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Module 13. Aircraft aerodynamics, structures and systems

on power up, the IRS obtains position

  • latitude and longitude from previous position
  • longitude from previous position
  • latitude from previous position

Explanation

On power-up the inertial reference system can recover latitude from its last stored position because latitude is needed for the gyrocompass alignment that levels and aligns the platform. Longitude, however, must normally be entered by the crew, so only the latitude is taken from the previous position.

Gibbo280490 asking:

I have read many conflicting answers on the net and i thought i came to the decision it was LAT, any explanations?

Community Comments (2)

M
MridulDev Posts: 48 11.03.2016 / 08:36
from what i read, IRS can't calculate local longitude, and hence it is obvious that it'll take the local longitude from previous location while it'll try to acquire local latitude. Correct/ comment me if I'm wrong.
J
Jordi Posts: 198 09.04.2021 / 11:51
IRS=obtains from the longitude of the previous position

INS=obtains from the latitude of the previous position.

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