Page 173 - Aeronautical Engineer Data Book

144 Aeronautical Engineer’s Data Book
9.5 Aircraft emissions
Aircraft engine emissions vary with the type of
engine, the fuel source used, and the opera­
tional profile. Emission levels are governed by
ICAO recommendations. For comparison
purposes the flight profile is divided into the
take-off/landing segment and the cruise
segment (designated for these purposes as part
of the flight profile above 3000 ft). Table 9.4
shows an indicative ‘emission profile’ for a
large four-engined civil aircraft.

Table 9.4 An indicative ‘emission profile’
Emissions in g/kg fuel

CO NO x * SO 2 HC (unburnt)
Take-off 0.4 27 0.5 0.06
Cruise >3000 ft* No agreed measurement method.
Varies with aircraft and flight profile
Approach/landing 2.0 11 0.5 0.12

*Some authorities use a NO x emission index as a general measure
of the level of ‘amount of pollution’ caused per unit of fuel burnt.