What is HREF in the control law used for auto flare?

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Height when flare is initiated

Small negative height

Height where flare should be initiated

Maximum height where flare can be initiated

Correct Answer : Small negative height

Explanation : In the control law for auto flare, HREF is a small negative height, or bias, which ensures there is still a small downwards velocity at touchdown. This avoids the long exponential ‘tail’ to reach zero velocity and enables a reasonably precise touchdown to be achieved.

Recently Updated in Avionics Questions

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.