Chapter 6 – Helicopter Landing Area Siting Analysis

BEND MUNICIPAL AIRPORTAirport Master Plan Update

Chapter 6 – Helicopter Landing Area Siting Analysis

City of Bend Oregon – Bend Municipal Airport Master Plan Update

Chapter 6 – Helicopter Landing Area Siting Evaluation The purpose of this chapter is to identify and evaluate potential sites on Bend Municipal Airport for the

development of helicopter facilities (heliport) that can be established as an independent landing area with

protected airspace surfaces, similar to a runway.

Purpose and Need

Currently, all helicopter operations at the Airport are accommodated within the runway-parallel taxiway system. The existing helicopter and fixed-wing traffic patterns are designed to separate these aircraft within the same operating area, although all of the aircraft approach and departure paths are aligned near the runway ends. While fixed-wing aircraft takeoff and land on the runway, most helicopters use the parallel taxiways on either side of the runway for their operations. This practice is common at airports without designated helicopter landing areas. From an airfield capacity perspective, all air traffic at Bend Municipal Airport is currently attributed to the runway.

The development of independent helicopter landing area on the Airport will provide several benefits:

1. Improved air traffic distribution for helicopters and fixed wing aircraft.

Chapter 6 – Helicopter Landing Siting Evaluation November 2012- 1


2. Reduced helicopter activity on parallel taxiways will improve operational flow for taxiing fixed wing aircraft.

3. Increased airfield capacity (with adequate separation from the runway). 4. Reduces the need to enhance capacity (high speed exit taxiways, etc.) for the existing runway-

taxiway system to accommodate forecast demand in the current 20-year planning period.

5. Ability to provide additional landside development capacity (aircraft parking, hangars, etc.) designed for helicopters.

6. Provides efficient facility configuration for future air traffic control tower operation.

Based on the preliminary evaluation of proposed helicopter landing area sites on the Airport, additional refinement of facility configurations (parking layouts, hangar development areas, etc.) will be incorporated into the airport alternatives evaluation. In general, the three landing area sites identified in this chapter have relatively similar development potential and are considered feasible from an operational standpoint. A primary difference between the sites is related to the location of the helicopter traffic pattern and the typical arrival and departure routes for the aircraft.

Existing and Forecast Helicopter Activity

As noted in the updated aviation activity forecasts (see Chapter Four, Table 4-15), helicopter operations currently account for about 40 percent of overall airport air traffic at Bend Municipal Airport. Based on operator-recorded flight hours, helicopter activity in 2010 was estimated at 39,840 annual operations. The majority of these operations were accommodated on the west parallel taxiway, which is adjacent to west side helicopter parking areas and training facilities. The new east parallel taxiway was opened for use in late 2010. The master plan forecast projects helicopter operations to increase to 63,070 by 2030. The majority of the helicopter activity is associated with flight training.

The FAA recommends that airports begin planning for additional airfield capacity when annual demand reaches approximately 60 percent of annual capacity. As indicated in the facility requirements analysis (see Chapter 5, page 58), it is estimated that Bend Municipal Airport is currently operating at approximately 43 percent of annual capacity. By 2030, the Airport is projected to be operating at 69 percent of annual capacity, based on the existing airfield configuration.

Since helicopter operations account for a significant portion of total airport operations, the most cost-effective way to maintain adequate runway capacity is to shift a large portion of helicopter traffic to a dedicated helicopter landing area. Hillsboro Airport, which also accommodates significant helicopter flight training activity, divides helicopter activity between two parallel taxiways and one helicopter landing area (3 landing pads) with three separate helicopter traffic patterns.



Existing Helicopter and Fixed-Wing Traffic Patterns

The airport traffic patterns at Bend Municipal Airport have been configured to accommodate helicopters and fixed wing aircraft operating in the runway-parallel taxiway environment. Figure 6-1 illustrates the existing airport traffic patterns, as created by the Airport’s “Fly Friendly Program” that helps pilots to avoid unnecessary flight over nearby noise sensitive areas east of the Airport.

The traffic patterns for fixed-wing aircraft are standard “left traffic” configurations, which require aircraft to make a series of left turns within the pattern. When Runway 16 is in use, the fixed wing traffic pattern is on the west side of the runway; when Runway 34 is in use, the traffic pattern shifts to the east side of the runway to maintain standard “left traffic.” The fixed-wing traffic pattern altitude is 1,000 feet above ground level (AGL). The fixed-wing traffic pattern length and width reflects the typical maneuvering requirements of general aviation aircraft. At uncontrolled airports, the standard procedure for entering an airport traffic pattern is to enter at a 45-degree angle near the midpoint on the downwind leg that is parallel to the runway and maintain adequate spacing from other aircraft in the pattern.

The traffic patterns for helicopters at Bend Municipal Airport are “right traffic” configurations, which require aircraft to make a series of right turns within the pattern. This allows the helicopter and fixed-wing traffic patterns to be physically separated on opposite sides of the runway, except when their paths merge during takeoff and landing modes. When Runway 16 is in use, the helicopter traffic pattern is on the west side of the runway; when Runway 34 is in use, the traffic pattern shifts to the east side of the runway to maintain “right traffic.” During final approach for landing, the helicopters adjust course slightly to align with the parallel taxiways. The helicopter traffic pattern altitude is 500 feet above ground level (AGL) and the pattern length and width is smaller than the fixed wing pattern based on the typical maneuvering requirements of helicopters.

The current operational procedure for on-airport helicopter flight training is to use the parallel taxiways to accommodate a series of landings and low-altitude hover taxiing. The helicopters move to the side of the taxiway (hover or landing) to accommodate fixed wing aircraft taxiing. The area between the runway and west parallel taxiway is also used for normal takeoffs and landings with aircraft hover-taxiing to adjacent hangar or parking positions.



Proposed Helicopter Landing Area Sites

Based on an evaluation of developable lands within airport property, it was determined that east side of Bend Municipal Airport has adequate space to accommodate proposed helicopter landing areas in several (undeveloped) locations. The west side of the Airport does not have the ability to accommodate a helicopter landing area without displacing existing aircraft parking apron or hangar development. For this reason, the evaluation of proposed helicopter landing area sites will focus on the east side of the airport.

FAA Advisory Circular (AC) 150/5390-2C Heliport Design, and FAR Part 77, Objects Affecting Navigable Airspace are the primary technical guides for planning of helicopter landing facilities. Per FAA guidelines, the proposed helicopter landing area sites must be capable of accommodating several defined areas including the Final Approach and Takeoff Area (FATO), the Touchdown and Liftoff Area (TLOF), the Safety Area and Protection Zone, and the Approach and Departure Surface. The dimensions of these areas are defined by the size of helicopter planned that would be expected to operate on the landing pad.

FAR Part 77 airspace (approach, primary, and transitional surfaces) also extend from the helicopter landing area. For planning purposes, the areas defined for the helicopter landing area at Bend Municipal Airport are based on use by large helicopters, which will enable the Airport to accommodate both small flight training aircraft and larger military or fire related aircraft. The approach and departure surfaces for helicopter landing areas rise at a slope of 8 to 1 and extend 4,000 feet. At a slope of 8:1, the distance to clear a 35-foot tall structure (typical large commercial hangar) is 280 feet. The potential effect of turbulence created by air flowing over nearby buildings is also considered when siting roof-top and ground-level helicopter landing areas.

The ability to provide an unobstructed approach and departure paths was a primary consideration in identifying potential sites. Based on existing airport traffic patterns, it is assumed that the helipads will have north and south approaches that parallel the approaches for Runway 16/34. The helicopter landing pads are surrounded by a primary surface and a 2:1 transitional surface extending from the sides of the pads that must be free of structures, parked aircraft, and other obstructions.

The helicopter landing pad, also known as the Touchdown and Lift Off Area (TLOF) would be 100 feet by 100 feet and constructed of Portland Cement Concrete (PCC) to accommodate large helicopters. With the proposed multiple pad configuration, the second TLOF could be smaller (typically 50 feet by 50 feet) based on the needs of small training helicopters. The helicopter landing areas would be connected by paved taxiways (25 feet wide) to accommodate ground taxiing of wheel-equipped helicopters. The taxi routes for helicopters require an obstruction free path approximately 100 feet wide to accommodate large helicopters. Heliport lighting is recommended to provide improved operational visibility at night



and during poor weather conditions. Perimeter lighting (yellow) is used to define the limits of the operational surface area associated with the helipad and taxiway lights or reflectors (blue) are used to define the edges of taxiways. Since the helicopter landing area will be located on an existing airport, a separate rotating beacon is not required. The development of a helicopter (copter) instrument approach to the landing area may also be considered, although based on the proposed separation distances with the runway, simultaneous instrument approaches are not anticipated.

Based on the large volume of helicopter flight training activity at the Airport, the proposed sites are configured with two landing pads separated 600 feet apart, aligned to be parallel to the runway. This configuration is similar to the helicopter landing pads at Hillsboro Airport, which has three pads in line over a distance of 1,200 feet. The pads are aligned parallel the airport’s main runway. At Hillsboro Airport, the control tower is able to clear several aircraft into the designated helicopter area at one time. This allows extended time for various training activities and increases the capacity of the landing area.

Another consideration in siting a helicopter landing area on the Airport is the ability to operate simultaneously with Runway 16/34. The FAA standard for simultaneous operations between parallel runways in visual flight rules (VFR) conditions is 700 feet (centerline-to-centerline). Although the FAA allows a separation 500 feet for runways and helicopter landing areas used by small or medium helicopters, 700 feet is required for helicopter pads used by large helicopters. For planning purposes a minimum runway separation of 700 feet is used for all proposed helicopter landing area sites.

East Side Landing Pad Siting Options

Figure 6-2 depicts three proposed helicopter landing area sites on the east side of Bend Municipal Airport. The landing area defined for each site has two landing pads that are aligned parallel to Runway 16/34, with approach/departure surfaces extending north and south. The approach surfaces for the landing areas have adequate clearance over adjacent buildings and reference points are added to identify the distance required to clear a 35-foot tall structure, which represents a typical large commercial hangar. A rectangular protected area is depicted surrounding the helicopter landing areas to represent the protected surfaces on the ground and the FAR Part 77 primary and transitional surfaces.

Site A is located 700 feet east of the Runway 16/34 centerline near the threshold of Runway 16. The site provides clear approaches to the north and south. The site is located within the 500-foot radius clear area for the Airport’s Automated Weather Observation System (AWOS). This is consistent with FAA criteria and existing development on the Airport (the AWOS clear area currently extends over the north end of the runway and east parallel taxiway). All landside development (aircraft parking, hangars,



etc.) associated with this site would be located outside the AWOS clear area, east of the landing pads to meet FAA requirements.

Site B is located approximately 1,658 feet east of the Runway 16/34 centerline near the northeast corner of the airport. The site provides clear approaches to the north and south. The helicopter landing pads and landside development (aircraft parking, hangars, etc.) associated with this site would be located outside the AWOS clear area. Landside facilities associated with this site would be located west or south of the landing pads.

Site C is located approximately 1,108 feet east of the Runway 16/34 centerline in the vicinity of the old pond, north of the Cessna facilities. This area was the site proposed to develop a helicopter landing area in a recent Connect Oregon grant application. The site provides clear approaches to the north and south over nearby buildings, although it is significant more constrained than Site A or B. Landside facilities associated with this site would be located west or south of the landing pads. It is noted that a portion of this site is currently leased which may affect its development potential as a public use helicopter facility.



Proposed Changes in Airport Traffic Patterns

The development of a helicopter landing area on the east side of Runway 16/34 creates the need to modify the existing airport traffic patterns to accommodate independent traffic patterns for the two landing areas. The separation proposed between the runway and helicopter landing area locations would create significant overlaps between fixed wing aircraft and helicopter traffic when Runway 16 is in use. The current right traffic helicopter pattern for north landings would require helicopters to cross the final approach for fixed wing aircraft landing on Runway 16 to reach a landing area on the east side of the runway. Segregating the traffic on the east and west sides of the runway appears to be the most practical solution available to address the change in airfield configuration.

Figure 6-3 depicts a west-side pattern for the runway-taxiway system and an east-side pattern for helicopters. This configuration would allow aircraft to travel within the fixed wing and helicopter patterns without overlapping. The fixed wing pattern would be left traffic for Runway 34 and right traffic for Runway 16. The helicopter pattern would be left traffic for north landings (parallel to Runway 16) and right traffic for south landings (parallel to Runway 34).

The precise location of the east side traffic pattern would be determined by the selected helicopter landing pad location. Based on current flight procedures, it appears that the traffic patterns for Sites A and C can remain clear of the noise sensitive area identified east of the airport and would be most similar to the existing eastside helicopter traffic pattern. The traffic pattern for Site B extends further east due to its location near the northeast corner of the airport. It appears that the location of Site B could be shifted further west to mitigate the traffic pattern over flight, although the development of helicopter landside facilities (aircraft parking, hangars, etc.) would need to be modified to avoid the airport’s automated weather observation system (AWOS) clear area.

It appears that each of the three proposed helicopter landing area sites can accommodate east traffic patterns that would be compatible with a west traffic pattern for Runway 16/34. The primary difference among the three proposed locations is the easterly shift of aircraft traffic pattern required for Site B over the western edge of the adjacent noise sensitive area.



Helicopter Noise Evaluation

An evaluation of helicopter noise exposure was conducted for the proposed helicopter landing areas east of Runway 16/34 using the FAA Integrated Noise Model (INM). For the purposes of comparing the proposed sites, the noise evaluation used common operations data and flight track configurations consistent the with the proposed helicopter traffic patterns depicted in Figure 6-3.

The aircraft operations data is based on the 2030 forecast of helicopter operations (63,070). The evaluation assumes that 80 percent of the helicopter operations will utilize the east helicopter landing area and 20 percent will use the west parallel taxiway. The aircraft mix reflects a heavy concentration (80 percent) of piston engine small helicopters (Robinson) commonly used for flight training with the remaining 20 percent medium and large turbine helicopters (Bell 206, Bell 212).

Figure 6-4 depicts the noise exposure associated with the forecast 2030 helicopter operations for the proposed landing areas on the east side of airport. It is noted that the 2030 forecast helicopter operations level is 58 percent higher than 2010 activity; as a result the noise contours depict future noise exposure based on projected activity that is significantly greater than current exposure levels.

The proposed sites for the helicopter landing area vary in the separation distances east of the runway. This results in the eastern edges of the noise contours shifting further east for Sites B and C, compared to Site A, which is located 700 feet from runway centerline. The areas of moderate or higher noise exposure (65 DNL and above) associated with the forecast 2030 helicopter activity for all three proposed landing area sites do not extend over the noise sensitive area identified in the Airport’s Fly Friendly Program. Lower levels of noise exposure (below 65 DNL) do extend over the noise sensitive area for each of the proposed sites. The noise analysis suggests that developing a helicopter landing area nearest the runway will reduce the levels of off-airport noise exposure associated with helicopter activity.

It should also be noted that this noise evaluation is limited to the helicopter operations that would be attributed to a new east side helicopter landing area. Overall airport noise exposure levels will be evaluated based on the preferred runway alternative and preferred east helicopter landing pad.



Noise Overview (General Information)

Noise is the most common negative impact associated with airports.” Noise is often defined simply as “unwanted sound.” However, sound is measurable, whereas noise is subjective. The relationship between measurable sound and human irritation is the key to understanding aircraft noise impact. A rating scale has been devised to relate sound to the sensitivity of the human ear. The A-weighted decibel scale (dBA) is measured on a “log” scale, by which is meant that for each increase in sound energy level by a factor of 10, there is a designated increase of 1 dBA. This system of measurement is used because the human ear functions over such an enormous range of sound energy impacts. At a psychological level, there is a rule of thumb that the human ear often “hears” an increase of 10 decibels as equivalent to a “doubling” of sound.

The challenge to evaluating noise impact lies in determining what amount and what kind of sound constitutes noise. The vast majority of people exposed to aircraft noise are not in danger of direct physical harm. However, much research on the effects of noise has led to several generally accepted conclusions:

• The effects of sound are cumulative; therefore, the duration of exposure must be included in any evaluation of noise.

• Noise can interfere with outdoor activities and other communication.

• Noise can disturb sleep, TV/radio listening, and relaxation.

• When community noise levels have reached sufficient intensity, community wide objection to the noise will likely occur.

Research has also found that individual responses to noise are difficult to predict.1 Some people are annoyed by perceptible noise events, while others show little concern over the most disruptive events. However, it is possible to predict the responses of large groups of people – i.e. communities. Consequently, community response, not individual response, has emerged as the prime index of aircraft noise measurement.

On the basis of the findings described above, a methodology has been devised to relate measurable sound from a variety of sources to community response. For aviation noise analysis, the FAA has determined that the cumulative noise energy exposure of individuals to noise resulting from aviation activities must be established in terms of yearly day/night average sound level (DNL) as FAA’s primary metric. The DNL methodology also includes a significant calculation penalty for each night flight. DNL levels are normally depicted as contours. These contours are generated from noise measurements

1 Beranek, Leo, Noise and Vibration Control, McGraw-Hill, 1971, pages ix-x.



processed by a FAA-approved computer noise model. They are superimposed on a map of the airport and its surrounding area. This map of noise contour levels is used to predict community response to the noise generated from aircraft using that airport. DNL has been adopted by the U. S. Environmental Protection Agency (EPA), the Department of Housing and Urban Development (HUD), and the Federal Aviation Administration (FAA) for use in evaluating noise impacts.

The basic unit in the computation of DNL is the sound exposure level (SEL). An SEL is computed by mathematically summing the dBA level for each second during which a noise event occurs. For example, the noise level of an aircraft might be recorded as it approaches, passes overhead, and then departs. The recorded noise level of each second of the noise event is then added logarithmically to compute the SEL. To provide a penalty for nighttime flights (considered to be between 10 PM and 7 AM), 10 dBA is added to each nighttime dBA measurement, second by second. Due to the mathematics of logarithms, this calculation penalty is equivalent to 10-day flights for each night flight.2

A DNL level is approximately equal to the average dBA level during a 24-hour period with a weighting for nighttime noise events. The main advantage of DNL is that it provides a common measure for a variety of different noise environments. The same DNL level can describe an area with very few high noise events as well as an area with many low-level events.

DNL levels are typically depicted as contours. Contours are an interpolation of noise levels drawn to connect all points of a constant level, which are derived from information processed by the FAA-approved computer noise model. They appear similar to topographical contours and are superimposed on a map of the airport and its surrounding area. It is this map of noise levels drawn about an airport, which is used to predict community response to the noise from aircraft using that airport. DNL mapping is best used for comparative purposes, rather than for providing absolute values. That is, valid comparisons can be made between scenarios as long as consistent assumptions and basic data are used for all calculations. It should be noted that a line drawn on a map by a computer does not imply that a particular noise condition exists on one side of the line and not on the other. These calculations can only be used for comparing average noise impacts, not precisely defining them relative to a specific location at a specific time.

2 Where Leq (“Equivalent Sound Level”) is the same measure as DNL without the night penalty incorporated, this can be shown through the

mathematical relationship of:

Leqd = 10 log ( Nd x 10 (SEL/10) )

86,400

If SEL equals the same measured sound exposure level for each computation, and if Nd = 10 daytime flights, and Nn = 1 night-time flight, then

use of a calculator shows that for any SEL value inserted, Leqd = Leqn.



Land Use Compatibility

Based on federal standards defined by FAR Part 150, residential development within the 65 DNL contour and above is not recommended and should be discouraged by local land use officials. Oregon’s airport noise and land use compatibility guidelines discourage residential development within the 55 DNL contour, although it is not prohibited. Oregon’s airport noise and land use compatibility planning guidelines (OAR 340-035-0045 - Noise Control Regulations for Airports) are included in the report appendix. The Oregon guidelines encourage efforts to avoid or mitigate potential noise impacts between 55 and 65 DNL, and provide more restrictive guidance consistent with federal standards for noise exposure levels 65 DNL and above.

Conceptual Helicopter Landside Facilities

Figure 6-5 depicts the proposed helicopter landing areas and conceptual landside development areas to accommodate helicopter parking and hangar development. The facility configurations for each site were developed to be compatible with the east landside development options presented in Chapter Seven. As a result, the selection of a preferred helicopter landing area and the east airport landside options are directly connected and require a coordinated development approach. The configurations for each site are intended to be conceptual and will be further refined based on preliminary evaluations.

The proposed helicopter facilities are generally located in areas that are not currently leased. However, a portion of Site C is located within a leased area; this location was previously identified in a previous helicopter development proposal.

Based on the long-term forecast demand for helicopter parking, the sites are configured to accommodate 20 to 22 helicopter parking positions with an adjacent area to accommodate fixed base operation (FBO), hangar facilities and vehicle parking.

The helicopter landing areas are configured with two pads, spaced 600 feet apart. The helicopter pads are aligned parallel to the runway to allow simultaneous (parallel) operations. As noted earlier, this is scaled down version of a similar helicopter landing area located at Hillsboro Airport that is designed to accommodate multiple helicopters during training operations. Paved taxiways connect the pads with the east parallel taxiway and adjacent helicopter parking areas.


Chapter 6 – Helicopter Landing Area Siting Analysis

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