Jet Departures from Livermore Airport:  Part 2.  Six Weeks of Recorded Departures

Introduction

This post is a continuation of the issue of jet noise at Livermore Airport that has been described elsewhere in this Blog. While the airport experiences noise complaints for both jet and non-jet operations, the noise complaint statistics reported through the end of April of this year reveal a majority of complaints are due to jet operations, 882 out of 1453 complaints. A little more than half of the complaints originate in Pleasanton and the remainder in Livermore. Since prevailing winds throughout the year are generally from the west, most jet departures are toward the west and impact the residential neighborhood that begins 1.4 statue miles directly west of the departure end of Runway 25R. For the reporting period a total of 322 Pleasanton noise complaints originated due to these departures.

A substantial number of jet operations were recorded during the period May 1 ending June 11. Some of this data is presented below as well as some take aways that result. The data demonstrates that how the pilot flies the departure is a determining factor that generates noise complaints.

Map View

The following map locates the Pleasanton areas most sensitve to jets departing to the west.

Two points of reference are where the residential begins after a jet departs toward the west and where the extended centerline of the runway intersects Santa Rita Road near Valley hospital.

Example of Noisy Operation Versus Noise Abated Operation

The data set produced two examples that stand out. The map view of what is considered noisy operation is N819AP, a jet hangared at Five Rivers Aviation at the airport.

The items to note are:

• Climb gradient is particularly low.
• Pilot appears to stay low in order to accelerate the aircraft to 198 KTS rather than climb more steeply at a lower airspeed.
• Pilot flies over the entire residential area including the hospital before slowly turning northbound per the LVK Three Standard Instrument Departure.

An example for which noise experienced by residents is much reduced is seen in the next map view.

Items to note are:

• Climb gradient is substantially high. Angle of climb of 15.2 degrees is substantial.
• Pilot maintains an airspeed of 146 KTS, consistent with the steep climb.
• Pilot turns northbound and crosses I-580 approximately at the location of Carmax and therefore avoids direct overflight of houses.

While the map view of jet departures is informative, a profile view of departures provides a good view of altitudes.  Profile views presented here are those of an observer looking north as aircraft depart the runway on the right and climb westward toward the houses on the left. The following profile view shows how dramatically different the two departures are. Note that the altitude in the view is feet above ground level.

The items to note are:

• N819AP is quite low as it flies over the entire residential area.  It is barely at 800 feet above the houses as it crosses the boundary where houses begin.
• LXJ348 never overflies any houses and when it is close to this boundary it is already 3 times higher than N819AP!  (Also note that the point at which the plotted track terminates indicates the aircraft has crossed I-580.)

Netjet Operations

A clear takeaway that the data demonstrates is that Netjet pilots appear to systematically follow noise abatement procedures.  Departures recorded during the month of May demonstrate this.

Items to note are:

• Except for two departures, all are at least at 1500 feet above ground as they overfly the boundary where houses begin. The other two are a bit lower, at 1300 feet above ground.
• All departures turn north early enough so that only a portion of the residential neighborhood is overflown.

Departures during early June show the same.  All are at least 1500 feet above ground before overflying any houses.  It seems that Netjet pilots receive the same training.  Since Netjets operates nationwide it would make sense that its pilots encounter many airports with noise sensitive areas and therefore trains its pilots to get high quickly and follow closely any applicable SID.

Some N819AP Departure History

Not all departures by this aircraft are so noisy as the example above.  All of these jet operations involve two pilots.  N819AP history seems to demonstrate that one pilot operates the aircraft in a more noise abated procedure than the other.

One can see in the profile the offensive example but the others cross the boundary where houses begin at altitudes above 1000 feet above the ground.  Only a few are near 1500 feet which the Netjet pilots do and where residential overflight is partial.  Many departures overfly the majority of the houses.  Which pilot is operating the aircraft appears to be distinguishable.

All Jet Operations

Jet operations at Livermore Airport are conducted by a great variety of operators. So the question arises naturally what are the departure profiles overall. Two views provide an answer. The first is for the month of May where most of the jet departure operations were recorded.

The results in the profile view look daunting, but a simple interpretation can be made.  The lower altitude tracks are seen to mostly pass over all of the houses while the upper altitude tracks do not.  If one splits these tracks into two populations, lower altitudes and higher altitudes, a substantial improvement in noise abatement would result if the pilots of the “lower” population were to operate their aircraft like those pilots in the “higher” population.

A similar interpretation applies to operations recorded through June 11. 

In this profile view one jet departed VFR and turned south, which explains the track that appears unlike the others.  The aircraft never crossed I-580 and therefore the track continued to be plotted to 4000 feet above the ground.

Conclusions

Whether a jet departure is “noisy” versus “noise abated” is dependent upon how the pilot operates the aircraft upon departure.  Since nearly all of these aircraft are operated by two pilots (captain and co-pilot) sometimes the same aircraft will be observed in both categories, indicating which pilot is piloting during departure.  Netjet pilots as a group appear to be trained to consistently depart with noise-friendly steep climb gradients.

The recorded data evidences that increased pilot awareness and willingness to conduct noise abatement departures is needed.