Flat Rated Temperature ISA + 15 - E-Jets

P-air · 08-03-2009, 05:48 AM

Wow, have been flying the E-jet for nearly 5 years now, and never even realised the engines were temperature limited at ISA + 15

Flying in India has seen the Flight Levels a lot warmer than in other parts of the world, and have been very curious why the aircraft here have been very slow to climb. And soon discovered the ISA+15 Flat Rate limit after looking a little closer.

I wonder why this small detail never made it into the AOMs or AFM, or general information to crews. It sure is an important detail that significantly impacts performance.

Anyone have any idea on just how much a reduction on the Thrust modes, each degree above Isa +15 has? Or anyone have a chart plotting expected thrust available for each mode at temps above Isa + 15?

yoda · 10-03-2009, 12:46 AM

It's in the AOM under the table that shows thrust ratings.

It's also discussed at length during the type rating course we offer.

Many of the tables in vol 1 chapter 5 have isa deviation and in particular if you look at the climb gradient tables you can see clearly the drop off above isa + 15.

Some engines are flat rated to isa + 20 but not yours!! p.s have you paid the rent yet?

08-03-2009, 05:48 AM	#1
P-air Senior Member Join Date: Mar 2007 Posts: 346	Flat Rated Temperature ISA + 15 Wow, have been flying the E-jet for nearly 5 years now, and never even realised the engines were temperature limited at ISA + 15 Flying in India has seen the Flight Levels a lot warmer than in other parts of the world, and have been very curious why the aircraft here have been very slow to climb. And soon discovered the ISA+15 Flat Rate limit after looking a little closer. I wonder why this small detail never made it into the AOMs or AFM, or general information to crews. It sure is an important detail that significantly impacts performance. Anyone have any idea on just how much a reduction on the Thrust modes, each degree above Isa +15 has? Or anyone have a chart plotting expected thrust available for each mode at temps above Isa + 15?

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10-03-2009, 12:46 AM	#2
yoda Junior Member Join Date: Apr 2007 Posts: 25	It's in the AOM under the table that shows thrust ratings. It's also discussed at length during the type rating course we offer. Many of the tables in vol 1 chapter 5 have isa deviation and in particular if you look at the climb gradient tables you can see clearly the drop off above isa + 15. Some engines are flat rated to isa + 20 but not yours!! p.s have you paid the rent yet?