Agreed they must have changed something fundamental to the calculations.

@Michele Benedetti, try that and see how you get on. As for the other aircraft I see Frazz has slightly different bias values for each but if G-BOAC is okay then he might be able to suggest tweaks to get the others as accurate.

LATER: The bias value above was with the PFPX weather active. Not sure how much that will affect things.

I would suggest tweaking with still air ISA conditions otherwise it will have an effect.

As for the different bias figures, I would need to look closely but I would suggest using one aircraft as a reference and taking the difference of the others and using that.

So if 'AC is now 5.8% but had been -14.8% then add 19% to all my original bias figures.  This is assuming that PFPX has had the same effect on all aircraft which I've no way of knowing.  'AC was one of the heavy air frames & had a wing repair so should burn a bit more fuel.

When I get time I'll have a look, problem is there isn't a central place with the files so lots of people might be running out of fuel.....

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Fraser Gale

In addition to above @Ray Proudfoot I'd have said 94,600kg would have been a typical fuel flight plan for Barbados with the captain selecting full tanks, although I don't know what alternate/weather you have in there.

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Ray Proudfoot

@Fraser Gale, I've just run the process again with No Weather and then using the Online PFPX-supplied wx.

For G-BOAC with no wx a value of -1.5% returns 95.7T but when the weather service is activated it drops to 86.4T. Massive difference.

But switching to Active Sky (same wx as I'm using now) it returns 93.9T. Much better and very close to your figure.

I'm not sure how you can feed 'still air conditions' into the calculations. But it looks like if you avoid using the supplied PFPX weather AS will give pretty decent results with -1.5% +/-  a small amount.

I selected TFFF as the alternate as it's the closest.

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Ray Proudfoot
20 minutes ago, Michele Benedetti said:

Will try that immediately Ray!

EDIT:

Ray, I tried the 5.8% with G-BOAC, but it still gives me a release fuel of 92.185 kgs...for sure it's not enough, this was with Active Sky enabled in PFPX and 99 passengers

EDIT n2:

I was using the CONCORDE LR fuel policy, using the normal CONCORDE fuel policy it now gives me a release of 95.349 kgs, with a trip fuel of 78.972 kgs and an ARR FUEL of 14.977 kgs at TBPB

Try -1.4% with Active Sky. That should be very close indeed.

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Fraser Gale
18 minutes ago, Ray Proudfoot said:

@Fraser Gale, I've just run the process again with No Weather and then using the Online PFPX-supplied wx.

For G-BOAC with no wx a value of -1.5% returns 95.7T but when the weather service is activated it drops to 86.4T. Massive difference.

But switching to Active Sky (same wx as I'm using now) it returns 93.9T. Much better and very close to your figure.

I'm not sure how you can feed 'still air conditions' into the calculations. But it looks like if you avoid using the supplied PFPX weather AS will give pretty decent results with -1.5% +/-  a small amount.

I selected TFFF as the alternate as it's the closest.

UVF/TLPL was the normal closest alternate for BGI.

Does this mean if you zeroed the bias and removed the internal weather it would work out like the older version? I suspect the reason all the bias figures were around -15% was because that was how much off v1.28 was.  The actual tables that it reads the data from are as correct as possible and any bias is to simulate difference between air frames or to iron out errors in the program back-end. 

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Ray Proudfoot
15 minutes ago, Fraser Gale said:

UVF/TLPL was the normal closest alternate for BGI.

Does this mean if you zeroed the bias and removed the internal weather it would work out like the older version? I suspect the reason all the bias figures were around -15% was because that was how much off v1.28 was.  The actual tables that it reads the data from are as correct as possible and any bias is to simulate difference between air frames or to iron out errors in the program back-end. 

Alternate noted for next time. :)

With no wx and a bias of 0 it returns 95565Kg. Is that what you're looking for? Looks to me as though bias can be dispensed with generally with just minor values for the different air frames.

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Ray Proudfoot

EGLL-TBPB; G-BOAC; no fuel bias; hold bias remains.

Results...

  1. No Wx. 95565Kg.
  2. PFPX-supplied Wx. 90094Kg
  3. Active Sky Wx. 94422Kg.

Recommendation. Avoid PFPX weather despite having paid for it. Active Sky gives the best results.

@Fraser Gale, updating to 2.03 would solve all your problems.

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Michele Benedetti

Ray, with no bias I get 76 tons of fuel for the KJFK - LFPG route, and with a -1.4 bias I get even less. There must be something that I'm doing wrong otherwise I just can't understand

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Fraser Gale
16 minutes ago, Ray Proudfoot said:

EGLL-TBPB; G-BOAC; no fuel bias; hold bias remains.

Results...

  1. No Wx. 95565Kg.
  2. PFPX-supplied Wx. 90094Kg
  3. Active Sky Wx. 94422Kg.

Recommendation. Avoid PFPX weather despite having paid for it. Active Sky gives the best results.

@Fraser Gale, updating to 2.03 would solve all your problems.

Kinda looks like it...mind you it was an issue I clearly fixed using the bias because I've been using it like that for years!

 

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Fraser Gale
12 minutes ago, Michele Benedetti said:

Ray, with no bias I get 76 tons of fuel for the KJFK - LFPG route, and with a -1.4 bias I get even less. There must be something that I'm doing wrong otherwise I just can't understand

Can you do it for EGLL-TBPB the same as Ray so that we can compare.

Set all bias to 0%

The long range policy allows a little more fuel to be loaded as per real world procedures and the LR fuel policy allows only minimal reserves.

What are you using for your alternate airfield?

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Michele Benedetti

On the EGLL-TBPB route, 98 pax, active sky weather, no long range policy, bias 0%, it gives me 93.724 kgs. Trip fuel 76.706 kgs. With long range policy: 91.202 kgs

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Fraser Gale
8 minutes ago, Michele Benedetti said:

On the EGLL-TBPB route, 98 pax, active sky weather, no long range policy, bias 0%, it gives me 93.724 kgs. Trip fuel 76.706 kgs. With long range policy: 91.202 kgs

I really don't know why you seem to get lower than us.   With 98 PAX I would expect you to be over the maximum fuel possible because the route was "zero fuel weight limited" to around 85 PAX.

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Ray Proudfoot

I used 83 adults and 5 children on G-BOAC. Could 98 be accommodated on that route?

@Michele Benedetti, try my numbers on AC and they should be identical.

Just landed at TBPB with around 10T remaining. Pity I forgot to install the airport scenery so was presented with the default. Yuck!

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Fraser Gale
58 minutes ago, Ray Proudfoot said:

I used 83 adults and 5 children on G-BOAC. Could 98 be accommodated on that route?

@Michele Benedetti, try my numbers on AC and they should be identical.

Just landed at TBPB with around 10T remaining. Pity I forgot to install the airport scenery so was presented with the default. Yuck!

See my post above!  10T was about right and you can see why it was important to get a good weather report before the decel because you could divert to ANU away from storms.  Really once in the descent you are committed to BGI, and weather at UVF would be similar to BGI.  I must admit I've never had bad weather there in the sim...

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Ray Proudfoot
9 minutes ago, Fraser Gale said:

See my post above!  10T was about right and you can see why it was important to get a good weather report before the decel because you could divert to ANU away from storms.  Really once in the descent you are committed to BGI, and weather at UVF would be similar to BGI.  I must admit I've never had bad weather there in the sim...

Really pushed me to the limits though. 1-4 did drop below 1K briefly but I was able to pump fuel from 2 and 3 to assist. Not in the rules I know but better than from 11 as it kept CG rearwards better. But it was only briefly. :D 3h 45m is brilliant when you consider a subsonic 747 takes around 9 hours.

Weather seems to be the same all the time 30C and scattered clouds. I suppose when August arives the chance of hurricanes increases.

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Fraser Gale
31 minutes ago, Ray Proudfoot said:

Really pushed me to the limits though. 1-4 did drop below 1K briefly but I was able to pump fuel from 2 and 3 to assist. Not in the rules I know but better than from 11 as it kept CG rearwards better. But it was only briefly. :D 3h 45m is brilliant when you consider a subsonic 747 takes around 9 hours.

Weather seems to be the same all the time 30C and scattered clouds. I suppose when August arives the chance of hurricanes increases.

You must be leaving it too late to stop aft trim or something.  If you always pump from 11 to 5 & 7 to keep CG at 59% then switch off the pumps to 2 & 3 when fuel is around 2,500kg in 6 & 8 the CG should creep forward slowly so that you have longer in the cruise.  By the decel, make sure aft trim is selected to normal and the fuel in 1,2,3,4 should end up equal by the time you start pumping forward. 

Hurricanes don't worry me in Concorde - autoland and she'll go down to the runway on rails, unlike the subsonics who will toss you all over the place!  Oh, and if you do have to land in high winds, ignore the flying manual wind limits - the excuse was that as you can generally see the runway before normal CAT III limits, any issues could be intercepted unlike in fog.  

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Ray Proudfoot
1 hour ago, Fraser Gale said:

You must be leaving it too late to stop aft trim or something.  If you always pump from 11 to 5 & 7 to keep CG at 59% then switch off the pumps to 2 & 3 when fuel is around 2,500kg in 6 & 8 the CG should creep forward slowly so that you have longer in the cruise.  By the decel, make sure aft trim is selected to normal and the fuel in 1,2,3,4 should end up equal by the time you start pumping forward. 

Hurricanes don't worry me in Concorde - autoland and she'll go down to the runway on rails, unlike the subsonics who will toss you all over the place!  Oh, and if you do have to land in high winds, ignore the flying manual wind limits - the excuse was that as you can generally see the runway before normal CAT III limits, any issues could be intercepted unlike in fog.  

The CG crept forward very close to the forward bug having switched off the pumps to 2 and 3 when there was 2680Kg remaining. Yes, I’m very exact at following your instructions. :)

Two things. CPS-X is under calculating subsonic fuel so that first leg to UPGAS probably needed a little more and tgat could account for needing a little more. I also forgot to switch aft trim forward until the decel had started. Minor things but given I haven’t flown this route in ages overall it went well.

Didn't Concorde have a maximum crosswind for landings?

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Fraser Gale
20 minutes ago, Ray Proudfoot said:

The CG crept forward very close to the forward bug having switched off the pumps to 2 and 3 when there was 2680Kg remaining. Yes, I’m very exact at following your instructions. :)

Two things. CPS-X is under calculating subsonic fuel so that first leg to UPGAS probably needed a little more and tgat could account for needing a little more. I also forgot to switch aft trim forward until the decel had started. Minor things but given I haven’t flown this route in ages overall it went well.

Didn't Concorde have a maximum crosswind for landings?

I wouldn't put money on the subsonic fuel being wrong for a full supersonic flight with CPS.  It is very complicated stuff, and I'm not going to get into it but that isn't really how the Concorde fuel plans work - for real anyway.  Things are calculated in segments: take-off; climb to subsonic cruise; subsonic cruise; climb to FL430/M1.7; supersonic cruise; descent to destination.

On a supersonic flight, the percentage of fuel for subsonic calculation is small compared to climb and cruise hence has less effect on total fuel, whereas pure subsonic operation messes up the segments.  Plus, to do it properly you have to do several iterations of the formula, first with a false fuel figure (to give a total weight to work with) then with the  fuel figure you get from that, then possibly again with the fuel figure you get from the second iteration.   Plus each bit of cruise (sub and super) has to be done in 30 min sections to account for decreasing weight, which on the route out of London would only be one section. 

I don't know whether CPS or PFPX does this.  Doing it manually the crew would use a best guess figure to do the calculations. 

Fascinating stuff, never an exact science and as with everything else for Concorde, EXTREMELY COMPLICATED!!

Was the PFPX figure closer to your actual fuel use?

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Konstantin

I agree that it's hard to come up with a simple equation to calculate fuel for different modes because many variables in Concorde are interdependent. For instance, fuel affects weight, weight affects climb time and altitude profile, and that affects fuel in return, so we are back to the beginning of the variables chain. And then you have to take winds and temperatures into account, which makes it even more complicated.

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Fraser Gale

Definitely no one equation will give fuel required. 

In BA a rather clever flight engineer made his own records of fuel burn on the main routes over several years then wrote a computer program for fuel flight planning that was more accurate than the one provided by the manufacturer.  It ended up being essential to the Barbados route and is the reason they no longer needed a fuel stop in Shannon (most of the time). 

Apparently the figures in the flight planning system had never been altered after the intake modifications which is what prompted him to research his own figures.  What I don't know is whether the figures in the cruise control manual were ever updated from his records, or whether they still have innacuracies in them.  I suspect they were updated. 

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Fraser Gale
10 hours ago, Ray Proudfoot said:

Didn't Concorde have a maximum crosswind for landings?

Forgot to answer this! Yes, the book said maximum head wind 25kt, crosswind 15kt and tailwind 10kt but on at least one occasion that I know of, an Autoland was made at New York with gusts far exceeding this and the autopilot even impressed a CAA test pilot.  The logic was that those limits were for a blind landing where you can't see the runway till 15ft whereas a hurricane landing means rain and strong wind but you can see the runway. 

Concorde was the only aircraft to land within a 4 hour period, all the others had to give up on finals!  The tower asked the crew to phone them from the terminal and said to the SEO that they must have had a very good pilot to get them in with the weather.  When the SEO said they did an Autoland, ATC couldn't believe it - she was the safest aircraft in the sky, even though her statistics were ruined by a certain event. 

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AdrianSmith

My standard Barbados figures are 9 crew 60 pax, ZFW85900, ZFCG52.89, total fuel 95680 which is 100% on the FSL slider.

Always needs a quick pump forwards at the hold to get CG to 54% (54.1 is OK) and even with all that fuel it needs some imagination with the fuel management near ToD to have the CG within limit (right on forward limit) and not have any of tanks 1-4 drop below 1000 Kilos.

Weather rarely makes much difference, above FL400 there is precious little wind anyway; fortunately I have never needed to divert!

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Konstantin
56 minutes ago, AdrianSmith said:

Weather rarely makes much difference, above FL400 there is precious little wind anyway; fortunately I have never needed to divert!

Did you never need to divert in the real life, or in the simulator?  (In other words, did you fly the real Concorde?  I think I have heard of a pilot named Adrian Smith who flew that plane - but I may be wrong). I just wonder if we have real-world Concorde pilots who are using Concorde-X...

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Ray Proudfoot
17 minutes ago, Konstantin said:

Did you never need to divert in the real life, or in the simulator?  (In other words, did you fly the real Concorde?  I think I have heard of a pilot named Adrian Smith who flew that plane - but I may be wrong). I just wonder if we have real-world Concorde pilots who are using Concorde-X...

Adrian works in the aviation industry in Blackpool, England. So no, he's not that Adrian Smith. :) I'll leave him to add anything extra.

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