Influence of Airspeed Measurement Error – Implications for Dead Reckoning Navigation

Errors in navigational instruments can significantly affect flight safety. Airspeed is a key piece of navigational data that depends on accurately measured air pressure, which in turn depends on accurately measured air temperature. Instead of measuring the outside air temperature in real time, cockpit instruments are preprogramed with standard air temperature values for different flight altitudes, but atmospheric conditions can cause the actual temperature to deviate substantially from these standard values. In the present study, test flights were conducted under various atmospheric conditions to examine how the actual temperature affects the deviation of the actual airspeed from the measured airspeed. Results indicate that the differences between the actual and the standard temperature, and not those between the actual and the standard pressure, are the primary cause of deviations of the measured from the actual airspeed. The results of this study may help establish aircraft flight models based on more accurate estimates of navigational parameters

Operational Aspects of Vertical Navigation during the Approach Phase of Flight: CDA vs. Conventional Step-Down Approach

The continuous descent approach (CDA) is an operational technique used by aircraft when descending from cruise altitude; the aim is to minimize thrust and thereby avoid horizontal flight segments. CDA involves vertical navigation calculations that modify flight trajectory according to altitude; these procedures can reduce fuel consumption, emission of toxic exhaust gases, and noise due to the aircraft and its engines. In order to verify some of these benefits under field conditions in Croatia, the present study analysed fuel consumption, approach distance and approach duration during 44 landings by Croatia Airlines Dash-8 Q400 aircraft at the airport in Split, Croatia. CDA was performed at 426 km/h (230 knots) or at high speed, and these procedures were compared with the standard step-down approach involving a flight speed of 426 km/h (230 knots) and an18.5 km-long (10 NM) horizontal segment at an altitude of 914 m(3000 ft). The different approach conditions were compared in terms of fuel consumption. The results indicate that implementing CDA can provide small fuel savings on individual flights, and that these savings can be significant when calculated over an entire fleet on an annual basis. The significant reduction in fuel consumption should also mean a reduction in CO2 emissions

Development, Design and Flight Test Evaluation of Continuous Descent Approach Procedure in FIR Zagreb

As part of Local Conversion and Implementation Plan which is based on the EUROCONTROL Revised Convention the Republic of Croatia has undertaken to make a plan of implementing the Basic Continuous Descent Approach procedures. This paper addresses the issue of navigational path optimization for the A-319/320 commercial aircraft within the fleet of Croatia Airlines, during the approach part of flight, which has a positive effect on fuel consumption, greenhouse gas emission and area of surface affected by noise. The experiments were carried out in real conditions, using internal sensors onboard (Flight Data Recorder) and independent GPS system. Two types of approach were tested: Continuous Descent Approach (CDA) and Step Down Approach. The implementation of CDA procedures, just for the fleet of Airbus 320/319 aircraft of the Croatia Airlines results in approximate calculation in fuel saving which amounts to 1.5 x 106 kg annually (only on Zagreb airport). In this way, the productiveness of an air carrier, which is an integral part of the traffic process along with the airports and air traffic control, is directly increased, thus fulfilling the purpose of air traffic technology research. KEY WORDS: navigational procedures, continuous descent approach, air traffic, ecolog

Influence of Airspeed Measurement Error – Implications for Dead Reckoning Navigation

Errors in navigational instruments can significantly affect flight safety. Airspeed is a key piece of navigational data that depends on accurately measured air pressure, which in turn depends on accurately measured air temperature. Instead of measuring the outside air temperature in real time, cockpit instruments are preprogramed with standard air temperature values for different flight altitudes, but atmospheric conditions can cause the actual temperature to deviate substantially from these standard values. In the present study, test flights were conducted under various atmospheric conditions to examine how the actual temperature affects the deviation of the actual airspeed from the measured airspeed. Results indicate that the differences between the actual and the standard temperature, and not those between the actual and the standard pressure, are the primary cause of deviations of the measured from the actual airspeed. The results of this study may help establish aircraft flight models based on more accurate estimates of navigational parameters