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17 cartridges, and thermal desorption tubes--were used. After Turboprop, 1 Learjet, 10 the field campaign was completed, analysis of the DNPH B727, 8 MD-80, 9 cartridges and SUMMA canisters revealed anomalous CO2 MD-11, 2 concentrations, which were attributed to a leak in a subsystem DC-10, 13 of the sampler. Also, C4-C12 HC values based on the concen- trations measured from the thermal desorption tubes (TDS) CRJ, 13 were much lower than expected from APEX1 and other re- search. Since this leak introduced an unquantifiable dilution A320, 16 in these subsystems, the emission factors for the light HC and A310, 1 carbonyls could not be calculated. A300, 5 The second set of measurements sampled jet engine ex- B757, 7 haust downwind of an active taxiway and runway at OAK while the aircraft performed standard LTO. The runway tests demonstrated the potential of downwind emissions B737, 177 monitoring adjacent to active taxiways and runways as a means to rapidly acquire evolving aircraft PM characteris- tics from in-service commercial aircraft. Emissions were monitored during a 12-hr period of daylight aircraft opera- Figure 9. Distribution of aircraft activity as a function of airframe. tions along a single runway where the downwind exhaust plumes for over 300 aircraft were sampled. An aerial view of the test venue is shown in Figure 8. Mobile laboratories August 26, 2005. Aircraft tail numbers and operational status from Missouri S&T and ARI were collocated downwind on (i.e. taxi, takeoff, and landing) were acquired through visual the eastern end of the runway with the prevailing wind direc- observation, including video recordings. Aircraft-specific tion coming from the W/NW. The Missouri S&T laboratory airframe and engine data were obtained by correlating these focused on the physical characterization of the downwind tail numbers with an FAA database. Figure 9 illustrates the PM and measurement of CO2 (Whitefield et al. 2007). The distribution of aircraft types operating at OAK during the day ARI laboratory focused on characterization of PM compo- of the tests. In all, exhaust from 15 different airframe types sition and measurement of CO2, and trace combustion gases was captured, and approximately 63% of the aircraft were (Herndon et al. 2007). B737s. Over 300 aircraft landings and departures were detected and monitored during the period from 7 A.M. to 7 P.M. on 3.4 APEX3 APEX3 was the fourth campaign in the APEX series. The main objective of APEX3 was to advance the knowl- edge of aircraft engine particle emissions. APEX3 was con- ducted at Cleveland Hopkins International Airport (CLE) from October 26 to November 8, 2005. In APEX3, as in the three previous studies, engine exhaust emissions and plume devel- opment were examined by acquiring data from the exhaust nozzle and in the near-field plume from a range of stationary Preva commercial aircraft. A complementary study of downwind iling w ind plumes during normal operations was abandoned because the prevailing winds during the scheduled sampling times did not transport the plumes to the available sampling locations. As with previous studies, APEX3 was a collaborative re- search effort and was supported by the following organizations: (1) Researchers from NASA, EPA, U.S.DOT Volpe Center, the Air Force Arnold Engineering Development Center (AEDC), Missouri University of Science and Technology Figure 8. Aerial view of the OAK test venue (Missouri S&T), Montana State University (MSU), and for downwind plume monitoring. Aerodyne Research, Inc. (ARI);

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18 (2) Engineers from the aviation industry including Conti- engines) provided by Express Jet, passenger aircraft (B737- nental, Express Jet, FedEx Express, General Electric, 300 with CFM56-3B1 engines, B757 with RB211-535E-4B Pratt and Whitney, Rolls-Royce, and Rolls-Royce North engines) provided by Continental Airlines, a freight aircraft America; and (A300-600 with PW4158 engine) provided by FedEx, and the (3) Sponsors from FAA, EPA, NASA, and Cleveland Hopkins NASA general aviation aircraft (Learjet 25 with CJ610 turbo- International Airport. jet engines). Engine exhaust was sampled at three different locations in the plume, nominally 1 m (3 ft) (i.e., exhaust Particulate matter and gas-phase emissions were acquired nozzle), 15 m (49 ft), and 30 m (98 ft) for the small aircraft from a range of current in-service commercial aircraft engines (regional jet and general aviation jet), and 1 m, 30 m, and 45 m including regional aircraft (ERJ 135/145 equipped with AE3007 (3 ft, 98 ft, and 148 ft) for the large aircraft.