El Toro Flight Tests Wouldn’t Work

Much has been said about conducting flight tests to allow county residents to assess the noise impact of converting El Toro Marine Corps Air Station to a commercial airport. While the reuse plan and draft environmental impact report (EIR) have been deficient in describing the noise an airport would generate, flight tests would also fall short.

Flight tests that would indicate the noise impact of a commercial airport with any sort of accuracy are not possible for the following four reasons:

The airport infrastructure will change significantly from what currently exists. While the community reuse plan prescribes retaining the present inefficient and unwieldy general airfield layout, FAA regulations regarding runway slope and separation mandate reconstruction of 2 1/2 of the four runways. Neither of the two departure runways is presently able to handle commercial aircraft, and thus no meaningful flight test of departure aircraft noise can be accomplished.

The noise characteristics of aircraft are highly dependent on how the aircraft is operated. True assessment of aircraft noise is possible only if a realistically loaded aircraft is flown at the proper speed on the proper flight path. Unless the test planes are flown as such, people will be misled about the noise they can expect. The misleading demonstration, actually conducted at the El Toro Air Show by a commercial cargo carrier, of flying an overpowered aircraft (Boeing 757) empty and using energy management techniques to keep the engines at idle at selected times tells us nothing. An accurate depiction of 757 approach noise is buried in the Draft EIR Technical Report H, Noise Analysis. Exhibit 28 indicates that a new 757 will generate the same noise on approach as a 30-year-old 727.

The draft EIR has not honestly indicated how aircraft will operate into and out of El Toro. While the EIR noise model assumed aircraft flying “straight-ins” to runways 34L & R, FAA wake turbulence separation requirements would not permit this given the runway separation that is planned. At San Francisco International Airport, where the runway separations are similar to the El Toro proposal, the angles aircraft approach at are changed to deal with wake turbulence.

The effects of frequency and times of noise events cannot be accurately simulated by flight tests. The EIR Noise Analysis mentions in general terms the relationship between annoyance and noise loudness, frequency and time of day. Even though the noise model used considers such factors, the “average” noise contours it generates do not begin to describe the impact of constant day and night noise, and neither will isolated flight test noise events.

If decision makers are serious about listening to those who will be affected, providing accurate and honest information on which residents can base a decision is essential. Flight tests do not meet this criteria. They would be unrealistic and an invitation for manipulation by airport promoters.