Absolute minimum temperature?
Thread Starter
Joined: Jan 2007
Posts: 20
Likes: 0
From: Nottingham, UK
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.
Joined: Apr 2010
Posts: 1,320
Likes: 102
From: IRS NAV ONLY
Most aircraft have an environmental envelope published in their AFM, for the B737NG the lower limit is -73.5C from FL360 and above.
Pretty sure somebody else can elaborate on why exactly it is needed.
Pretty sure somebody else can elaborate on why exactly it is needed.
Joined: Jul 2013
Aviation Qualifications: Non-Aircrew
Posts: 5,682
Likes: 3,347
From: Everett, WA
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.
Joined: Apr 2005
Posts: 141
Likes: 15
From: yyz
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 jack@ss makes a skidoo that doesn't run in the winter. Oh right some PQ numb nuts
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
Posts: 7,448
Likes: 310
From: various places .....
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.
Joined: Feb 2001
Posts: 6,729
Likes: 105
From: The Winchester
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
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.
Joined: Apr 2010
Posts: 1,320
Likes: 102
From: IRS NAV ONLY
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
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. :-)
Only half a speed-brake
Joined: Apr 2003
Posts: 4,459
Likes: 136
From: Commuting not home
For the 737 I could not find the environmental envelope chart in any of the FCOMs I caught online. Somebody above said it's inside the AFM.
The graph I posted is from Continental Airlines 772 FCOM, 2002 edition. Probably heavily tailored. https://curiozitydotnet.files.wordpr...ght-manual.pdf
The 747 FCOM found is ZK-SUI from ILFC and content-wise looks identical with the 737 in the Limitations Chapter. No Environmental Envelope Graph.
The graph I posted is from Continental Airlines 772 FCOM, 2002 edition. Probably heavily tailored. https://curiozitydotnet.files.wordpr...ght-manual.pdf
The 747 FCOM found is ZK-SUI from ILFC and content-wise looks identical with the 737 in the Limitations Chapter. No Environmental Envelope Graph.
