Airport planning, design and operations (l. 5-10)

Q: What is the difference between sound and noise?

Sound = objective pressure variation; Noise = sound judged unwanted (subjective; affects policy due to annoyance/sleep impacts).

Q: How is sound pressure level expressed and why use A-weighting?

SPL in dB (log scale). A-weighting (dBA) approximates human perceived loudness, used for community metrics.

Q: What is LA,max?

LA,max = A-weighted maximum sound level during a single event.

Q: What is SEL / LAE?

SEL (Sound Exposure Level) integrates the total acoustic energy of an event, normalized to a 1 second reference.

Q: What is EPNdB / LEPN used for?

EPNdB (Effective Perceived Noise in dB) is a certification metric incorporating tonal/impulsive corrections; used in aircraft noise certification.

Q: What is Lden (or LDN)?

Lden/LDN = day-evening-night long-term average (yearly) with evening/night penalties (night often +10 dB) used for policy and contouring.

Q: What is Lnight?

Lnight = average noise level during defined night hours; used for night restrictions and health assessments.

Q: What is the Dutch Noise Load B (NL)?

Noise Load B (NL) = a regional metric in the Netherlands based on LA,max; used locally for planning and limits.

Q: How do SEL and indoor SEL relate to health effects?

Higher SEL correlates with increased probability of awakenings and sleep disturbance; SEL is used to estimate sleep impacts.

Q: Main engine noise mechanisms for piston engines?

Piston: exhaust noise, rotational noise, and vortex shedding from cylinders/structural components.

Q: Main noise mechanisms for turboprops?

Turboprop: propeller rotational and vortex noise; notable high-frequency components and tonal characteristics.

Q: Main noise mechanisms for turbojet/turbofan?

Turbojet/turbofan: at high thrust jet exhaust dominates; at low thrust fan/rotor noise dominates. Higher bypass ratio → lower jet velocity → reduced jet noise.

Q: What are propfan/UHB concepts in terms of noise?

Propfan / Ultra-High-Bypass: fuel-efficient but can produce strong tonal noise and high acoustic signature.

Q: What airframe elements produce noise and when are they important?

Flaps, slats, landing gear, high-lift devices and wakes generate aerodynamic noise, especially during approach/landing and high flap settings.

Q: How does the relative contribution from engine vs airframe vary by flight phase?

Takeoff/climb = engine (jet/fan) dominant; initial climb/acceleration = engine dominant; approach/landing = airframe dominant (with some engine); ground ops = APU/taxi/run-ups dominate.

Q: What is the SAE AIR 1845 / NPD concept used for?

SAE AIR 1845 provides procedures and Noise Power Distance (NPD) tables — empirical noise levels vs distance used as the base for segment noise calculations.

Q: Outline the INM single-event workflow in brief.

Flight path broken into straight segments → read NPD for each segment → apply speed/lateral/atmospheric adjustments → convert to SEL at observer → sum segments to get single-event SEL → aggregate events for cumulative metrics.

Q: What key inputs are required for INM/segment modelling?

Aircraft type & thrust, track geometry, altitudes, speeds, number of operations, and ground/terrain/atmosphere assumptions.

Q: What receiver layout is used to produce contour maps in INM?

An evenly spaced observer grid of receiver points covering the study area; contour values interpolated from grid.

Q: Name important model adjustments applied to NPD/SEL values.

Lateral attenuation, slant range corrections, atmospheric absorption/ground effects, and tone/weighting corrections.

Q: How are single-event SELs combined into Lden?

Convert SEL to equivalent energy contributions over time, sum energy from all events, then convert back to dB and apply day/evening/night penalties to compute Lden.

Q: What does ICAO Annex 16 cover?

International aircraft noise certification standards, metrics and limits; CAEP manages technical revisions and standards evolution.

Q: Why does choice of metric (Lden vs Lmax vs EPNdB) matter for policy?

Different metrics emphasize single-event peak vs cumulative exposure vs certification characteristics, which changes which operations or areas are regulated and who is affected.

Q: List common policy/operational levers airports use to reduce noise exposure.

Night quotas/curfews, differential noise charges, preferential runway use/routing, operating bans, slot management, insulation/land use planning.

Q: Key elements of Schiphol’s policy framework to remember.

Move from enforcement point system to Alders Tafel: caps on total flights, night flight limits, constraints on population/housing within LDEN/Lnight contours, promotion of CDA and mitigation investments.

Q: Name aircraft-level mitigation measures and their trade-offs.

Quieter engines, higher bypass ratios, airframe noise reduction, fleet renewal. Trade-off: long lead times, high cost, may impact weight/fuel trade-offs.

Q: Name operational-level mitigation measures and main trade-offs.

Noise abatement procedures (CDA), RNAV noise-optimized SIDs, climb profiles, displaced thresholds, APU limits, differential charges. Trade-offs: may shift noise footprints, change fuel burn or safety margins.

Q: Name airport design & planning measures and trade-offs.

Runway placement, high-speed exits, sound barriers, land-use zoning, insulation programs. Trade-offs: cost, planning constraints, possible environmental impacts.

Q: What community health impacts link to aircraft noise?

Stress, elevated blood pressure, sleep disturbance (awakenings), cognitive/learning impacts in children, annoyance, property value loss.

Q: Why can procedural noise reductions still leave overall exposure high?

Operational growth (more movements) can offset per-movement noise reductions; procedural changes can reduce annoyance for some but increase it for others (redistribution).

Q: Quick INM memorization line (exam-ready).

NPD tables → segment adjustments → SEL per event → sum events → compute Lden/contours.

Q: Quick dB/log rule reminder for exam calculations.

dB are logarithmic: small dB differences are perceptible but represent large energy changes; combine energies not dB values directly.

Q: What should you list under “Mitigation hierarchy” in a short answer?

Aircraft (tech), Operational (procedural), Airport design & planning, Economic instruments.

Q: Which metric would you cite when asked about nighttime policy?

Lnight (and Lden for overall policy because of night penalties).

Q: How does higher bypass ratio affect community noise?

Higher bypass ratio reduces jet velocity and thus reduces jet noise (noting fan/other sources still matter).

Q: What are the main pollutants from jet fuel combustion?

CO2, H2O, NOx, CO, HC/UHC, SOx, particulates/soot, VOCs.

Q: What is an Emission Index (EI)?

EI = grams of pollutant per kg of fuel burned (g/kg fuel); used to convert fuel burned into pollutant mass.

Q: Typical EI values for CO2 and H2O per kg fuel?

CO2 ≈ 3150 g/kg fuel; H2O ≈ 1250 g/kg fuel.

Q: How do EIs vary with thrust setting?

CO and UHC/soot peak at low thrust/idle (incomplete combustion); NOx peaks at high thrust (high temperature/pressure).

Q: Which LTO modes and times does ICAO define for inventories?

Takeoff 100% thrust 42 s; Climb 85% thrust 132 s; Approach 30% thrust 240 s; Taxi/idle 7% thrust 1560 s.

Q: How do you compute emissions per LTO for one engine?

Use EI (g/kg) × fuel burned in mode (kg) for each mode, sum modes for LTO total per engine.

Q: How do you scale engine LTO emissions to airport inventory?

Multiply per-engine LTO emissions by number of engines per aircraft, number of operations, then sum across aircraft types and add ground sources.

Q: What other sources are included in an airport emission inventory?

GSE/APU, road vehicles, heating, fuel storage, de icing, maintenance activities, emergency training fires.

Q: Typical units reported for inventories?

Tonnes per year (or kg/year for detailed reporting).

Q: What determines local air quality impacts from aviation?

Pollutant concentrations below the mixing altitude (~3,000 ft) (PM, NO2, CO), local emissions rates, and dispersion conditions.

Q: Which pollutants are primary local air quality concerns near airports?

PM2.5/PM10, NO2, CO, SO2, O3 (secondary).

Q: What drives global climate impacts from aviation?

CO2 (long-lived) plus non CO2 effects: NOx→O3/CH4 changes, contrails and induced cirrus, aerosols/soot; all alter radiative forcing.

Q: How can contrails and contrail-induced cirrus affect climate?

They produce radiative forcing (net warming or cooling depending on conditions) and can be comparable to or larger than CO2 forcing per flight in some studies.

Q: What is the stratospheric NOx effect?

NOx emitted in the stratosphere catalytically destroys ozone, affecting ozone concentrations and radiative balance.

Q: Name three major policy instruments addressing aviation emissions.

ICAO Annex 16 (certification limits), EU ETS (cap-and-trade), ICAO CORSIA (global MBM with offsets).

Q: What does ICAO CORSIA aim to do?

Stabilize international aviation CO2 emissions growth by requiring airlines to offset growth above a baseline using approved offset units.

Q: Give examples of operational mitigation measures at airports.

Limit APU use, electric GSE, tow in/tow out, optimize taxi routing, reduce taxi delays, emission based fees, NOx optimized trajectories below 3,000 ft.

Q: Give examples of technological mitigation measures on aircraft.

Engine design improvements, higher bypass ratios, hybrid-electric and electric propulsion, improved combustors, lower-emission combustor technologies.

Q: What are common sustainable aviation fuel (SAF) pathways and considerations?

HEFA, Fischer Tropsch (FT), Hydroprocessed Renewable Jet (HRJ); lifecycle gCO2e/MJ varies widely and supply/land use constraints matter.

Q: Example lifecycle gCO2e/MJ figures (order of magnitude differences).

Crude-to-jet ≈ 87.5; algae oil ≈ 50.7; jatropha ≈ 39.4; switchgrass + FT/HRJ ≈ 17.7 (illustrative ranges, lifecycle dependent).

Q: What airport-level air quality measures reduce emissions and exposure?

Air quality monitoring, taxiway design to minimize idling, engine-runup restrictions, de-icing fluid capture, GSE electrification, water/waste management, insulation and land-use planning.

Q: Inventory calculation workflow (practical steps)?

Obtain per-aircraft/engine EI and fuel flow by LTO mode → compute emissions per LTO → multiply by operations → add ground/mobile sources → run dispersion to estimate concentrations → compare to standards.

Q: What trade-offs occur when optimizing for NOx vs fuel burn?

NOx-minimizing trajectories may increase fuel burn (more CO2) and vice versa.

Q: How can noise abatement procedures affect air quality and emissions?

They can shift pollutant footprints (concentrating emissions elsewhere), sometimes increasing fuel burn or ground-level exposure for different communities.

Q: How does electrification change local vs global impacts?

Electrification reduces local emissions (NOx, PM, CO) at airport; global benefit depends on electricity lifecycle carbon intensity; battery limits constrain range/payload today.

Q: Quick formula for computing a simple LTO emission (exam answer form).

EI (g/kg) × fuel burned per mode (kg) × engines × operations = grams per period → convert to tonnes/year.

Q: Which altitude defines the approximate mixing layer separating local and cruise impacts?

Mixing altitude ≈ 3,000 ft (approximate threshold for local dispersion relevance).

Q: Why is lifecycle analysis important for alternative fuels?

Because well-to-wheel or well-to-jet lifecycle emissions determine true climate benefit; production, feedstock, land use change, and CCS alter gCO2e/MJ.

Q: Which pollutants peak during ground/idle operations?

CO and UHC (and soot) peak at idle/ground due to incomplete combustion and low temperature.

Q: Name key reporting and database resources used for engine-mode EIs (exam understanding).

Engine emission databanks and manufacturer measured tables provide per-mode fuel flows and EIs used in calculations.

Q: What are the main market effects of airline deregulation?

Network reorganisation (hub-and-spoke), flexible pricing, frequent-flyer programmes, emergence of LCCs and cargo specialists, higher frequencies at hubs, larger aircraft and load factors, lower unit costs, greater market volatility.

Q: How does hub concentration change airline and passenger metrics?

Raises flight frequencies and load factors, encourages use of larger aircraft, reduces airline unit costs but can sometimes lower average origin-to-origin speed due to connections.

Q: What are the tensions between deregulation and airport capital planning?

Deregulation enables rapid market adjustments and volatility that can conflict with airports’ long-term, lumpy investment cycles and financing plans.

Q: Typical privatization trends in airports?

Increased private participation, outsourcing of operations, stronger focus on non-aeronautical revenue and commercial ventures, while retaining regulatory safeguards for prices, access and long-term development.

Q: Main ownership types for airports?

National (central government), regional/local, corporate (state-owned enterprises), and private investors.

Q: Common operator arrangements?

Fully government-run; public ownership with private operation (regulated control/management contracts); public–private partnerships; fully private ownership.

Q: Key tradeoffs between public and private ownership?

Public ownership can suffer inefficiency at scale; private ownership can improve commercial performance but requires public oversight on pricing, access and long-term planning.

Q: What are the three revenue categories for airports?

Aeronautical (charges to airlines), non-aeronautical (retail, parking, property, fuel), and non-operating (consultancy, equity in ventures).

Q: Examples of aeronautical charges and how they are measured?

Landing/takeoff fees (often MTOW-based), terminal charges (per passenger), parking, cargo, security, noise/emissions surcharges; formulas often use MTOW or per-passenger units.

Q: What are typical non-aeronautical revenue streams and why are they important?

Retail concessions, car parking, rental cars, property leases, advertising and fuel concessions; they are growing, often highly profitable and can subsidize aeronautical costs.

Q: ICAO charging principles in brief?

Users should pay a fair share of full costs (operating, depreciation, interest, maintenance) but not more; charges must be non-discriminatory, transparent and published.

Q: What is single till regulation?

Regulator treats aeronautical and non-aeronautical revenues together when setting aeronautical price caps so non-aeronautical profits can lower aeronautical charges.

Q: What is dual till regulation?

Aeronautical and non-aeronautical revenues are treated separately; aeronautical charges are set to recover aeronautical costs only, leaving commercial profits to the airport.

Q: Residual versus compensatory costing — what’s the difference?

Residual: aeronautical charges make up the residual after non-aeronautical revenues (airlines take more risk). Compensatory: aeronautical charges recover actual aeronautical costs (airport bears more risk).

Q: Common regulatory tools used to control airport pricing and service?

Price caps (e.g., RPI − X), periodic regulatory reviews, performance/level-of-service penalties, and formal consultation with carriers.

Q: What does a life cycle cost model for an airport project include?

R&D/design, capital investment (CAPEX), operations & maintenance (OPEX), and termination/disposal costs; typical evaluation horizons are long (e.g., 20 years).

Q: Key project appraisal metrics and decision rules?

NPV — accept if NPV > 0; IRR — accept if IRR > cost of capital; decision trees/expected value analysis for uncertain demand.

Q: Typical cash-flow profile of airport projects?

Capital intensive with lumpy CAPEX peaks, long payback periods (often >15–20 years), and revenues ramping up over time.

Q: Main financing sources for airport capital?

Government grants (AIP), special taxes, development bank loans, operating surpluses, commercial loans, general obligation bonds, revenue bonds, passenger facility charges (PFCs), and private finance/BOT/PFI arrangements.

Q: How can decision trees help in terminal sizing under uncertainty?

They map possible demand scenarios, attach probabilities and payoffs to each branch, calculate expected values and identify options (e.g., phased expansion) that maximise expected NPV or minimise downside risk.

Q: What are the three main subdivisions of ATM?

Air Traffic Flow Management (ATFM), Air Traffic Services (ATS), and Airspace Management.

Q: What is the aim of ATFM?

To match traffic demand with available capacity through prediction, strategy development, and implementation of measures.

Q: What are the three core steps in the ATFM process?

Predict potential overloads, develop strategies (e.g., ground holding, rerouting, metering), implement measures operationally.

Q: What time horizons does ATFM cover?

From months (strategic planning) down to around 30 minutes (tactical measures).

Q: How is ATFM coordinated in Europe?

Centrally by Eurocontrol’s flow management unit (CFMU).

Q: What does Flight Information Service (FIS) provide?

Operational safety information such as SIGMET/AIRMET, volcanic and other hazards.

Q: What is the function of Alerting Service (ALS)?

To initiate search and rescue (SAR) and notify emergency responders when an aircraft is in distress.

Q: What is the Aeronautical Telecommunication Network (ATN)?

The network that handles air-ground and ground-ground digital communications for ATM.

Q: What do AIS and MET provide?

AIS publishes aeronautical operational data; MET provides meteorological services and forecasts.

Q: Core responsibilities of Air Traffic Control (ATC)?

Maintain separation, issue clearances (voice and data link), manage tactical sequencing, and coordinate handovers between sectors.

Q: What is a Flight Information Region (FIR)?

A defined block of airspace for which a specific authority provides flight information and alerting services.

Q: How is an FIR typically organised for control?

Segmented into sectors, each staffed by controller teams responsible for a specific traffic volume/route structure.

Q: Roles of Tower, TRACON/APP, and ACC/ARTCC?

Tower handles ground and runway control; TRACON/APP manages departure/arrival sequencing and terminal area; ACC/ARTCC handles en route control across large airspace.

Q: What is MUAC and what does it do?

Maastricht Upper Area Control — manages upper airspace (e.g., >FL245) for busy European flows and coordinates cross-border traffic.