Absolute minimum temperature?
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Join Date: Jan 2007
Location: Nottingham, UK
Age: 74
Posts: 18
Absolute minimum temperature?
Is there a Boeing limit of absolute minimum OAT? (Not minimum fuel temp)
The lowest I personally observed was -74*C at FL450 over the Baltic, but was told by a BA F/E that he had seen -85*C over Siberia.
Is there a limit and why? Thanks.
The lowest I personally observed was -74*C at FL450 over the Baltic, but was told by a BA F/E that he had seen -85*C over Siberia.
Is there a limit and why? Thanks.
Join Date: Jul 2013
Location: Everett, WA
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Not quite - you're allowed to extrapolate to some extent, but generally allowed when there is some previous data that validates the extrapolation methodology.
Another issue is many of the data tables only extend over a specific temperature and altitude range - e.g. engine ratings. I recall an issue perhaps six or seven winters ago when a big cold front hit part of Europe - it was bitter cold, but more importantly the pressure altitude dropped well below -1000 ft. The takeoff performance data for some types didn't go below -1,000 ft., resulting in several aircraft being grounded for several days.
Another issue is many of the data tables only extend over a specific temperature and altitude range - e.g. engine ratings. I recall an issue perhaps six or seven winters ago when a big cold front hit part of Europe - it was bitter cold, but more importantly the pressure altitude dropped well below -1000 ft. The takeoff performance data for some types didn't go below -1,000 ft., resulting in several aircraft being grounded for several days.
Join Date: Apr 2005
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Most tends to be a fuel gel point, read about a DC10 over Russia years back that was reaching min tank temp. ATC wouldn't allow any deviation lower/faster etc....... the F/O suggested wing deice, the temp slowly rose due to hot bleed air in the leding edge. Several years back air canada was stuck in yzf for 2 weeks because the temps didn't rise above -48 during that time, what [email protected] makes a skidoo that doesn't run in the winter. Oh right some PQ numb nuts
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Been plenty of incidents over the years with fuel gelling. BA38 comes to mind. An aircraft which I was looking after, some years ago, nearly came to grief on the way to NZ - fortunately the PIC recognised the symptoms from a conference paper several years prior, descended, and the problem resolved.
Join Date: Oct 2019
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738-800 fuel filter bypass
Back around 2008, when flying in -64°C +/- temps for any length of time, for example, from STN to Tampere, about the time of TOD, we could expect to get a master caution and fuel filter bypass which would clear by the time we had parked on the ramp. I think there used to be a bulletin but it was removed some time ago, due to some tech mods perhaps.
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Only half a speed-brake
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Stolen shamelessly from the inter-web. Continental's 777-224, dated 08/09/02 (for whatever Christmas sake that means?).

The left edge-line is relevant, showing a binding limit at -75° C when above FL315.
On Airbuses the FCOM chart is pretty much the same.

The left edge-line is relevant, showing a binding limit at -75° C when above FL315.
On Airbuses the FCOM chart is pretty much the same.
Join Date: Oct 2019
Location: north pole
Posts: 53
no joy....yet
after looking until eyes glazed over, using 50/50, ask the audience and phone a friend, I will stick with my memory of -65C. I am sure of winter before last, several other colleagues, in same airline and same a/c requesting descent due to low temperature enroute. i think I remember our ops manual or performance manual having a chart like the above 777 environmental envelope, but I cannot find it. Yet.
I did see, the lowest temperature on the TO performance charts as -40C for -800 and -60C for -700. And oddly, the quick turnaround brake charts show -54C.
the emergency O2 chart for flight deck shows a low of -10.
I did see, the lowest temperature on the TO performance charts as -40C for -800 and -60C for -700. And oddly, the quick turnaround brake charts show -54C.
the emergency O2 chart for flight deck shows a low of -10.
Last edited by 70 Mustang; 10th Jan 2021 at 15:02.
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Only half a speed-brake
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70 Mustang Your charts say TAT, mine OAT. Reader beware.
Check Airman It's the spirit of the date, not the format that matters. :-)
Check Airman It's the spirit of the date, not the format that matters. :-)
Join Date: Oct 2019
Location: north pole
Posts: 53
Max min i could find...
TAT -65C is the coldest i could find in any chart.
Do you have a page number or a screenshot of your chart? I cannot find it.
I only have FCOM, FCTM and the above Flight Planning and Performance Manual.
I haven’t seen an AFM for the 737-800 since 2003 at Excell Air at LGW.
Do you have a page number or a screenshot of your chart? I cannot find it.
I only have FCOM, FCTM and the above Flight Planning and Performance Manual.
I haven’t seen an AFM for the 737-800 since 2003 at Excell Air at LGW.
Last edited by 70 Mustang; 30th Dec 2020 at 19:42.