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Automatic Dependent Surveillance Broadcast (ADS-B)
Published in Busyairah Syd Ali, Aircraft Surveillance Systems, 2017
In the case of unavailability of GPS, Inertial Navigation Systems (INS) can be used as a backup positioning source for ADS-B. INS, also known as Inertial Reference Unit (IRU), is an independent system comprising gyros and accelerometers that provide aircraft state, position and velocity information in response to signals resulting from inertial effects on the system components. Once initialized with a known position and heading, INS continuously calculates the aircraft position and velocity. However, there is currently no requirement to provide a backup navigation source for the ADS-B system.
Inertial navigation systems
Published in Mike Tooley, David Wyatt, Aircraft Communications and Navigation Systems, 2017
The key principles of inertial navigation are based on accelerometer and gyro references together with a navigation processing function. These can be combined within a single INS and dedicated crew interface, as illustrated in Figure 17.6. Alternatively, the accelerometers and gyros are contained within an inertial reference unit (IRU); the processing function and crew interface is then integrated within the flight management computer system (FMCS). Within the FMCS, the flight management computer (FMC) combines area navigation and performance management into a single system (described in Chapter 19).
Joint repair sourcing and stocking policies for repairables using Erlang-A and Erlang-B queueing models
Published in IISE Transactions, 2019
Shimon Bitton, Izack Cohen, Morris Cohen
The research described in this article is motivated by a project conducted with an international airline to improve the management of expensive repairable parts, such as engines, power generators, navigation and communication equipment, etc. The airline conducted a program for the purchase of a new fleet of aircraft, which included large capital expenditures for supporting the fleet through the purchase of expensive repairable parts. We observed that repairable parts in the airline industry, in general, are classified into one of two categories; failures of first category parts cause an immediate grounding of the aircraft until their replacement by good parts (most prior research only considers this category). When parts from the second category fail, the aircraft can still operate for a predetermined period of time, typically 3 to 10 days, after which it is grounded if the failed part is not replaced by a good one. Parts may also be classified into the second category if engineers issue an engineering approval for an aircraft to operate for a limited period of time with a failed part, on a case-by-case basis. It is common to refer to parts in the first category as “No-Go” parts and parts in the second category are referred to as “Go” parts. The fraction of Go parts within a modern aircraft is estimated, by our partner airline, to be half of the overall number of repairable parts. This estimation was confirmed by our examination of a list of 205 repairable parts for a Boeing 737. In this list, Go parts account for 55% of the parts and 50% of the purchase cost. Examples of Go parts (purchase prices, which are tens to 500 thousand dollars per part, are not detailed, due to propriety limitations) include electrical power generators, an air data inertial reference unit inside the navigation system, navigation computers, auto pilot system parts, communication equipment, such as radios, entertainment system parts and many more parts, which are spread throughout all aircraft systems.