As airports approach the limits of their runway systems, increasing capacity through infrastructure expansion is not always feasible due to economic, environmental, and operational constraints. Consequently, there is growing interest in operational measures that improve the use of existing infrastructure. Two such concepts are Time-Based Separation (TBS), which reduces the loss of arrival capacity due to headwinds by dynamically adjusting separations, and RECAT-EU-PWS, which refines wake turbulence separation minima through a more detailed pairwise categorisation scheme. However, no openly available macro-level analysis currently evaluate the capacity gains associated with these concepts across different airport environments and operating conditions.

This thesis investigates to what extent the implementation of TBS and RECAT-EU-PWS can increase airport peak runway capacity. To address this question, ARCAS (Airport Runway Capacity Assessment Software) was developed as a discrete-event simulation model in Python. The model builds on previous runway dependency logic and was implemented in a flexible and modular framework capable of representing multiple runway configurations, traffic mixes, weather conditions, and separation schemes. Embedded within a Monte Carlo approach, ARCAS estimates peak capacity, generates capacity envelopes, and evaluates the effects of TBS and RECAT-EU-PWS under a range of representative scenarios.

The model was applied to several Spanish airport case studies representing single mixed, parallel segregated, intersecting, and converging/diverging runway systems. Verification and validation showed that the model provides a credible macro-level representation of runway performance, with Monte Carlo estimates stabilising at around 500 runs and peak-capacity deviations of up to 2% in when compared to other runway capacity models.

The results show that runway capacity is limited by different dominant bottlenecks depending on runway configuration. In single mixed and parallel segregated runways, the main drivers are traffic composition and weather, with the proportion of heavy aircraft emerging as the most significant source of capacity loss and headwind also exerting a strong influence. In intersecting and converging runway systems, by contrast, the dominant constraints are runway geometry and runway-blocking constraints. TBS was found to be technically beneficial only above configuration dependent headwind thresholds, with meaningful gains appearing at approximately 12 kts for single mixed runways, 4 kt for parallel segregated systems, 15 kts for intersecting layouts, and 25 kts for converging layouts. RECAT-EU-PWS likewise showed scenario specific effects: in single mixed operations, gains were observed across the entire analysed range of heavy aircraft shares, while in parallel segregated, intersecting, and converging layouts, meaningful benefits emerged only above heavy-aircraft shares of approximately 11%, 5%, and 5%, respectively.

A limitation of this work is that the analysis is intentionally restricted to a macro-level, runway-centred assessment of TBS and RECAT-EU-PWS. The current framework adopts a fixed categorical implementation of the 20-category wake turbulence scheme, does not explicitly represent complementary concepts such as ROCAT, and considers meteorological effects mainly through headwind conditions in the application of TBS. In addition, the model evaluates runway throughput once aircraft are already established in the approach stream, without accounting for upstream sequencing concepts such as Point Merge. The case-study validation is also limited to several Spanish airports, which can constrain the generalisation of the results, particularly for the intersecting-runway case where the selected scenario is not fully representative of typical operations. Finally, although the datasets used are of generally high quality, some parameters, such as departure runway occupancy times and departure speed profiles, had to be derived from previous work rather than obtained directly from local operational data. ... Read more

This report entails the design of a regional passenger aircraft, serving 48 passengers and entering the market by 2035. It is known as the SRP-22 ALAR FOX, however, in general, SRP-22 is used. The propulsion system is designed with hydrogen as its fuel. The hydrogen is converted to electricity with a low-temperature proton-exchange membrane fuel cell, which in turn is used by the electric motors, to power the propellers. There are four electric motors with one six-bladed propeller each. Two propellers are located under the wing near the fuselage and deliver 80% of the total power. The remaining two propellers are positioned on the wing tips, delivering the remaining 20%. The benefit of these wingtip propellers is an expected drag reduction of around 10%, due to the attenuation of wingtip vortices.
The hydrogen is stored in a composite tank, located behind the aft pressure bulkhead. The fuel cell is placed under the cabin floor, just in front of the pressure bulkhead, such that less tubing is required to transport the hydrogen. The boil-off of the hydrogen is used to transform the hydrogen from its liquid state to its gaseous state, through the usage of glass rods. After that, the hydrogen is heated up until about 80◦C, which is the operating temperature of the fuel cell. The control system is controlled through a mechanical-powered hydraulic system. The elevator design includes horns to relieve the hinge moment.
One of the main goals was to reduce the environmental impact of the aircraft. The average temperature response of the SRP-22 is almost 83 times lower than that of the ATR 42 by 2064, which supports this goal. Noise has also been taken into account, which mainly stems from the propellers and airframe. It is found that the noise levels are well below the limits set by ICAO. The unit list price of the SRP-22 will be $19 million when using more optimistic fuel cell prices, while a least optimistic estimate results in a unit list price of $37 million. Moreover, the direct operational cost is around 10% lower than those of the ATR 72. Because of the usage of electric motors, the maintenance cost is expected to be lower than for a turboprop aircraft. ... Read more