National Academies Press: OpenBook

Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping (2009)

Chapter: Appendix E: Algorithms Employed in the Processing of the European FDR Data

« Previous: Appendix D: EDMS Modeling of Airside Operations
Page 133
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 133
Page 134
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 134
Page 135
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 135
Page 136
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 136
Page 137
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 137
Page 138
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 138
Page 139
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 139
Page 140
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 140
Page 141
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 141
Page 142
Suggested Citation:"Appendix E: Algorithms Employed in the Processing of the European FDR Data." National Academies of Sciences, Engineering, and Medicine. 2009. Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping. Washington, DC: The National Academies Press. doi: 10.17226/22992.
×
Page 142

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

E-1 Appendix E. Algori thms Employed in the Processing of the European FDR Data A query-based analysis was developed by Wyle and executed by Volpe on a dataset containing detailed flight data recorder data from 2359 commercial flight operations (aircraft startup to shut down) from a major European Airline. The aircraft types represented in this database are listed in Table E-1. Table E-1. European Airline Fleet Summary Aircraft Engines Engine UID A319-112 CFM56-5B6/2P 3CM022 A320-214 CFM56-5B4/2P 3CM021 A321-111 CFM56-5B1/2P 3CM020 A330-223 (old; ver 9S) P&W 4168A 4PW067 A330-243 (old version) RR Trent 772B-60/16 2RR023 A340-313 CFM56-5C4 2CM015 757-200 RR (757-3) RR RB211-535E4 3RR028 A330-202 GE CF6-80E1A4 4GE081 A330-243 RR Trent 772B-60/16 3RR030 767-300 GE (767-3A) GE CF6-80C2B7F 2GE055 777-3FXER GE (D01) GE90-115B1 7GE099 A340-541 RR Trent 553 ARJ100 (DAR 512) LF507-1F 1TL004 ARJ85 (DAR 512) LF507-1F 1TL004 Analysis differentiated between taxi operations for departing and arriving aircraft. Query results include assessment of the parameters listed below for each aircraft and operation type. • Engine usage when moving and stationary • Average and standard deviation of thrust while moving and stationary • Breakaway Thrust for operations where it could be successfully identified • Average and standard deviation of groundspeed while moving • Average and standard deviation of lateral and longitudinal acceleration • Assessment of the frequency of rolling takeoffs versus non-rolling takeoffs • Amount of time spent idling / running up before takeoff movement begins E.1 . F l ight Segment Pars ing To develop the summary data, the flight record was split into operational segments for the entire flight from gate to gate: departure, enroute flight and arrival. This included segments such as parked at the gate, pushback, taxi to the runway (including any holding queues encountered), and departure operation on the runway. On ground FDR data is spaced 5 seconds apart. The departure segment was further examined and aircraft with “rolling departures” were separated from those who “held” at the end of the runway before departing. The next segment was the runway takeoff, followed by the enroute flight segment. At the destination region, the records were split up to include approach up to the touchdown point along with the runway deceleration period. A segment where the aircraft had left the runway and was on a taxiway (regardless of speed) was included arrival taxi segment. The aircraft at the gate was considered part of the taxi segment up until the time when the fuel flow was reported as zero for all engines. Operations at the gate while engines were spooling down (and thrust

E-2 / operating state parameters were reported as non-zero) were not included in the taxi segment. Subsequent examination of the average operational parameters for stationary portions (or holds) included this stationary gate portion of the taxi operation. The departure taxi segment and the arrival taxi segments were assessed separately. An assessment of the use of engines expressed as a function of total taxi time was performed in order to determine whether single or multiple engine operations could be a factor in taxi analysis. Stationary segments were defined as those with reported ground speed less than 1 knot and moving segments those with speeds at or above 1 knot. During these stationary and moving segments average ground speed and thrust parameters were obtained from the FDR data. One would expect that taxi speeds immediately after leaving the runway on arrivals to be greater than those for departing aircraft as is indicated in the average and standard deviation of ground speed (Table 2-1). Table 2-2 itemizes the average and standard deviation of ground speed for both moving and stationary segments during departure and arrival taxi operations. The engine operating state parameters as reported in the FDR data is presented in Table 2-3. The following description of the meaning and units of the engine operating state parameters are as follows: • N1avg: N1, average (all engines, percent of maximum) at start of event • %Thrust: percent of maximum thrust at start of event • EMS Thrust: EMS thrust per engine, averaged over all engines at start of event, lbs • EMS enhanced: EMS enhanced thrust per engine, averaged over all engines at start of event, lbs To be considered moving, the aircraft FDR recorded groundspeed exceeded 1 knot. Groundspeeds of 1 knot or lower indicated a stationary aircraft. This 1 knot threshold was selected based on a visual assessment of raw data while considering the acceleration, thrust, latitude and longitude along with other parameters in conjunction. Initial attempts to solely use groundspeed = 0 to identify a stationary aircraft, as we had in the past, was an inaccurate way to identify the state. The first attempt at obtaining average engine thrust settings yielded suspiciously low values. Upon closer inspection it was determined that those computations included many records where the aircraft was parked at the gate and the engines were slowly winding down after being shut down. This necessitated the creation of a filter to ignore any data points where the total fuel flow was zero. Due to licensing restrictions the full FDR dataset could not be accessed directly by Wyle engineers. While ultimately successful, development of the data queries and macro algorithms was problematic due to the inability for our engineers to actually “see” the raw FDR data other than a few sample flight operations. As is common when working with real data (as opposed to simulated data) a variety of unexpected situations were encountered which necessitated modification of the algorithms. Examples of this included data drop-outs, uncalibrated accelerometer sensors, inconsistent file formatting in occasional FDR files, bad data fields, extended taxi periods with groundspeed values like 0.125 and 0.0625 knots, (which effectively should be zero) and records with negative Percent Thrust values, and negative EMS Thrust values. E.2 . Descr ip t ion of the Tax i Hold Processor The ground taxi processor is a macro written in Visual Basic contained within an Excel workbook. The input parameters are specified as lines on the "Input" sheet of this workbook. The input parameters specify the input file path and name, output file path and name, arrival/departure indicator ("A" or "D"), groundspeed cutoff threshold (specifies what groundspeed qualifies as a moving aircraft; groundspeed is often 0.25 or 0.5 knots ), and the acceleration threshold (used to isolate actual acceleration/deceleration from what is apparently accelerometer background noise).

E-3 The macro processes each input file, one at a time. It first opens the input file, forcing it to a specific .CSV format, saves it in that format, and then reads the entire input file into memory, storing it in an array. The departure segment (called "Segment 0", from the beginning of the flight until the aircraft is accelerating on the runway for takeoff) and the arrival segment (called "Segment 9", from the time the aircraft leaves the runway after touchdown until it is parked at the gate) were previously parsed into separate files. For the initial processing of a file, the program must determine the nature of the data at the end of the file to process it accordingly. If the specified input file is an arrival, processing starts at the last line of data and moves toward the beginning, ignoring all records until reaching the first record that has a Total Fuel Flow that is non- zero. This process was incorporated to properly process files in which after parking at the gate, the data recorder continued to record data after the fuel flow moved to zero, while the engines were winding down to zero rpm or after they had reached zero rpm. If the specified input file is a departure, processing starts from the last line of data, which represents the last data before the aircraft has begun the takeoff roll. If the last or second-to-last record has a groundspeed lower than Groundspeed Threshold parameter, the flight is considered to be a non- rolling departure, and the time of the last record is considered to be the end point of a hold. A "hold" is defined as any period in which the groundspeed is less than the specified Groundspeed Threshold. A threshold of 1 knot was used for this analysis. If the flight is a non-rolling departure, program execution steps backward through the data until a record is found with a groundspeed above the Groundspeed Threshold. At this point the program calculates the hold time and reports all output parameters for this hold (except acceleration-related ones) to the output file. Execution then works backwards, continuing through the rest of the input file to the beginning, finding ending points and starting points for all other holds, calculating all output parameters except acceleration-related ones. Additionally, at the end of every hold other than the on-runway hold which occurs in a non-rolling takeoff, an acceleration period is determined and output parameters are calculated. The acceleration period includes the subsequent records, following the end of the hold, which meet the acceleration criteria. To meet the acceleration criteria, the Longitudinal Acceleration + Acceleration Offset must be greater than the Acceleration Threshold specified in the input parameters on the spreadsheet’s INPUT sheet. For processing, a value of -0.001 was used. The Acceleration Offset is a calculated parameter that was introduced into the process because there were signs of positive or negative bias in the longitudinal acceleration values of many flights. The Acceleration Offset for a given flight is calculated by taking the opposite of the arithmetic mean of the acceleration values that occur when the groundspeed is below a threshold that is specified as an input parameter on the spreadsheet’s INPUT sheet. For processing, a value of 0.25 knots was used for the groundspeed threshold for acceleration offset calculation. After the start point, end point, acceleration period and all associated output parameters have been calculated for a given hold, all output parameters are written as a line in the output file. After the entire input file has been processed, the program continues on to the next line of input found on the “Input” worksheet until all lines have been processed. E.3 . Accelerat ion a f ter a Hold Event Attempts to determine aircraft acceleration after a hold event (longitudinal acceleration) also highlighted difficulties with solely using SQL queries for dataset interrogation. Acceleration data

E-4 results included bias in the FDR data, clear indications of stationary aircraft (evidenced by zero ground speed) yet with non-zero accelerations in both the lateral and longitudinal directions, as well as some instances where the acceleration data just did not make sense. The acceleration bias can be seen in a few sample flight tracks in the acceleration levels in G loads for a B767 longitudinal acceleration (Figure E-1) and in the lateral acceleration for the A319 (Figure E-2). This bias explains some of the erroneous query results from the first round of analysis – namely average speeds obtained during intervals with no acceleration were in essence derived from only a few data points rather than as intended, being a representative sample of the operational state. Based on examination of numerous flight tracks a threshold of +/- 0.02G was implemented in the analysis for differentiating between acceleration and steady motion. Prior queries with a 0.G threshold indicated that virtually no data points were present in the entire dataset. 767 Taxi Segment Longitudinal Acceleration -0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0 50 100 150 200 250 300 Point Lo ng itu di na l A cc el er at io n (G ) Flight 1 Flight 2 Flight 3 Flight 4 Flight 5 Flight 6 Figure E-1: B767 Longitudinal Acceleration (g) A319 Lateral Acceleration -0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 0 50 100 150 200 250 300 350 point # A cc el er at io n (G ) Series1 Series2 Series3 Series4 Series5 Series6 Series7 Figure E-2: A319 Longitudinal Acceleration (g)

E-5 E.4 . Thrust dur ing Accelerat ion a f ter a Hold Event A hold was defined as any period during which the aircraft speed (as reported by the ground speed indicator in the FDR data) was less than 1 knot. The cause of the hold (wait to cross a runway, queue hold due to traffic, hold after pushback etc…) could not be determined or catalogued. The Maximum Thrust was determined by searching through the time records during the stationary period immediately preceding the acceleration event, and extracting the maximum value of the indicated Thrust parameter. It is presumed that these particular acceleration events are due to the application of breakaway thrust and hence a significantly higher, yet shorter duration acceleration region than those other events with very low values of acceleration (less than .05 g) which tend to linger for long times. The resolution of the source FDR files used in this analysis all contained a 5 second time spacing hence the discrete time intervals in the figures in this section. The following description of the meaning and units of the engine operating state parameters are as follows: • N1avg: N1, average (all engines, percent of maximum) at start of event • %Thrust: percent of maximum thrust at start of event • EMS Thrust: EMS thrust per engine, averaged over all engines at start of event, lbs • EMS enhanced: EMS enhanced thrust per engine, averaged over all engines at start of event, lbs The following series of Figures E-3 through Figure E-13 display the Maximum % Thrust extracted from the FDR data from the time period immediately preceding and including those acceleration events which follow a hold. Acceleration Events following a Hold - All Aircraft Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A319-Arri A319-Depa A320-Arri A320-Depa A321-Arri A321-Depa A330-Arri A330-Depa A340-Arri A340-Depa B757-Arri B757-Depa B767-Arri B767-Depa B777-Arri B777-Depa Figure E-3: Acceleration Event (Maximum % Thrust) following a Hold, All Aircraft

E-6 Acceleration Events following a Hold - All Aircraft, Departures Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A319-Depa A320-Depa A321-Depa A330-Depa A340-Depa B757-Depa B767-Depa B777-Depa Figure E-4: Acceleration Event (Maximum % Thrust) following a Hold, Departures Acceleration Events following a Hold - All Aircraft, Arrivals Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A319-Arri A320-Arri A321-Arri A330-Arri A340-Arri B757-Arri B767-Arri B777-Arri Figure E-5: Acceleration Event (Maximum % Thrust) following a Hold, Arrivals

E-7 Acceleration Event following a Hold - A319 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A319-Arri A319-Depa Figure E-6: Acceleration Event (Maximum % Thrust) following a Hold, A319 Acceleration Event following a Hold - A320 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A320-Arri A320-Depa Figure E-7: Acceleration Event (Maximum % Thrust) following a Hold, A320

E-8 Acceleration Event following a Hold - A321 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A321-Arri A321-Depa Figure E-8: Acceleration Event (Maximum % Thrust) following a Hold, A321 Acceleration Event following a Hold - A330 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A330-Arri A330-Depa Figure E-9: Acceleration Event (Maximum % Thrust) following a Hold, A330

E-9 Acceleration Event following a Hold - A340 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) A340-Arri A340-Depa Figure E-10: Acceleration Event (Maximum % Thrust) following a Hold, A340 Acceleration Events following a Hold - B757 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) B757-Arri B757-Depa Figure E-11: Acceleration Event (Maximum % Thrust) following a Hold, B757

E-10 Acceleration Events following a Hold - B767 Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % ) B767-Arri B767-Depa Figure E-12: Acceleration Event (Maximum % Thrust) following a Hold, B767 Acceleration Events following a Hold - All Aircraft Maximum thrust (%) as a function of Acceleration Time (sec) 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Accel Time (sec) M ax T hr us t ( % )M ax L on g A cc el (g ) B777-Arri B777-Depa Figure E-13: Acceleration Event (Maximum % Thrust) following a Hold, B777

Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s Airport Cooperative Research Program (ACRP) Web-Only Document 9: Enhanced Modeling of Aircraft Taxiway Noise, Volume 1: Scoping explores ways to model airport noise from aircraft taxi operations and examines a plan for implementation of a taxi noise prediction capability into the Federal Aviation Administration's integrated noise model in the short term and into its aviation environmental design tool in the longer term.

ACRP Web-Only Document 9: Enhanced Modeling of Aircraft Taxiway Noise, Volume 2: Aircraft Taxi Noise Database and Development Process documents the procedures developed and employed in the creation of a taxi noise database for the U.S. Federal Aviation Administration’s Integrated Noise Model and Aviation Environmental Design Tool (AEDT). The AEDT is currently under development.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!