The Boeing Bump Index (BBI)

Do you evaluate the Boeing Bump Index (BBI)?

The Boeing Bump Index (BBI) is a parameter introduced by Federal Aviation Administration (FAA) in the 2009 for the airport pavement roughness evaluation, specifically for runway.

Before that moment, all the main methods used for roughness evaluation were derived from the road sector and were not specifically developed based on the real needs of the aeronautical field, for this reason FAA tried to introduce new operative standard for the runway roughness. Usually, the concept associated to the road roughness level takes in consideration the level of comfort for passengers on board, this because the time spent on the road is quite relevant, despite of the airport case, where the time spent by passenger on the ground is short. For this reason, the thresholds associated to the roughness acceptance level are mostly associated to the safety of the aircraft (possibility of the pilot to clearly read the instrumentation or not properly control the airplane movements, etc).

In addition, the parameters developed for road roughness takes into consideration the profile wavelength affects to car movements, usually up to 40 m, but the car wheelbase is around 3 meters while an aircraft is around 20 meters. For this reason, the BBI calculation base-length is 120m, that means to consider wavelength over 200m.

As the name indicates, the Boeing Bump Index was originally developed by Boeing Commercial Aviation Company, and then adopted also from Federal Aviation Administration starting since 2009, incorporating in the Advisory Circular AC 150/5380-9.

The basis of the Boeing Bump method is to construct a virtual straightedge between two points on the longitudinal elevation profile of a runway and measure the deviation from the straightedge to the pavement surface (named “Bump Height”). The Boeing Bump procedure considers straightedge lengths (wavelengths) up to 120 meters (394 feet). Because the Boeing Bump procedure targets isolated bump events, “wavelength” terminology is replaced with “bump length”. Evaluate each combination of bump height and bump length allows to evaluate the pavement roughness condition:

  • Acceptable, the FAA expects newly constructed or rehabilitated pavement to result in bump height and length combinations that fall within the lower region of the acceptable range.
  • Excessive, the FAA encourages airport operators to repair pavements as roughness levels enter the excessive zone. Airplane response to excessive levels of roughness becomes noticeably intolerable to both airplane crews and passengers.
  • Unacceptable, roughness levels in the unacceptable zone warrant immediate closure of the affected pavement. Repairs are necessary to restore the pavement to an acceptable level.

Do you use the Boeing Bump Index as parameter in your airport, and if so, what tools do you use?

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