Aircraft Emissions

Date:         21 Nov 96 03:02:19 
From:         Judith Patterson <>
Organization: Concordia University, Montreal, Canada
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I am a researcher in the field of aircraft emission inventories at
Concordia university.  Right now, I am looking at the variability that
can occur in the emissions produced during takeoff and landing operations
at airports.  I am hoping to hear from those who actually do the flying -

According to the EPA and ICAO standards, the portions of the LTO cycle
are divided as follows with power rating and time in mode:
takeoff 100%    0.7 minutes
climbout 85%    2.2 minutes
approach 30%    4.0 minutes
taxi/idle/queue         highly variable, depends on airports, standard
    assumed to be 26 minutes

These estimates for time in mode were derived from industry averages, and
are for large, turbojet or turbofan aircraft, not turboprop or piston.
They have their own times in mode estimates.

What I am curious to know is how much variability there can be in the
amount of time in takeoff and climbout, and to a lesser degree, the
approach phases.  For example - what is the difference in the amount of
time at 100% power for a fully loaded 747-400, lumbering down the runway,
and a 747 only 40% full with passengers?  How much variability can there
be?  I have conducted my own unofficial survey - all 747-400's need to be
at 165 mph to lift up the front wheel (they now show ground speed on the
monitors on the trans-Atlantic flights) but it seemed that when I was on
a flight only about 35% loaded that we lifted off about half way down the

How great a range can there be in the amount of time in mode?

Do airlines make changes in the amount of fuel that they put on knowing
the approximate passenger consist?  How great a difference does this make
in takeoff weight?

I would greatly appreciate any and all information.

Please cc all replies to my e-mail:

Thanks, Judith