When does an ILS localizer coupling loop become unstable?

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Aircraft range is infinity

When no aircraft is present

Aircraft range is close to zero

When too many aircraft are present

Correct Answer : Aircraft range is close to zero

Explanation : In the localizer coupling loop gain increases as range between aircraft and runway decreases. The gain reaches a point where it becomes too large and the loop becomes unstable. Thus gain scheduling with range is required.

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What is the interval for updating data in the navigation database?

1 hour

24 hours

28 days

1 month

Correct Answer : Option (C) : 28 days

Explanation : The navigation database is updated every 28 days, according to the ICAO AiRAC cycle, and is held in non-volatile memory. It is clearly essential to maintain the recency and quality of the database and the operator is responsible for the detail contents of the database which is to ARINC 424 format.

Which one of the following is not a factor for calculating speed breaches by the FMS?

CG position

Aircraft weight

Position of the aircraft

Wind and temperature models

Correct Answer : Option (C) : Position of the aircraft

Explanation : The FMS continually monitors the aircraft envelope and ensures that the speed envelope restrictions are not breached. It also computes the optimum speeds for the various phases of the flight profile. This is carried out taking into account factors such as: Aircraft weight – computed from a knowledge of the take-off weight and the fuel consumed (measured by the engine flow meters), CG position – computed from known aircraft loading and fuel consumed, Flight level and flight plan constraints, Wind and temperature models, Company route cost index.

Which one of the following is not a navigation mode used by FMS for computing position of the aircraft?

Inertial (IRS) – GPS

Inertial (IRS) – VOR/DME

Inertial (IRS) – DME/DME

GPS only

Correct Answer : Option (D) : GPS only

Explanation : Each FMS computes the aircraft position and the position accuracy. The FMS computed position is an optimum combination of the inertial position and the GPS or radio position, depending on which equipment provides the most accurate data. This results in four navigation modes: Inertial (IRS) – GPS, Inertial (IRS) – DME/DME, Inertial (IRS) – VOR/DME, Inertial (IRS) only. The only GPS is not used as the position information is within a radius where the aircraft is flying.